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Merge pull request #736 from ryanbreen/GH-730 

Website: GH-730 (deep link into options and commands where appropriate)
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Ryan Breen 2015-02-24 15:17:10 -05:00
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website/source/docs/agent/basics.html.markdown
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@ -13,7 +13,7 @@ information, registers services, runs checks, responds to queries,
and more. The agent must run on every node that is part of a Consul cluster.
Any agent may run in one of two modes: client or server. A server
node takes on the additional responsibility of being part of the [consensus quorum](#).
node takes on the additional responsibility of being part of the [consensus quorum](/docs/internals/consensus.html).
These nodes take part in Raft and provide strong consistency and availability in
the case of failure. The higher burden on the server nodes means that usually they
should be run on dedicated instances -- they are more resource intensive than a client
@ -23,11 +23,11 @@ of their own.
## Running an Agent
The agent is started with the `consul agent` command. This command blocks,
running forever or until told to quit. The agent command takes a variety
The agent is started with the [`consul agent`](/docs/commands/agent.html) command. This
command blocks, running forever or until told to quit. The agent command takes a variety
of configuration options, but most have sane defaults.
When running `consul agent`, you should see output similar to this:
When running [`consul agent`](/docs/commands/agent.html), you should see output similar to this:
```text
$ consul agent -data-dir=/tmp/consul
@ -47,39 +47,42 @@ $ consul agent -data-dir=/tmp/consul
...
```
There are several important messages that `consul agent` outputs:
There are several important messages that [`consul agent`](/docs/commands/agent.html) outputs:
* **Node name**: This is a unique name for the agent. By default, this
is the hostname of the machine, but you may customize it using the `-node` flag.
is the hostname of the machine, but you may customize it using the
[`-node`](/docs/agent/options.html#_node) flag.
* **Datacenter**: This is the datacenter in which the agent is configured to run.
Consul has first-class support for multiple datacenters; however, to work efficiently,
each node must be configured to report its datacenter. The `-dc` flag
each node must be configured to report its datacenter. The [`-dc`](/docs/agent/options.html#_dc) flag
can be used to set the datacenter. For single-DC configurations, the agent
will default to "dc1".
* **Server**: This indicates whether the agent is running in server or client mode.
Server nodes have the extra burden of participating in the consensus quorum,
storing cluster state, and handling queries. Additionally, a server may be
in "bootstrap" mode. Multiple servers cannot be in bootstrap mode as that would
put the cluster in an inconsistent state.
in ["bootstrap"](/docs/agent/options.html#_bootstrap_expect) mode. Multiple servers
cannot be in bootstrap mode as that would put the cluster in an inconsistent state.
* **Client Addr**: This is the address used for client interfaces to the agent.
This includes the ports for the HTTP, DNS, and RPC interfaces. The RPC
address is used by other `consul` commands (such as `consul members`, `consul join`,
address is used by other `consul` commands (such as
[`consul members`](/docs/commands/members.html), [`consul join`](/docs/commands/join.html),
etc) which query and control a running agent. By default, this binds only to localhost. If you
change this address or port, you'll have to specify an `-rpc-addr` whenever
you run commands such as `consul members` to indicate how to reach the
agent. Other applications can also use the RPC address and port [to control Consul](/docs/agent/rpc.html).
change this address or port, you'll have to specify a `-rpc-addr` whenever you run
commands such as [`consul members`](/docs/commands/members.html) to indicate how to
reach the agent. Other applications can also use the RPC address and port
[to control Consul](/docs/agent/rpc.html).
* **Cluster Addr**: This is the address and set of ports used for communication between
Consul agents in a cluster. Not all Consul agents in a cluster have to
use the same port, but this address **MUST** be reachable by all other nodes.
* **Atlas**: This shows the [Atlas infrastructure](https://atlas.hashicorp.com)
the node is registered with. It also indicates if auto join is enabled.
The Atlas infrastructure is set using `-atlas` and auto-join is enabled by
setting `-atlas-join`.
with which the node is registered. It also indicates if auto-join is enabled.
The Atlas infrastructure is set using [`-atlas`](/docs/agent/options.html#_atlas)
and auto-join is enabled by setting [`-atlas-join`](/docs/agent/options.html#_atlas_join).
## Stopping an Agent
@ -110,7 +113,8 @@ this lifecycle is useful for building a mental model of an agent's interactions
with a cluster and how the cluster treats a node.
When an agent is first started, it does not know about any other node in the cluster.
To discover its peers, it must _join_ the cluster. This is done with the `join`
To discover its peers, it must _join_ the cluster. This is done with the
[`join`](/docs/commands/join.html)
command or by providing the proper configuration to auto-join on start. Once a node
joins, this information is gossiped to the entire cluster, meaning all nodes will
eventually be aware of each other. If the agent is a server, existing servers will

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@ -33,48 +33,57 @@ configuration reload.
The options below are all specified on the command-line.
* <a id="advertise"></a>`-advertise` - The advertise address is used to change the address that we
advertise to other nodes in the cluster. By default, the `-bind` address is
* <a name="_advertise"></a><a href="#_advertise">`-advertise`</a> - The advertise
address is used to change the address that we
advertise to other nodes in the cluster. By default, the [`-bind`](#_bind) address is
advertised. However, in some cases, there may be a routable address that cannot
be bound. This flag enables gossiping a different address to support this.
If this address is not routable, the node will be in a constant flapping state
as other nodes will treat the non-routability as a failure.
* <a id="atlas"></a>`-atlas` - This flag enables [Atlas](https://atlas.hashicorp.com) integration.
* <a name="_atlas"></a><a href="#_atlas">`-atlas`</a> - This flag
enables [Atlas](https://atlas.hashicorp.com) integration.
It is used to provide the Atlas infrastructure name and the SCADA connection.
This enables Atlas features such as the dashboard and node auto joining.
* <a id="atlas_join"></a>`-atlas-join` - When set, enables auto-join via Atlas. Atlas will track the most
recent members to join the infrastructure named by `-atlas` and automatically
* <a name="_atlas_join"></a><a href="#_atlas_join">`-atlas-join`</a> - When set, enables auto-join
via Atlas. Atlas will track the most
recent members to join the infrastructure named by [`-atlas`](#_atlas) and automatically
join them on start. For servers, the LAN and WAN pool are both joined.
* <a id="atlas_token"></a>`-atlas-token` - Provides the Atlas API authentication token. This can also be provided
* <a name="_atlas_token"></a><a href="#_atlas_token">`-atlas-token`</a> - Provides the Atlas
API authentication token. This can also be provided
using the `ATLAS_TOKEN` environment variable. Required for use with Atlas.
* <a id="bootstrap_anchor"></a>`-bootstrap` - This flag is used to control if a server is in "bootstrap" mode. It is important that
* <a name="_bootstrap"></a><a href="#_bootstrap">`-bootstrap`</a> - This flag is used to control if a
server is in "bootstrap" mode. It is important that
no more than one server *per* datacenter be running in this mode. Technically, a server in bootstrap mode
is allowed to self-elect as the Raft leader. It is important that only a single node is in this mode;
otherwise, consistency cannot be guaranteed as multiple nodes are able to self-elect.
It is not recommended to use this flag after a cluster has been bootstrapped.
* <a id="bootstrap_expect"></a>`-bootstrap-expect` - This flag provides the number of expected servers in the datacenter.
* <a name="_bootstrap_expect"></a><a href="#_bootstrap_expect">`-bootstrap-expect`</a> - This flag
provides the number of expected servers in the datacenter.
Either this value should not be provided or the value must agree with other servers in
the cluster. When provided, Consul waits until the specified number of servers are
available and then bootstraps the cluster. This allows an initial leader to be elected
automatically. This cannot be used in conjunction with the `-bootstrap` flag.
automatically. This cannot be used in conjunction with the legacy [`-bootstrap`](#_bootstrap) flag.
* <a id="bind"></a>`-bind` - The address that should be bound to for internal cluster communications.
* <a name="_bind"></a><a href="#_bind">`-bind`</a> - The address that should be bound to
for internal cluster communications.
This is an IP address that should be reachable by all other nodes in the cluster.
By default, this is "0.0.0.0", meaning Consul will use the first available private
IP address. Consul uses both TCP and UDP and the same port for both. If you
have any firewalls, be sure to allow both protocols.
* <a id="client"></a>`-client` - The address to which Consul will bind client interfaces,
* <a name="_client"></a><a href="#_client">`-client`</a> - The address to which
Consul will bind client interfaces,
including the HTTP, DNS, and RPC servers. By default, this is "127.0.0.1",
allowing only loopback connections. The RPC address is used by other Consul
commands, such as `consul members`, in order to query a running Consul agent.
* <a id="config_file"></a>`-config-file` - A configuration file to load. For more information on
* <a name="_config_file"></a><a href="#_config_file">`-config-file`</a> - A configuration file
to load. For more information on
the format of this file, read the [Configuration Files](#configuration_files) section.
This option can be specified multiple times to load multiple configuration
files. If it is specified multiple times, configuration files loaded later
@ -82,27 +91,32 @@ The options below are all specified on the command-line.
single-value keys (string, int, bool) will simply have their values replaced
while list types will be appended together.
* <a id="config_dir"></a>`-config-dir` - A directory of configuration files to load. Consul will
* <a name="_config_dir"></a><a href="#_config_dir">`-config-dir`</a> - A directory of
configuration files to load. Consul will
load all files in this directory with the suffix ".json". The load order
is alphabetical, and the the same merge routine is used as with the
[`config-file`](#config_file) option above. For more information
[`config-file`](#_config_file) option above. For more information
on the format of the configuration files, see the [Configuration Files](#configuration_files) section.
* <a id="data_dir"></a>`-data-dir` - This flag provides a data directory for the agent to store state.
* <a name="_data_dir"></a><a href="#_data_dir">`-data-dir`</a> - This flag provides
a data directory for the agent to store state.
This is required for all agents. The directory should be durable across reboots.
This is especially critical for agents that are running in server mode as they
must be able to persist cluster state. Additionally, the directory must support
the use of filesystem locking, meaning some types of mounted folders (e.g. VirtualBox
shared folders) may not be suitable.
* <a id="dc"></a>`-dc` - This flag controls the datacenter in which the agent is running. If not provided,
* <a name="_dc"></a><a href="#_dc">`-dc`</a> - This flag controls the datacenter in
which the agent is running. If not provided,
it defaults to "dc1". Consul has first-class support for multiple datacenters, but
it relies on proper configuration. Nodes in the same datacenter should be on a single
LAN.
* <a id="encrypt"></a>`-encrypt` - Specifies the secret key to use for encryption of Consul
* <a name="_encrypt"></a><a href="#_encrypt">`-encrypt`</a> - Specifies the secret key to
use for encryption of Consul
network traffic. This key must be 16-bytes that are Base64-encoded. The
easiest way to create an encryption key is to use `consul keygen`. All
easiest way to create an encryption key is to use
[`consul keygen`](/docs/commands/keygen.html). All
nodes within a cluster must share the same encryption key to communicate.
The provided key is automatically persisted to the data directory and loaded
automatically whenever the agent is restarted. This means that to encrypt
@ -111,60 +125,72 @@ The options below are all specified on the command-line.
initialized with an encryption key, then the provided key is ignored and
a warning will be displayed.
* <a id="join"></a>`-join` - Address of another agent to join upon starting up. This can be
* <a name="_join"></a><a href="#_join">`-join`</a> - Address of another agent
to join upon starting up. This can be
specified multiple times to specify multiple agents to join. If Consul is
unable to join with any of the specified addresses, agent startup will
fail. By default, the agent won't join any nodes when it starts up.
* <a id="retry_join"></a>`-retry-join` - Similar to [`-join`](#join) but allows retrying a join if the first
* <a name="_retry_join"></a><a href="#_retry_join">`-retry-join`</a> - Similar
to [`-join`](#_join) but allows retrying a join if the first
attempt fails. This is useful for cases where we know the address will become
available eventually.
* <a id="retry_interval"></a>`-retry-interval` - Time to wait between join attempts. Defaults to 30s.
* <a name="_retry_interval"></a><a href="#_retry_interval">`-retry-interval`</a> - Time
to wait between join attempts. Defaults to 30s.
* <a id="retry_max"></a>`-retry-max` - The maximum number of [`-join`](#join) attempts to be made before exiting
* <a name="_retry_max"></a><a href="#_retry_max">`-retry-max`</a> - The maximum number
of [`-join`](#_join) attempts to be made before exiting
with return code 1. By default, this is set to 0 which is interpreted as infinite
retries.
* <a id="join_wan"></a>`-join-wan` - Address of another wan agent to join upon starting up. This can be
* <a name="_join_wan"></a><a href="#_join_wan">`-join-wan`</a> - Address of another
wan agent to join upon starting up. This can be
specified multiple times to specify multiple WAN agents to join. If Consul is
unable to join with any of the specified addresses, agent startup will
fail. By default, the agent won't [`-join-wan`](#join_wan) any nodes when it starts up.
fail. By default, the agent won't [`-join-wan`](#_join_wan) any nodes when it starts up.
* <a id="retry_join_wan"></a>`-retry-join-wan` - Similar to [`retry-join`](#retry_join) but allows retrying
a wan join if the first attempt fails. This is useful for cases where we know the address will become
* <a name="_retry_join_wan"></a><a href="#_retry_join_wan">`-retry-join-wan`</a> - Similar
to [`retry-join`](#_retry_join) but allows retrying a wan join if the first attempt fails.
This is useful for cases where we know the address will become
available eventually.
* <a id="retry_interval_wan"></a>`-retry-interval-wan` - Time to wait between [`-join-wan`](#join_wan) attempts.
* <a name="_retry_interval_wan"></a><a href="#_retry_interval_wan">`-retry-interval-wan`</a> - Time
to wait between [`-join-wan`](#_join_wan) attempts.
Defaults to 30s.
* <a id="retry_max_wan"></a>`-retry-max-wan` - The maximum number of [`-join-wan`](#join_wan) attempts to
be made before exiting with return code 1. By default, this is set to 0 which is interpreted as infinite
retries.
* <a name="_retry_max_wan"></a><a href="#_retry_max_wan">`-retry-max-wan`</a> - The maximum
number of [`-join-wan`](#_join_wan) attempts to be made before exiting with return code 1.
By default, this is set to 0 which is interpreted as infinite retries.
* <a id="log_level"></a>`-log-level` - The level of logging to show after the Consul agent has
started. This defaults to "info". The available log levels are "trace",
"debug", "info", "warn", and "err". Note that you can always connect to an
agent via `consul monitor` and use any log level. Also, the log level can
be changed during a config reload.
* <a name="_log_level"></a><a href="#_log_level">`-log-level`</a> - The level of logging to
show after the Consul agent has started. This defaults to "info". The available log levels are
"trace", "debug", "info", "warn", and "err". Note that you can always connect to an
agent via [`consul monitor`](/docs/commands/monitor.html) and use any log level. Also, the
log level can be changed during a config reload.
* <a id="node"></a>`-node` - The name of this node in the cluster. This must be unique within
the cluster. By default this is the hostname of the machine.
* <a name="_node"></a><a href="#_node">`-node`</a> - The name of this node in the cluster.
This must be unique within the cluster. By default this is the hostname of the machine.
* <a id="protocol"></a>`-protocol` - The Consul protocol version to use. This defaults to the latest
version. This should be set only when [upgrading](/docs/upgrading.html).
* <a name="_pid_file"></a><a href="#_pid_file">`-pid-file`</a> - This flag provides the file
path for the agent to store its PID. This is useful for sending signals (for example, `SIGINT`
to close the agent or `SIGHUP` to update check definit
* <a name="_protocol"></a><a href="#_protocol">`-protocol`</a> - The Consul protocol version to
use. This defaults to the latest version. This should be set only when [upgrading](/docs/upgrading.html).
You can view the protocol versions supported by Consul by running `consul -v`.
* <a id="recursor"></a>`-recursor` - Specifies the address of an upstream DNS
* <a name="_recursor"></a><a href="#_recursor">`-recursor`</a> - Specifies the address of an upstream DNS
server. This option may be provided multiple times, and is functionally
equivalent to the [`recursors` configuration option](#recursors).
* <a id="rejoin"></a>`-rejoin` - When provided, Consul will ignore a previous leave and attempt to
rejoin the cluster when starting. By default, Consul treats leave as a permanent
intent and does not attempt to join the cluster again when starting. This flag
* <a name="_rejoin"></a><a href="#_rejoin">`-rejoin`</a> - When provided, Consul will ignore a
previous leave and attempt to rejoin the cluster when starting. By default, Consul treats leave
as a permanent intent and does not attempt to join the cluster again when starting. This flag
allows the previous state to be used to rejoin the cluster.
* <a id="server"></a>`-server` - This flag is used to control if an agent is in server or client mode. When provided,
* <a name="_server"></a><a href="#_server">`-server`</a> - This flag is used to control if an
agent is in server or client mode. When provided,
an agent will act as a Consul server. Each Consul cluster must have at least one server and ideally
no more than 5 per datacenter. All servers participate in the Raft consensus algorithm to ensure that
transactions occur in a consistent, linearizable manner. Transactions modify cluster state, which
@ -172,16 +198,14 @@ The options below are all specified on the command-line.
participate in a WAN gossip pool with server nodes in other datacenters. Servers act as gateways
to other datacenters and forward traffic as appropriate.
* <a id="syslog"></a>`-syslog` - This flag enables logging to syslog. This is only supported on Linux
and OSX. It will result in an error if provided on Windows.
* <a name="_syslog"></a><a href="#_syslog">`-syslog`</a> - This flag enables logging to syslog. This
is only supported on Linux and OSX. It will result in an error if provided on Windows.
* <a id="ui_dir"></a>`-ui-dir` - This flag provides the directory containing the Web UI resources
for Consul. This must be provided to enable the Web UI. The directory must be readable.
* <a name="_ui_dir"></a><a href="#_ui_dir">`-ui-dir`</a> - This flag provides the directory containing
the Web UI resources for Consul. This must be provided to enable the Web UI. The directory must be
readable.ions) to the agent.
* <a id="pid_file"></a>`-pid-file` - This flag provides the file path for the agent to store its PID. This is useful for
sending signals (for example, `SIGINT` to close the agent or `SIGHUP` to update check definitions) to the agent.
## <a id="configuration_files"></a>Configuration Files
## <a name="configuration_files"></a>Configuration Files
In addition to the command-line options, configuration can be put into
files. This may be easier in certain situations, for example when Consul is
@ -218,42 +242,44 @@ definitions support being updated during a reload.
#### Configuration Key Reference
* <a id="acl_datacenter"></a>`acl_datacenter` - Only used by servers. This designates the datacenter which
is authoritative for ACL information. It must be provided to enable ACLs.
All servers and datacenters must agree on the ACL datacenter. Setting it on
the servers is all you need for enforcement, but for the APIs to forward properly
from the clients, it must be set on them too. Future changes may move
enforcement to the edges, so it's best to just set `acl_datacenter` on all nodes.
* <a name="acl_datacenter"></a><a href="#acl_datacenter">`acl_datacenter`</a> - Only
used by servers. This designates the datacenter which
is authoritative for ACL information. It must be provided to enable ACLs.
All servers and datacenters must agree on the ACL datacenter. Setting it on
the servers is all you need for enforcement, but for the APIs to forward properly
from the clients, it must be set on them too. Future changes may move
enforcement to the edges, so it's best to just set `acl_datacenter` on all nodes.
* `acl_default_policy` - Either "allow" or "deny"; defaults to "allow". The
default policy controls the behavior of a token when there is no matching
rule. In "allow" mode, ACLs are a blacklist: any operation not specifically
* <a name="acl_default_policy"></a><a href="#acl_default_policy">`acl_default_policy`</a> - Either
"allow" or "deny"; defaults to "allow". The default policy controls the behavior of a token when
there is no matching rule. In "allow" mode, ACLs are a blacklist: any operation not specifically
prohibited is allowed. In "deny" mode, ACLs are a whitelist: any operation not
specifically allowed is blocked.
* `acl_down_policy` - Either "allow", "deny" or "extend-cache"; "extend-cache" is the
default. In the case that the policy for a token cannot be read from the
[`acl_datacenter`](#acl_datacenter) or leader node, the down policy is applied. In "allow" mode,
all actions are permitted, "deny" restricts all operations, and "extend-cache"
allows any cached ACLs to be used, ignoring their TTL values. If a non-cached
ACL is used, "extend-cache" acts like "deny".
* <a name="acl_down_policy"></a><a href="#acl_down_policy">`acl_down_policy`</a> - Either
"allow", "deny" or "extend-cache"; "extend-cache" is the default. In the case that the
policy for a token cannot be read from the [`acl_datacenter`](#acl_datacenter) or leader
node, the down policy is applied. In "allow" mode, all actions are permitted, "deny" restricts
all operations, and "extend-cache" allows any cached ACLs to be used, ignoring their TTL
values. If a non-cached ACL is used, "extend-cache" acts like "deny".
* `acl_master_token` - Only used for servers in the [`acl_datacenter`](#acl_datacenter). This token
will be created with management-level permissions if it does not exist. It allows
operators to bootstrap the ACL system with a token ID that is well-known.
* <a name="acl_master_token"></a><a href="#acl_master_token">`acl_master_token`</a> - Only used
for servers in the [`acl_datacenter`](#acl_datacenter). This token will be created with management-level
permissions if it does not exist. It allows operators to bootstrap the ACL system
with a token ID that is well-known.
* `acl_token` - When provided, the agent will use this token when making requests
to the Consul servers. Clients can override this token on a per-request basis
by providing the "?token" query parameter. When not provided, the empty token, which
maps to the 'anonymous' ACL policy, is used.
* <a name="acl_token"></a><a href="#acl_token">`acl_token`</a> - When provided, the agent will use this
token when making requests to the Consul servers. Clients can override this token on a per-request
basis by providing the "?token" query parameter. When not provided, the empty token, which maps to
the 'anonymous' ACL policy, is used.
* `acl_ttl` - Used to control Time-To-Live caching of ACLs. By default, this
is 30 seconds. This setting has a major performance impact: reducing it will
cause more frequent refreshes while increasing it reduces the number of caches.
However, because the caches are not actively invalidated, ACL policy may be stale
up to the TTL value.
* <a name="acl_ttl"></a><a href="#acl_ttl">`acl_ttl`</a> - Used to control Time-To-Live caching of ACLs.
By default, this is 30 seconds. This setting has a major performance impact: reducing it will cause
more frequent refreshes while increasing it reduces the number of caches. However, because the caches
are not actively invalidated, ACL policy may be stale up to the TTL value.
* `addresses` - This is a nested object that allows setting bind addresses.
* <a name="addresses"></a><a href="#addresses">`addresses`</a> - This is a nested object that allows
setting bind addresses.
<br><br>
Both `rpc` and `http` support binding to Unix domain sockets. A socket can be
specified in the form `unix:///path/to/socket`. A new domain socket will be
@ -273,34 +299,43 @@ definitions support being updated during a reload.
* `http` - The HTTP API. Defaults to `client_addr`
* `rpc` - The RPC endpoint. Defaults to `client_addr`
* `advertise_addr` - Equivalent to the [`-advertise` command-line flag](#advertise).
* <a name="advertise_addr"></a><a href="#advertise_addr">`advertise_addr`</a> Equivalent to
the [`-advertise` command-line flag](#_advertise).
* `atlas_acl_token` - When provided, any requests made by Atlas will use this ACL
token unless explicitly overriden. When not provided the `acl_token` is used.
This can be set to 'anonymous' to reduce permission below that of `acl_token`.
* <a name="atlas_acl_token"></a><a href="#atlas_acl_token">`atlas_acl_token`</a> When provided,
any requests made by Atlas will use this ACL token unless explicitly overriden. When not provided
the [`acl_token`](#acl_token) is used. This can be set to 'anonymous' to reduce permission below
that of [`acl_token`](#acl_token).
* `atlas_infrastructure` - Equivalent to the [`-atlas` command-line flag](#atlas).
* <a name="atlas_infrastructure"></a><a href="#atlas_infrastructure">`atlas_infrastructure`</a>
Equivalent to the [`-atlas` command-line flag](#_atlas).
* `atlas_join` - Equivalent to the [`-atlas-join` command-line flag](#atlas_join).
* <a name="atlas_join"></a><a href="#atlas_join">`atlas_join`</a> Equivalent to the
[`-atlas-join` command-line flag](#_atlas_join).
* `atlas_token` - Equivalent to the [`-atlas-token` command-line flag](#atlas_token).
* <a name="atlas_token"></a><a href="#atlas_token">`atlas_token`</a> Equivalent to the
[`-atlas-token` command-line flag](#_atlas_token).
* `bootstrap` - Equivalent to the [`-bootstrap` command-line flag](#bootstrap_anchor).
* <a name="bootstrap"></a><a href="#bootstrap">`bootstrap`</a> Equivalent to the
[`-bootstrap` command-line flag](#_bootstrap).
* `bootstrap_expect` - Equivalent to the [`-bootstrap-expect` command-line flag](#bootstrap_expect).
* <a name="bootstrap_expect"></a><a href="#bootstrap_expect">`bootstrap_expect`</a> Equivalent
to the [`-bootstrap-expect` command-line flag](#_bootstrap_expect).
* `bind_addr` - Equivalent to the [`-bind` command-line flag](#bind).
* <a name="bind_addr"></a><a href="#bind_addr">`bind_addr`</a> Equivalent to the
[`-bind` command-line flag](#_bind).
* <a id="ca_file"></a>`ca_file` - This provides a file path to a PEM-encoded certificate authority.
The certificate authority is used to check the authenticity of client and server
connections with the appropriate [`verify_incoming`](#verify_incoming) or
* <a name="ca_file"></a><a href="#ca_file">`ca_file`</a> This provides a file path to a PEM-encoded
certificate authority. The certificate authority is used to check the authenticity of client and
server connections with the appropriate [`verify_incoming`](#verify_incoming) or
[`verify_outgoing`](#verify_outgoing) flags.
* <a id="cert_file"></a>`cert_file` - This provides a file path to a PEM-encoded certificate.
The certificate is provided to clients or servers to verify the agent's authenticity.
It must be provided along with [`key_file`](#key_file).
* <a name="cert_file"></a><a href="#cert_file">`cert_file`</a> This provides a file path to a
PEM-encoded certificate. The certificate is provided to clients or servers to verify the agent's
authenticity. It must be provided along with [`key_file`](#key_file).
* `check_update_interval` - This interval controls how often check output from
* <a name="check_update_interval"></a><a href="#check_update_interval">`check_update_interval`</a>
This interval controls how often check output from
checks in a steady state is synchronized with the server. By default, this is
set to 5 minutes ("5m"). Many checks which are in a steady state produce
slightly different output per run (timestamps, etc) which cause constant writes.
@ -308,71 +343,81 @@ definitions support being updated during a reload.
reduce write pressure. If a check ever changes state, the new state and associated
output is synchronized immediately. To disable this behavior, set the value to "0s".
* `client_addr` - Equivalent to the [`-client` command-line flag](#client).
* <a name="client_addr"></a><a href="#client_addr">`client_addr`</a> Equivalent to the
[`-client` command-line flag](#_client).
* `datacenter` - Equivalent to the [`-dc` command-line flag](#dc).
* <a name="datacenter"></a><a href="#datacenter">`datacenter`</a> Equivalent to the
[`-dc` command-line flag](#_dc).
* `data_dir` - Equivalent to the [`-data-dir` command-line flag](#data_dir).
* <a name="data_dir"></a><a href="#data_dir">`data_dir`</a> Equivalent to the
[`-data-dir` command-line flag](#_data_dir).
* `disable_anonymous_signature` - Disables providing an anonymous signature for
de-duplication with the update check. See [`disable_update_check`](#disable_update_check).
* <a name="disable_anonymous_signature"></a><a href="#disable_anonymous_signature">
`disable_anonymous_signature`</a> Disables providing an anonymous signature for de-duplication
with the update check. See [`disable_update_check`](#disable_update_check).
* `disable_remote_exec` - Disables support for remote execution. When set to true,
the agent will ignore any incoming remote exec requests.
* <a name="disable_remote_exec"></a><a href="#disable_remote_exec">`disable_remote_exec`</a>
Disables support for remote execution. When set to true, the agent will ignore any incoming
remote exec requests.
* <a id="disable_update_check"></a>`disable_update_check` - Disables automatic checking for security bulletins and
new version releases.
* <a name="disable_update_check"></a><a href="#disable_update_check">`disable_update_check`</a>
Disables automatic checking for security bulletins and new version releases.
* `dns_config` - This object allows a number of sub-keys to be set which can tune
how DNS queries are serviced. See this guide on [DNS caching](/docs/guides/dns-cache.html)
for more detail.
* <a name="dns_config"></a><a href="#dns_config">`dns_config`</a> This object allows a number
of sub-keys to be set which can tune how DNS queries are serviced. See this guide on
[DNS caching](/docs/guides/dns-cache.html) for more detail.
<br><br>
The following sub-keys are available:
* `allow_stale` - Enables a stale query for DNS information. This allows any Consul
server, rather than only the leader, to service the request. The advantage of this is
you get linear read scalability with Consul servers. By default, this is false, meaning
all requests are serviced by the leader, providing stronger consistency but
less throughput and higher latency.
* <a name="allow_stale"></a><a href="#allow_stale">`allow_stale`</a> - Enables a stale query
for DNS information. This allows any Consul server, rather than only the leader, to service
the request. The advantage of this is you get linear read scalability with Consul servers.
By default, this is false, meaning all requests are serviced by the leader, providing stronger
consistency but less throughput and higher latency.
* `max_stale` - When `allow_stale` is specified, this is used to limit how
* <a name="max_stale"></a><a href="#max_stale">`max_stale`</a> When [`allow_stale`](#allow_stale)
is specified, this is used to limit how
stale results are allowed to be. By default, this is set to "5s":
if a Consul server is more than 5 seconds behind the leader, the query will be
re-evaluated on the leader to get more up-to-date results.
* `node_ttl` - By default, this is "0s", so all node lookups are served with
a 0 TTL value. DNS caching for node lookups can be enabled by setting this value. This
should be specified with the "s" suffix for second or "m" for minute.
* <a name="node_ttl"></a><a href="#node_ttl">`node_ttl`</a> By default, this is "0s", so all
node lookups are served with a 0 TTL value. DNS caching for node lookups can be enabled by
setting this value. This should be specified with the "s" suffix for second or "m" for minute.
* `service_ttl` - This is a sub-object which allows for setting a TTL on service lookups
with a per-service policy. The "*" wildcard service can be used when
there is no specific policy available for a service. By default, all services are served
with a 0 TTL value. DNS caching for service lookups can be enabled by setting this value.
* <a name="service_ttl"></a><a href="#service_ttl">`service_ttl`</a> This is a sub-object
which allows for setting a TTL on service lookups with a per-service policy. The "*" wildcard
service can be used when there is no specific policy available for a service. By default, all
services are served with a 0 TTL value. DNS caching for service lookups can be enabled by
setting this value.
* `enable_truncate` - If set to true, a UDP DNS query that would return more than 3 records
will set the truncated flag, indicating to clients that they should re-query using TCP to
get the full set of records.
* <a name="enable_truncate"></a><a href="#enable_truncate">`enable_truncate`</a> If set to
true, a UDP DNS query that would return more than 3 records will set the truncated flag,
indicating to clients that they should re-query using TCP to get the full set of records.
* `only_passing` - If set to true, any nodes whose healthchecks are not passing will be
excluded from DNS results. By default (or if set to false), only nodes whose healthchecks
are failing as critical will be excluded.
* <a name="only_passing"></a><a href="#only_passing">`only_passing`</a> If set to true, any
nodes whose healthchecks are not passing will be excluded from DNS results. By default (or
if set to false), only nodes whose healthchecks are failing as critical will be excluded.
* `domain` - By default, Consul responds to DNS queries in the "consul." domain.
This flag can be used to change that domain. All queries in this domain are assumed
to be handled by Consul and will not be recursively resolved.
* <a name="domain"></a><a href="#domain">`domain`</a> By default, Consul responds to DNS queries
in the "consul." domain. This flag can be used to change that domain. All queries in this domain
are assumed to be handled by Consul and will not be recursively resolved.
* `enable_debug` - When set, enables some additional debugging features. Currently,
this is only used to set the runtime profiling HTTP endpoints.
* <a name="enable_debug"></a><a href="#enable_debug">`enable_debug`</a> When set, enables some
additional debugging features. Currently, this is only used to set the runtime profiling HTTP endpoints.
* <a id="enable_syslog"></a>`enable_syslog` - Equivalent to the [`-syslog` command-line flag](#syslog).
* <a name="enable_syslog"></a><a href="#enable_syslog">`enable_syslog`</a> Equivalent to
the [`-syslog` command-line flag](#_syslog).
* `encrypt` - Equivalent to the [`-encrypt` command-line flag](#encrypt).
* <a name="encrypt"></a><a href="#encrypt">`encrypt`</a> Equivalent to the
[`-encrypt` command-line flag](#_encrypt).
* <a id="key_file"></a>`key_file` - This provides a the file path to a PEM-encoded private key.
The key is used with the certificate to verify the agent's authenticity.
* <a name="key_file"></a><a href="#key_file">`key_file`</a> This provides a the file path to a
PEM-encoded private key. The key is used with the certificate to verify the agent's authenticity.
This must be provided along with [`cert_file`](#cert_file).
* `http_api_response_headers` - This object allows adding headers to the HTTP API
* <a name="http_api_response_headers"></a><a href="#http_api_response_headers">`http_api_response_headers`</a>
This object allows adding headers to the HTTP API
responses. For example, the following config can be used to enable
[CORS](http://en.wikipedia.org/wiki/Cross-origin_resource_sharing) on
the HTTP API endpoints:
@ -385,81 +430,96 @@ definitions support being updated during a reload.
}
```
* <a id="leave_on_terminate"></a>`leave_on_terminate` - If enabled, when the agent receives a TERM signal,
* <a name="leave_on_terminate"></a><a href="#leave_on_terminate">`leave_on_terminate`</a> If
enabled, when the agent receives a TERM signal,
it will send a `Leave` message to the rest of the cluster and gracefully
leave. Defaults to false.
* `log_level` - Equivalent to the [`-log-level` command-line flag](#log_level).
* <a name="log_level"></a><a href="#log_level">`log_level`</a> Equivalent to the
[`-log-level` command-line flag](#_log_level).
* `node_name` - Equivalent to the [`-node` command-line flag](#node).
* <a name="node_name"></a><a href="#node_name">`node_name`</a> Equivalent to the
[`-node` command-line flag](#_node).
* `ports` - This is a nested object that allows setting the bind ports
for the following keys:
* `dns` - The DNS server, -1 to disable. Default 8600.
* `http` - The HTTP API, -1 to disable. Default 8500.
* `https` - The HTTPS API, -1 to disable. Default -1 (disabled).
* `rpc` - The RPC endpoint. Default 8400.
* `serf_lan` - The Serf LAN port. Default 8301.
* `serf_wan` - The Serf WAN port. Default 8302.
* `server` - Server RPC address. Default 8300.
* <a name="ports"></a><a href="#ports">`ports`</a> This is a nested object that allows setting
the bind ports for the following keys:
* <a name="dns_port"></a><a href="#dns_port">`dns`</a> - The DNS server, -1 to disable. Default 8600.
* <a name="http_port"></a><a href="#http_port">`http`</a> - The HTTP API, -1 to disable. Default 8500.
* <a name="https_port"></a><a href="#https_port">`https`</a> - The HTTPS API, -1 to disable. Default -1 (disabled).
* <a name="rpc_port"></a><a href="#rpc_port">`rpc`</a> - The RPC endpoint. Default 8400.
* <a name="serf_lan_port"></a><a href="#serf_lan_port">`serf_lan`</a> - The Serf LAN port. Default 8301.
* <a name="serf_wan_port"></a><a href="#serf_wan_port">`serf_wan`</a> - The Serf WAN port. Default 8302.
* <a name="server_rpc_port"></a><a href="#server_rpc_port">`server`</a> - Server RPC address. Default 8300.
* `protocol` - Equivalent to the [`-protocol` command-line flag](#protocol).
* <a name="protocol"></a><a href="#protocol">`protocol`</a> Equivalent to the
[`-protocol` command-line flag](#_protocol).
* `recursor` - Provides a single recursor address. This has been deprecated, and
the value is appended to the [`recursors`](#recursors) list for backwards compatibility.
* <a name="recursor"></a><a href="#recursor">`recursor`</a> Provides a single recursor address.
This has been deprecated, and the value is appended to the [`recursors`](#recursors) list for
backwards compatibility.
* <a id="recursors"></a>`recursors` - This flag provides addresses of upstream DNS servers that are used to
recursively resolve queries if they are not inside the service domain for consul. For example,
a node can use Consul directly as a DNS server, and if the record is outside of the "consul." domain,
the query will be resolved upstream.
* <a name="recursors"></a><a href="#recursors">`recursors`</a> This flag provides addresses of
upstream DNS servers that are used to recursively resolve queries if they are not inside the service
domain for consul. For example, a node can use Consul directly as a DNS server, and if the record is
outside of the "consul." domain, the query will be resolved upstream.
* `rejoin_after_leave` - Equivalent to the [`-rejoin` command-line flag](#rejoin).
* <a name="rejoin_after_leave"></a><a href="#rejoin_after_leave">`rejoin_after_leave`</a> Equivalent
to the [`-rejoin` command-line flag](#_rejoin).
* `retry_join` - Equivalent to the [`-retry-join` command-line flag](#retry_join). Takes a list
of addresses to attempt joining every `retry_interval` until at least one
[`-join`](#join) works.
* <a name="retry_join"></a><a href="#retry_join">`retry_join`</a> Equivalent to the
[`-retry-join` command-line flag](#_retry_join). Takes a list
of addresses to attempt joining every [`retry_interval`](#_retry_interval) until at least one
[`-join`](#_join) works.
* `retry_interval` - Equivalent to the [`-retry-interval` command-line flag](#retry_interval).
* <a name="retry_interval"></a><a href="#retry_interval">`retry_interval`</a> Equivalent to the
[`-retry-interval` command-line flag](#_retry_interval).
* `retry_join_wan` - Equivalent to the [`-retry-join-wan` command-line flag](#retry_join_wan). Takes a list
of addresses to attempt joining to WAN every [`retry_interval_wan`](#retry_interval_wan) until at least one
[`-join-wan`](#join_wan) works.
* <a name="retry_join_wan"></a><a href="#retry_join_wan">`retry_join_wan`</a> Equivalent to the
[`-retry-join-wan` command-line flag](#_retry_join_wan). Takes a list
of addresses to attempt joining to WAN every [`retry_interval_wan`](#_retry_interval_wan) until at least one
[`-join-wan`](#_join_wan) works.
* `retry_interval_wan` - Equivalent to the [`-retry-interval-wan` command-line flag](#retry_interval_wan).
* <a name="retry_interval_wan"></a><a href="#retry_interval_wan">`retry_interval_wan`</a> Equivalent to the
[`-retry-interval-wan` command-line flag](#_retry_interval_wan).
* `server` - Equivalent to the [`-server` command-line flag](#server).
* <a name="server"></a><a href="#server">`server`</a> Equivalent to the
[`-server` command-line flag](#_server).
* `server_name` - When provided, this overrides the [`node_name`](#node) for the TLS certificate.
It can be used to ensure that the certificate name matches the hostname we
declare.
* <a name="server_name"></a><a href="#server_name">`server_name`</a> When provided, this overrides
the [`node_name`](#_node) for the TLS certificate. It can be used to ensure that the certificate
name matches the hostname we declare.
* `skip_leave_on_interrupt` - This is similar to [`leave_on_terminate`](#leave_on_terminate) but
* <a name="skip_leave_on_interrupt"></a><a href="#skip_leave_on_interrupt">`skip_leave_on_interrupt`</a>
This is similar to [`leave_on_terminate`](#leave_on_terminate) but
only affects interrupt handling. By default, an interrupt (such as hitting
Control-C in a shell) causes Consul to gracefully leave. Setting this to true
disables that. Defaults to false.
* `start_join` - An array of strings specifying addresses of nodes to
[`-join`](#join) upon startup.
* <a name="start_join"></a><a href="#start_join">`start_join`</a> An array of strings specifying addresses
of nodes to [`-join`](#_join) upon startup.
* `start_join_wan` - An array of strings specifying addresses of WAN nodes to
[`-join-wan`](#join_wan) upon startup.
* <a name="start_join_wan"></a><a href="#start_join_wan">`start_join_wan`</a> An array of strings specifying
addresses of WAN nodes to [`-join-wan`](#_join_wan) upon startup.
* `statsd_addr` - This provides the address of a statsd instance. If provided,
Consul will send various telemetry information to that instance for aggregation.
This can be used to capture runtime information. This sends UDP packets
only and can be used with statsd or statsite.
* <a name="statsd_addr"></a><a href="#statsd_addr">`statsd_addr`</a> This provides the address of a statsd
instance. If provided, Consul will send various telemetry information to that instance for aggregation.
This can be used to capture runtime information. This sends UDP packets only and can be used with statsd
or statsite.
* `statsite_addr` - This provides the address of a statsite instance. If provided,
Consul will stream various telemetry information to that instance for aggregation.
This can be used to capture runtime information. This streams via
* <a name="statsite_addr"></a><a href="#statsite_addr">`statsite_addr`</a> This provides the address of a
statsite instance. If provided, Consul will stream various telemetry information to that instance for
aggregation. This can be used to capture runtime information. This streams via
TCP and can only be used with statsite.
* `syslog_facility` - When [`enable_syslog`](#enable_syslog) is provided, this controls to which
* <a name="syslog_facility"></a><a href="#syslog_facility">`syslog_facility`</a> When
[`enable_syslog`](#enable_syslog) is provided, this controls to which
facility messages are sent. By default, `LOCAL0` will be used.
* `ui_dir` - Equivalent to the [`-ui-dir`](#ui_dir) command-line flag.
* <a name="ui_dir"></a><a href="#ui_dir">`ui_dir`</a> - Equivalent to the
[`-ui-dir`](#_ui_dir) command-line flag.
* <a id="unix_sockets"></a>`unix_sockets` - This allows tuning the ownership and permissions of the
* <a name="unix_sockets"></a><a href="#unix_sockets">`unix_sockets`</a> - This
allows tuning the ownership and permissions of the
Unix domain socket files created by Consul. Domain sockets are only used if
the HTTP or RPC addresses are configured with the `unix://` prefix. The
following options are valid within this construct and apply globally to all
@ -476,20 +536,23 @@ definitions support being updated during a reload.
important to test this feature on your specific distribution. This feature is
currently not functional on Windows hosts.
* <a id="verify_incoming"></a>`verify_incoming` - If set to true, Consul requires that all incoming
* <a name="verify_incoming"></a><a href="#verify_incoming">`verify_incoming`</a> - If
set to true, Consul requires that all incoming
connections make use of TLS and that the client provides a certificate signed
by the Certificate Authority from the [`ca_file`](#ca_file). By default, this is false, and
Consul will not enforce the use of TLS or verify a client's authenticity. This
only applies to Consul servers since a client never has an incoming connection.
* <a id="verify_outgoing"></a>`verify_outgoing` - If set to true, Consul requires that all outgoing connections
* <a name="verify_outgoing"></a><a href="#verify_outgoing">`verify_outgoing`</a> - If set to
true, Consul requires that all outgoing connections
make use of TLS and that the server provides a certificate that is signed by
the Certificate Authority from the [`ca_file`](#ca_file). By default, this is false, and Consul
will not make use of TLS for outgoing connections. This applies to clients and servers
as both will make outgoing connections.
* `watches` - Watches is a list of watch specifications which allow an external process
to be automatically invoked when a particular data view is updated. See the
* <a name="watches"></a><a href="#watches">`watches`</a> - Watches is a list of watch
specifications which allow an external process to be automatically invoked when a
particular data view is updated. See the
[watch documentation](/docs/agent/watches.html) for more detail. Watches can be
modified when the configuration is reloaded.

16
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View File

@ -16,11 +16,12 @@ Before a Consul cluster can begin to service requests, a server node must be ele
Thus, the first nodes that are started are generally the server nodes. Bootstrapping is the process
of joining these server nodes into a cluster.
The recommended way to bootstrap is to use the `-bootstrap-expect` [configuration
option](/docs/agent/options.html). This option informs Consul of the expected number of
The recommended way to bootstrap is to use the [`-bootstrap-expect`](/docs/agent/options.html#_bootstrap_expect)
configuration option. This option informs Consul of the expected number of
server nodes and automatically bootstraps when that many servers are available. To prevent
inconsistencies and split-brain situations (that is, clusters where multiple servers consider
themselves leader), all servers should either specify the same value for `-bootstrap-expect`
themselves leader), all servers should either specify the same value for
[`-bootstrap-expect`](/docs/agent/options.html#_bootstrap_expect)
or specify no value at all. Only servers that specify a value will attempt to bootstrap the cluster.
We recommend 3 or 5 total servers per datacenter. A single server deployment is _**highly**_ discouraged
@ -57,9 +58,9 @@ Once the join is successful, one of the nodes will output something like:
[INFO] consul: cluster leadership acquired
```
As a sanity check, the `consul info` command is a useful tool. It can be used to
As a sanity check, the [`consul info`](/docs/commands/info.html) command is a useful tool. It can be used to
verify `raft.num_peers` is now 2, and you can view the latest log index under `raft.last_log_index`.
When running `consul info` on the followers, you should see `raft.last_log_index`
When running [`consul info`](/docs/commands/info.html) on the followers, you should see `raft.last_log_index`
converge to the same value once the leader begins replication. That value represents the last
log entry that has been stored on disk.
@ -74,7 +75,8 @@ operations will fail until the servers are available.
## Manual Bootstrapping
In versions of Consul prior to 0.4, bootstrapping was a more manual process. For details on
using the `-bootstrap` flag directly, see the [manual bootstrapping guide](/docs/guides/manual-bootstrap.html).
using the [`-bootstrap`](/docs/agent/options.html#_bootstrap) flag directly, see the
[manual bootstrapping guide](/docs/guides/manual-bootstrap.html).
Manual bootstrapping is not recommended as it is more error-prone than automatic bootstrapping
with `-bootstrap-expect`.
with [`-bootstrap-expect`](/docs/agent/options.html#_bootstrap_expect).