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website: Working on getting started guide

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website/source/intro/getting-started/agent.html.markdown
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@ -4,79 +4,125 @@ page_title: "Run the Agent"
sidebar_current: "gettingstarted-agent"
---
# Run the Serf Agent
# Run the Consul Agent
After Serf is installed, the agent must be run. The agent is a lightweight
process that runs until told to quit and maintains cluster membership
and communication. The agent must be run for every node that will be part of
the cluster.
It is possible to run multiple agents, and thus participate in multiple Serf
clusters. For example, you may want to run a separate Serf cluster to
maintain web server membership info for a load balancer from another Serf
cluster that manages membership of Memcached nodes, but perhaps the web
servers need to be part of the Memcached cluster too so they can be notified
when Memcached nodes come online or go offline. Other examples include a Serf
cluster within a datacenter, and a seperate cluster used for cross WAN gossip
which has more relaxed timing.
After Consul is installed, the agent must be run. The agent can either run
in a server or client mode. Each datacenter must at least one server, and
a recommended 3 or 5. [This guide](/docs/guides/bootstrapping.html) covers
bootstrapping a new datacenter. All other agents run in client mode, which
is a very lightweight process that registers services, runs health checks,
and forwards queries to servers. The agent must be run for every node that
will be part of the cluster.
## Starting the Agent
For simplicity, we'll run a single Serf agent right now:
For simplicity, we'll run a single Consul agent in server mode right now:
```
$ serf agent
==> Starting Serf agent...
==> Serf agent running!
Node name: 'foobar'
Bind addr: '0.0.0.0:7946'
RPC addr: '127.0.0.1:7373'
$ ./bin/consul agent -server -bootstrap -data-dir /tmp/consul
==> WARNING: Bootstrap mode enabled! Do not enable unless necessary
==> WARNING: It is highly recommended to set GOMAXPROCS higher than 1
==> Starting Consul agent...
==> Starting Consul agent RPC...
==> Consul agent running!
Node name: 'Armons-MacBook-Air'
Datacenter: 'dc1'
Advertise addr: '10.1.10.38'
RPC addr: '127.0.0.1:8400'
HTTP addr: '127.0.0.1:8500'
DNS addr: '127.0.0.1:8600'
Encrypted: false
Server: true (bootstrap: true)
==> Log data will now stream in as it occurs:
2013/10/21 18:57:15 [INFO] Serf agent starting
2013/10/21 18:57:15 [INFO] serf: EventMemberJoin: mitchellh.local 10.0.1.60
2013/10/21 18:57:15 [INFO] Serf agent started
2013/10/21 18:57:15 [INFO] agent: Received event: member-join
[INFO] serf: EventMemberJoin: Armons-MacBook-Air 10.1.10.38
[INFO] serf: EventMemberJoin: Armons-MacBook-Air 10.1.10.38
[INFO] raft: Node at 10.1.10.38:8300 [Follower] entering Follower state
[INFO] consul: adding server for datacenter: dc1, addr: 10.1.10.38:8300
[ERR] agent: failed to sync remote state: rpc error: No cluster leader
[WARN] raft: Heartbeat timeout reached, starting election
[INFO] raft: Node at 10.1.10.38:8300 [Candidate] entering Candidate state
[INFO] raft: Election won. Tally: 1
[INFO] raft: Node at 10.1.10.38:8300 [Leader] entering Leader state
[INFO] consul: cluster leadership acquired
[INFO] consul: New leader elected: Armons-MacBook-Air
[INFO] consul: member 'Armons-MacBook-Air' joined, marking health alive
```
As you can see, the Serf agent has started and has output some log
data. From the log data, you can see that a member has joined the cluster.
This member is yourself.
As you can see, the Consul agent has started and has output some log
data. From the log data, you can see that our agent is running in server mode,
and has claimed leadership of the cluster. Additionally, the local member has
been marked as a healthy member of the cluster.
## Cluster Members
If you run `serf members` in another terminal, you can see the members of
the Serf cluster. You should only see one member (yourself). We'll cover
If you run `consul members` in another terminal, you can see the members of
the Consul cluster. You should only see one member (yourself). We'll cover
joining clusters in the next section.
```
$ serf members
mitchellh.local 10.0.1.60 alive
$ consul members
Armons-MacBook-Air 10.1.10.38:8301 alive role=consul,dc=dc1,vsn=1,vsn_min=1,vsn_max=1,port=8300,bootstrap=1
```
This command, along with many others, communicates with a running Serf
agent via an internal RPC protocol. When starting the Serf agent, you
This command, along with many others, communicates with a running Consul
agent via an internal RPC protocol. When starting the Consul agent, you
may have noticed that it tells you the "RPC addr". This is the address
that commands such as `serf members` use to communicate with the agent.
that commands such as `consul members` use to communicate with the agent.
By default, RPC listens only on loopback, so it is inaccessible outside
of your machine for security reasons.
If you're running multiple Serf agents, you'll have to specify
If you're changed the default RPC address, you'll have to specify
an `-rpc-addr` to both the agent and any commands so that it doesn't
collide with other agents.
It is important to note that the output of the `members` command is
generated by from the [gossip protocol](/docs/internals/gossip.html),
and is eventually consistent. Consul uses this to maintain a strongly
consistent catalog of nodes that can be queried using the [HTTP API](/docs/agent/http.html):
```
$ curl localhost:8500/v1/catalog/nodes
[{"Node":"Armons-MacBook-Air","Address":"10.1.10.38"}]
```
Alternatively, the [DNS interface](/docs/agent/dns.html) could be used:
```
$ dig @127.0.0.1 -p 8600 Armons-MacBook-Air.node.consul
; <<>> DiG 9.8.3-P1 <<>> @127.0.0.1 -p 8600 Armons-MacBook-Air.node.consul
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 63911
;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; WARNING: recursion requested but not available
;; QUESTION SECTION:
;Armons-MacBook-Air.node.consul. IN A
;; ANSWER SECTION:
Armons-MacBook-Air.node.consul. 0 IN A 10.1.10.38
```
## Stopping the Agent
You can use `Ctrl-C` (the interrupt signal) to gracefully halt the agent.
After interrupting the agent, you should see it leave the cluster gracefully
and shut down.
By gracefully leaving, Serf notifies other cluster members that the
By gracefully leaving, Consul notifies other cluster members that the
node _left_. If you had forcibly killed the agent process, other members
of the cluster would have detected that the node _failed_. This can be a
crucial difference depending on what your use case of Serf is. Serf will
automatically try to reconnect to _failed_ nodes, which allows it to recover
from certain network conditions, while _left_ nodes are no longer contacted.
of the cluster would have detected that the node _failed_. When a member leaves,
it's services and checks are removed from the catalog. When a member fails,
it's health is simply marked as critical, but is not removed from the catalog.
Consul will automatically try to reconnect to _failed_ nodes, which allows it
to recover from certain network conditions, while _left_ nodes are no longer contacted.
Additionally, if an agent is operating as a server, a graceful leave is important
to avoid causing a potential availability outage affecting the [consensus protocol](/docs/internals/consensus.html).
See the [guides section](/docs/guides/index.html) to safely add and remove servers.

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---
layout: "intro"
page_title: "Registering Health Checks"
sidebar_current: "gettingstarted-checks"
---
# Registering Health Checks

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website/source/intro/getting-started/install.html.markdown
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@ -1,23 +1,23 @@
---
layout: "intro"
page_title: "Installing Serf"
page_title: "Installing Consul"
sidebar_current: "gettingstarted-install"
---
# Install Serf
# Install Consul
Serf must first be installed on every node that will be a member of a
Serf cluster. To make installation easy, Serf is distributed as a
Consul must first be installed on every node that will be a member of a
Consul cluster. To make installation easy, Consul is distributed as a
[binary package](/downloads.html) for all supported platforms and
architectures. This page will not cover how to compile Serf from
architectures. This page will not cover how to compile Consul from
source.
## Installing Serf
## Installing Consul
To install Serf, find the [appropriate package](/downloads.html) for
your system and download it. Serf is packaged as a "zip" archive.
To install Consul, find the [appropriate package](/downloads.html) for
your system and download it. Consul is packaged as a "zip" archive.
After downloading Serf, unzip the package. Copy the `serf` binary to
After downloading Consul, unzip the package. Copy the `consul` binary to
somewhere on the PATH so that it can be executed. On Unix systems,
`~/bin` and `/usr/local/bin` are common installation directories,
depending on if you want to restrict the install to a single user or
@ -26,28 +26,28 @@ you would like.
## Verifying the Installation
After installing Serf, verify the installation worked by opening a new
terminal session and checking that `serf` is available. By executing
`serf` you should see help output similar to that below:
After installing Consul, verify the installation worked by opening a new
terminal session and checking that `consul` is available. By executing
`consul` you should see help output similar to that below:
```
$ serf
usage: serf [--version] [--help] <command> [<args>]
$ consul
usage: consul [--version] [--help] <command> [<args>]
Available commands are:
agent Runs a Serf agent
event Send a custom event through the Serf cluster
agent Runs a Consul agent
force-leave Forces a member of the cluster to enter the "left" state
join Tell Serf agent to join cluster
info Provides debugging information for operators
join Tell Consul agent to join cluster
keygen Generates a new encryption key
leave Gracefully leaves the Serf cluster and shuts down
members Lists the members of a Serf cluster
monitor Stream logs from a Serf agent
version Prints the Serf version
leave Gracefully leaves the Consul cluster and shuts down
members Lists the members of a Consul cluster
monitor Stream logs from a Consul agent
version Prints the Consul version
```
If you get an error that `serf` could not be found, then your PATH
If you get an error that `consul` could not be found, then your PATH
environmental variable was not setup properly. Please go back and ensure
that your PATH variable contains the directory where Serf was installed.
that your PATH variable contains the directory where Consul was installed.
Otherwise, Serf is installed and ready to go!
Otherwise, Consul is installed and ready to go!

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# Join a Cluster
In the previous page, we started our first agent. While it showed how easy
it is to run Serf, it wasn't very exciting since we simply made a cluster of
it is to run Consul, it wasn't very exciting since we simply made a cluster of
one member. In this page, we'll create a real cluster with multiple members.
When starting a Serf agent, it begins without knowledge of any other node, and is
When starting a Consul agent, it begins without knowledge of any other node, and is
an isolated cluster of one. To learn about other cluster members, the agent must
_join_ an existing cluster. To join an existing cluster, Serf only needs to know
_join_ an existing cluster. To join an existing cluster, only needs to know
about a _single_ existing member. After it joins, the agent will gossip with this
member and quickly discover the other members in the cluster.
## Starting the Agents
First, let's start two agents. Serf agents must all listen on a unique
IP and port pair, so we must bind each agent to a different ports.
To simulate a more realistic cluster, we are using a two node cluster in
Vagrant. The Vagrantfile can be found in the demo section of the repo
[here](https://github.com/hashicorp/consul/tree/master/demo/vagrant-cluster).
The first agent we'll start will listen on `127.0.0.1:7946`. We also will
specify a node name. The node name must be unique and is how a machine
is uniquely identified. By default it is the hostname of the machine, but
since we'll be running multiple agents on a single machine, we'll manually
override it.
We start the first agent on our first node and also specify a node name.
The node name must be unique and is how a machine is uniquely identified.
By default it is the hostname of the machine, but we'll manually override it.
We are also providing a bind address. This is the address that Consul listens on,
and it *must* be accessible by all other nodes in the cluster. The first node
will act as our server in this cluster.
```
$ serf agent -node=agent-one -bind=127.0.0.1:7946
$ consul agent -node=agent-one -bind=172.20.20.10
...
```
Then, in another terminal, start a second agent. We'll bind this agent
to `127.0.0.1:7947`. In addition to overriding the node name, we're also going
to override the RPC address. The RPC address is the address that Serf binds
to for RPC operations. The other `serf` commands communicate with a running
Serf agent over RPC. We left the first agent with the default RPC address
so lets select another for this agent.
Then, in another terminal, start the second agent on the new node.
This time, we set the bind address to match the IP of the second node
as specified in the Vagrantfile. In production, you will generally want
to provide a bind address or interface as well.
```
$ serf agent -node=agent-two -bind=127.0.0.1:7947 -rpc-addr=127.0.0.1:7374
$ consul agent -node=agent-two -bind=172.20.20.11
...
```
At this point, you have two Serf agents running. The two Serf agents
still don't know anything about each other, and are each part of their own
clusters (of one member). You can verify this by running `serf members`
At this point, you have two Consul agents running, one server and one client.
The two Consul agents still don't know anything about each other, and are each part of their own
clusters (of one member). You can verify this by running `consul members`
against each agent and noting that only one member is a part of each.
## Joining a Cluster
@ -55,34 +55,34 @@ Now, let's tell the first agent to join the second agent by running
the following command in a new terminal:
```
$ serf join 127.0.0.1:7947
$ consul join 127.0.0.1:7947
Successfully joined cluster by contacting 1 nodes.
```
You should see some log output in each of the agent logs. If you read
carefully, you'll see that they received join information. If you
run `serf members` against each agent, you'll see that both agents now
run `consul members` against each agent, you'll see that both agents now
know about each other:
```
$ serf members
$ consul members
agent-one 127.0.0.1:7946 alive
agent-two 127.0.0.1:7947 alive
$ serf members -rpc-addr=127.0.0.1:7374
$ consul members -rpc-addr=127.0.0.1:7374
agent-two 127.0.0.1:7947 alive
agent-one 127.0.0.1:4946 alive
```
<div class="alert alert-block alert-info">
<p><strong>Remember:</strong> To join a cluster, a Serf agent needs to only
<p><strong>Remember:</strong> To join a cluster, a Consul agent needs to only
learn about <em>one existing member</em>. After joining the cluster, the
agents gossip with each other to propagate full membership information.
</p>
</div>
In addition to using `serf join` you can use the `-join` flag on
`serf agent` to join a cluster as part of starting up the agent.
In addition to using `consul join` you can use the `-join` flag on
`consul agent` to join a cluster as part of starting up the agent.
## Leaving a Cluster
@ -91,3 +91,4 @@ To leave the cluster, you can either gracefully quit an agent (using
the node to transition into the _left_ state, otherwise other nodes
will detect it as having _failed_. The difference is covered
in more detail [here](/intro/getting-started/agent.html#toc_3).

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---
layout: "intro"
page_title: "Key/Value Data"
sidebar_current: "gettingstarted-kv"
---
# Key/Value Data

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---
layout: "intro"
page_title: "Registering Services"
sidebar_current: "gettingstarted-services"
---
# Registering Services

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@ -62,6 +62,10 @@
<a href="/intro/getting-started/checks.html">Health Checks</a>
</li>
<li<%= sidebar_current("gettingstarted-kv") %>>
<a href="/intro/getting-started/kv.html">Key/Value Data</a>
</li>
<li<%= sidebar_current("gettingstarted-nextsteps") %>>
<a href="/intro/getting-started/next-steps.html">Next Steps</a>
</li>