Merge pull request #1550 from hashicorp/f-devmode

Add a `-dev` mode for easy prototyping

command/agent/agent.go

@@ -124,7 +124,7 @@ func Create(config *Config, logOutput io.Writer) (*Agent, error) {
 	if config.Datacenter == "" {
 		return nil, fmt.Errorf("Must configure a Datacenter")
 	}
-	if config.DataDir == "" {
+	if config.DataDir == "" && !config.DevMode {
 		return nil, fmt.Errorf("Must configure a DataDir")
 	}
 
@@ -227,6 +227,9 @@ func (a *Agent) consulConfig() *consul.Config {
 		base = consul.DefaultConfig()
 	}
 
+	// Apply dev mode
+	base.DevMode = a.config.DevMode
+
 	// Override with our config
 	if a.config.Datacenter != "" {
 		base.Datacenter = a.config.Datacenter
@@ -748,7 +751,7 @@ func (a *Agent) AddService(service *structs.NodeService, chkTypes CheckTypes, pe
 	a.state.AddService(service, token)
 
 	// Persist the service to a file
-	if persist {
+	if persist && !a.config.DevMode {
 		if err := a.persistService(service); err != nil {
 			return err
 		}
@@ -958,7 +961,7 @@ func (a *Agent) AddCheck(check *structs.HealthCheck, chkType *CheckType, persist
 	a.state.AddCheck(check, token)
 
 	// Persist the check
-	if persist {
+	if persist && !a.config.DevMode {
 		return a.persistCheck(check, chkType)
 	}
 
@@ -1022,6 +1025,10 @@ func (a *Agent) UpdateCheck(checkID, status, output string) error {
 	// Set the status through CheckTTL to reset the TTL
 	check.SetStatus(status, output)
 
+	if a.config.DevMode {
+		return nil
+	}
+
 	// Always persist the state for TTL checks
 	if err := a.persistCheckState(check, status, output); err != nil {
 		return fmt.Errorf("failed persisting state for check %q: %s", checkID, err)

command/agent/command.go

@@ -60,12 +60,14 @@ func (c *Command) readConfig() *Config {
 	var retryInterval string
 	var retryIntervalWan string
 	var dnsRecursors []string
+	var dev bool
 	cmdFlags := flag.NewFlagSet("agent", flag.ContinueOnError)
 	cmdFlags.Usage = func() { c.Ui.Output(c.Help()) }
 
 	cmdFlags.Var((*AppendSliceValue)(&configFiles), "config-file", "json file to read config from")
 	cmdFlags.Var((*AppendSliceValue)(&configFiles), "config-dir", "directory of json files to read")
 	cmdFlags.Var((*AppendSliceValue)(&dnsRecursors), "recursor", "address of an upstream DNS server")
+	cmdFlags.BoolVar(&dev, "dev", false, "development server mode")
 
 	cmdFlags.StringVar(&cmdConfig.LogLevel, "log-level", "", "log level")
 	cmdFlags.StringVar(&cmdConfig.NodeName, "node", "", "node name")
@@ -137,7 +139,13 @@ func (c *Command) readConfig() *Config {
 		cmdConfig.RetryIntervalWan = dur
 	}
 
-	config := DefaultConfig()
+	var config *Config
+	if dev {
+		config = DevConfig()
+	} else {
+		config = DefaultConfig()
+	}
+
 	if len(configFiles) > 0 {
 		fileConfig, err := ReadConfigPaths(configFiles)
 		if err != nil {
@@ -162,7 +170,7 @@ func (c *Command) readConfig() *Config {
 	}
 
 	// Ensure we have a data directory
-	if config.DataDir == "" {
+	if config.DataDir == "" && !dev {
 		c.Ui.Error("Must specify data directory using -data-dir")
 		return nil
 	}

command/agent/config.go

@@ -94,6 +94,10 @@ type DNSConfig struct {
 // Some of this is configurable as CLI flags, but most must
 // be set using a configuration file.
 type Config struct {
+	// DevMode enables a fast-path mode of opertaion to bring up an in-memory
+	// server with minimal configuration. Useful for developing Consul.
+	DevMode bool `mapstructure:"-"`
+
 	// Bootstrap is used to bring up the first Consul server, and
 	// permits that node to elect itself leader
 	Bootstrap bool `mapstructure:"bootstrap"`
@@ -521,6 +525,18 @@ func DefaultConfig() *Config {
 	}
 }
 
+// DevConfig is used to return a set of configuration to use for dev mode.
+func DevConfig() *Config {
+	conf := DefaultConfig()
+	conf.DevMode = true
+	conf.LogLevel = "DEBUG"
+	conf.Server = true
+	conf.EnableDebug = true
+	conf.DisableAnonymousSignature = true
+	conf.EnableUi = true
+	return conf
+}
+
 // EncryptBytes returns the encryption key configured.
 func (c *Config) EncryptBytes() ([]byte, error) {
 	return base64.StdEncoding.DecodeString(c.EncryptKey)

consul/config.go

@@ -54,6 +54,9 @@ type Config struct {
 	// DataDir is the directory to store our state in
 	DataDir string
 
+	// DevMode is used to enable a development server mode.
+	DevMode bool
+
 	// Node name is the name we use to advertise. Defaults to hostname.
 	NodeName string
 

consul/server.go

@@ -110,6 +110,7 @@ type Server struct {
 	raftPeers     raft.PeerStore
 	raftStore     *raftboltdb.BoltStore
 	raftTransport *raft.NetworkTransport
+	raftInmem     *raft.InmemStore
 
 	// reconcileCh is used to pass events from the serf handler
 	// into the leader manager, so that the strong state can be
@@ -173,7 +174,7 @@ func NewServer(config *Config) (*Server, error) {
 	}
 
 	// Check for a data directory!
-	if config.DataDir == "" {
+	if config.DataDir == "" && !config.DevMode {
 		return nil, fmt.Errorf("Config must provide a DataDir")
 	}
 
@@ -301,7 +302,9 @@ func (s *Server) setupSerf(conf *serf.Config, ch chan serf.Event, path string, w
 	conf.MemberlistConfig.LogOutput = s.config.LogOutput
 	conf.LogOutput = s.config.LogOutput
 	conf.EventCh = ch
+	if !s.config.DevMode {
 		conf.SnapshotPath = filepath.Join(s.config.DataDir, path)
+	}
 	conf.ProtocolVersion = protocolVersionMap[s.config.ProtocolVersion]
 	conf.RejoinAfterLeave = s.config.RejoinAfterLeave
 	if wan {
@@ -327,7 +330,7 @@ func (s *Server) setupSerf(conf *serf.Config, ch chan serf.Event, path string, w
 // setupRaft is used to setup and initialize Raft
 func (s *Server) setupRaft() error {
 	// If we are in bootstrap mode, enable a single node cluster
-	if s.config.Bootstrap {
+	if s.config.Bootstrap || s.config.DevMode {
 		s.config.RaftConfig.EnableSingleNode = true
 	}
 
@@ -338,6 +341,24 @@ func (s *Server) setupRaft() error {
 		return err
 	}
 
+	// Create a transport layer
+	trans := raft.NewNetworkTransport(s.raftLayer, 3, 10*time.Second, s.config.LogOutput)
+	s.raftTransport = trans
+
+	var log raft.LogStore
+	var stable raft.StableStore
+	var snap raft.SnapshotStore
+	var peers raft.PeerStore
+
+	if s.config.DevMode {
+		store := raft.NewInmemStore()
+		s.raftInmem = store
+		stable = store
+		log = store
+		snap = raft.NewDiscardSnapshotStore()
+		peers = &raft.StaticPeers{}
+		s.raftPeers = peers
+	} else {
 		// Create the base raft path
 		path := filepath.Join(s.config.DataDir, raftState)
 		if err := ensurePath(path, true); err != nil {
@@ -350,6 +371,7 @@ func (s *Server) setupRaft() error {
 			return err
 		}
 		s.raftStore = store
+		stable = store
 
 		// Wrap the store in a LogCache to improve performance
 		cacheStore, err := raft.NewLogCache(raftLogCacheSize, store)
@@ -357,6 +379,7 @@ func (s *Server) setupRaft() error {
 			store.Close()
 			return err
 		}
+		log = cacheStore
 
 		// Create the snapshot store
 		snapshots, err := raft.NewFileSnapshotStore(path, snapshotsRetained, s.config.LogOutput)
@@ -364,19 +387,20 @@ func (s *Server) setupRaft() error {
 			store.Close()
 			return err
 		}
-
+		snap = snapshots
-	// Create a transport layer
-	trans := raft.NewNetworkTransport(s.raftLayer, 3, 10*time.Second, s.config.LogOutput)
-	s.raftTransport = trans
 
 		// Setup the peer store
 		s.raftPeers = raft.NewJSONPeers(path, trans)
+		peers = s.raftPeers
+	}
 
 	// Ensure local host is always included if we are in bootstrap mode
 	if s.config.Bootstrap {
 		peers, err := s.raftPeers.Peers()
 		if err != nil {
-			store.Close()
+			if s.raftStore != nil {
+				s.raftStore.Close()
+			}
 			return err
 		}
 		if !raft.PeerContained(peers, trans.LocalAddr()) {
@@ -388,10 +412,12 @@ func (s *Server) setupRaft() error {
 	s.config.RaftConfig.LogOutput = s.config.LogOutput
 
 	// Setup the Raft store
-	s.raft, err = raft.NewRaft(s.config.RaftConfig, s.fsm, cacheStore, store,
+	s.raft, err = raft.NewRaft(s.config.RaftConfig, s.fsm, log, stable,
-		snapshots, s.raftPeers, trans)
+		snap, s.raftPeers, trans)
 	if err != nil {
-		store.Close()
+		if s.raftStore != nil {
+			s.raftStore.Close()
+		}
 		trans.Close()
 		return err
 	}
@@ -484,7 +510,9 @@ func (s *Server) Shutdown() error {
 		if err := future.Error(); err != nil {
 			s.logger.Printf("[WARN] consul: Error shutting down raft: %s", err)
 		}
+		if s.raftStore != nil {
 			s.raftStore.Close()
+		}
 
 		// Clear the peer set on a graceful leave to avoid
 		// triggering elections on a rejoin.

website/source/docs/agent/options.html.markdown

@@ -124,6 +124,12 @@ The options below are all specified on the command-line.
   the use of filesystem locking, meaning some types of mounted folders (e.g. VirtualBox
   shared folders) may not be suitable.
 
+* <a name="_dev"></a><a href="#_dev">`-dev`</a> - Enable development server
+  mode. This is useful for quickly starting a Consul agent with all persistence
+  options turned off, enabling an in-memory server which can be used for rapid
+  prototyping or developing against the API. This mode is **not** intended for
+  production use as it does not write any data to disk.
+
 * <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

website/source/intro/getting-started/agent.html.markdown

@@ -2,8 +2,11 @@
 layout: "intro"
 page_title: "Run the Agent"
 sidebar_current: "gettingstarted-agent"
-description: |-
+description: >
-  After Consul is installed, the agent must be run. The agent can either run in server or client mode. Each datacenter must have at least one server, though a cluster of 3 or 5 servers is recommended. A single server deployment is highly discouraged as data loss is inevitable in a failure scenario.
+  The Consul agent can run in either server or client mode. Each datacenter
+  must have at least one server, though a cluster of 3 or 5 servers is
+  recommended. A single server deployment is highly discouraged in production
+  as data loss is inevitable in a failure scenario.
 ---
 
 # Run the Consul Agent
@@ -22,34 +25,45 @@ For more detail on bootstrapping a datacenter, see
 
 ## Starting the Agent
 
-For simplicity, we'll run a single Consul agent in server mode:
+For simplicity, we'll start the Consul agent in development mode for now. This
+mode is useful for bringing up a single-node Consul environment quickly and
+easily. It is **not** intended to be used in production as it does not persist
+any state.
 
 ```text
-$ consul agent -server -bootstrap-expect 1 -data-dir /tmp/consul
+$ consul agent -dev
-==> WARNING: BootstrapExpect Mode is specified as 1; this is the same as Bootstrap mode.
-==> WARNING: Bootstrap mode enabled! Do not enable unless necessary
 ==> Starting Consul agent...
 ==> Starting Consul agent RPC...
 ==> Consul agent running!
          Node name: 'Armons-MacBook-Air'
         Datacenter: 'dc1'
-          Server: true (bootstrap: true)
+            Server: true (bootstrap: false)
-     Client Addr: 127.0.0.1 (HTTP: 8500, DNS: 8600, RPC: 8400)
+       Client Addr: 127.0.0.1 (HTTP: 8500, HTTPS: -1, DNS: 8600, RPC: 8400)
-    Cluster Addr: 10.1.10.38 (LAN: 8301, WAN: 8302)
+      Cluster Addr: 172.20.20.11 (LAN: 8301, WAN: 8302)
+    Gossip encrypt: false, RPC-TLS: false, TLS-Incoming: false
+             Atlas: <disabled>
 
 ==> Log data will now stream in as it occurs:
 
-[INFO] serf: EventMemberJoin: Armons-MacBook-Air.local 10.1.10.38
+[INFO] raft: Node at 172.20.20.11:8300 [Follower] entering Follower state
-[INFO] raft: Node at 10.1.10.38:8300 [Follower] entering Follower state
+[INFO] serf: EventMemberJoin: Armons-MacBook-Air 172.20.20.11
-[INFO] consul: adding server for datacenter: dc1, addr: 10.1.10.38:8300
+[INFO] consul: adding LAN server Armons-MacBook-Air (Addr: 172.20.20.11:8300) (DC: dc1)
-[ERR] agent: failed to sync remote state: rpc error: No cluster leader
+[INFO] serf: EventMemberJoin: Armons-MacBook-Air.dc1 172.20.20.11
+[INFO] consul: adding WAN server Armons-MacBook-Air.dc1 (Addr: 172.20.20.11:8300) (DC: dc1)
+[ERR] agent: failed to sync remote state: 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: Node at 172.20.20.11:8300 [Candidate] entering Candidate state
+[DEBUG] raft: Votes needed: 1
+[DEBUG] raft: Vote granted. Tally: 1
 [INFO] raft: Election won. Tally: 1
-[INFO] raft: Node at 10.1.10.38:8300 [Leader] entering Leader state
+[INFO] raft: Node at 172.20.20.11:8300 [Leader] entering Leader state
+[INFO] raft: Disabling EnableSingleNode (bootstrap)
 [INFO] consul: cluster leadership acquired
+[DEBUG] raft: Node 172.20.20.11:8300 updated peer set (2): [172.20.20.11:8300]
+[DEBUG] consul: reset tombstone GC to index 2
 [INFO] consul: New leader elected: Armons-MacBook-Air
 [INFO] consul: member 'Armons-MacBook-Air' joined, marking health alive
+[INFO] agent: Synced service 'consul'
 ```
 
 As you can see, the Consul agent has started and has output some log
@@ -70,8 +84,8 @@ section, but for now, you should only see one member (yourself):
 
 ```text
 $ consul members
-Node                    Address             Status  Type    Build  Protocol
+Node                Address            Status  Type    Build     Protocol  DC
-Armons-MacBook-Air      10.1.10.38:8301     alive   server  0.5.1  2
+Armons-MacBook-Air  172.20.20.11:8301  alive   server  0.6.1dev  2         dc1
 ```
 
 The output shows our own node, the address it is running on, its
@@ -87,7 +101,7 @@ request to the Consul servers:
 
 ```text
 $ curl localhost:8500/v1/catalog/nodes
-[{"Node":"Armons-MacBook-Air","Address":"10.1.10.38"}]
+[{"Node":"Armons-MacBook-Air","Address":"172.20.20.11","CreateIndex":3,"ModifyIndex":4}]
 ```
 
 In addition to the HTTP API, the [DNS interface](/docs/agent/dns.html) can
@@ -104,7 +118,7 @@ $ dig @127.0.0.1 -p 8600 Armons-MacBook-Air.node.consul
 ;Armons-MacBook-Air.node.consul.	IN	A
 
 ;; ANSWER SECTION:
-Armons-MacBook-Air.node.consul.	0 IN	A	10.1.10.38
+Armons-MacBook-Air.node.consul.	0 IN	A	172.20.20.11
 ```
 
 ## <a name="stopping"></a>Stopping the Agent

website/source/intro/getting-started/consul.d/web.json

@@ -0,0 +1 @@
+{"service": {"name": "web", "tags": ["rails"], "port": 80}}

website/source/intro/getting-started/join.html.markdown

@@ -2,8 +2,11 @@
 layout: "intro"
 page_title: "Consul Cluster"
 sidebar_current: "gettingstarted-join"
-description: |-
+description: >
-  We've started our first agent and registered and queried a service on that agent. This showed how easy it is to use Consul but didn't show how this could be extended to a scalable, production-grade service discovery infrastructure. In this step, we'll create our first real cluster with multiple members.
+  When a Consul agent is started, it begins as an isolated cluster of its own.
+  To learn about other cluster members, the agent must join one or more other
+  nodes using a provided join address. In this step, we will set up a two-node
+  cluster and join the nodes together.
 ---
 
 # Consul Cluster
@@ -40,6 +43,12 @@ of our cluster. We start by logging in to the first node:
 $ vagrant ssh n1
 ```
 
+In our previous examples, we used the [`-dev`
+flag](/docs/agent/options.html#_dev) to quickly set up a development server.
+However, this is not sufficient for use in a clustered environment. We will
+omit the `-dev` flag from here on, and instead specify our clustering flags as
+outlined below.
+
 Each node in a cluster must have a unique name. By default, Consul uses the
 hostname of the machine, but we'll manually override it using the [`-node`
 command-line option](/docs/agent/options.html#_node).
@@ -53,9 +62,17 @@ multiple interfaces, so specifying a `bind` address assures that you will
 never bind Consul to the wrong interface.
 
 The first node will act as our sole server in this cluster, and we indicate
-this with the [`server` switch](/docs/agent/options.html#_server). Finally, we
+this with the [`server` switch](/docs/agent/options.html#_server).
-add the [`config-dir` flag](/docs/agent/options.html#_config_dir), marking
+
-where service and check definitions can be found.
+The [`-bootstrap-expect` flag](/docs/agent/options.html#_bootstrap_expect)
+hints to the Consul server the number of additional server nodes we are
+expecting to join. The purpose of this flag is to delay the bootstrapping of
+the replicated log until the expected number of servers has successfully joined.
+You can read more about this in the [bootstrapping
+guide](/docs/guides/bootstrapping.html).
+
+Finally, we add the [`config-dir` flag](/docs/agent/options.html#_config_dir),
+marking where service and check definitions can be found.
 
 All together, these settings yield a
 [`consul agent`](/docs/commands/agent.html) command like this:

website/source/intro/getting-started/services.html.markdown

@@ -2,8 +2,11 @@
 layout: "intro"
 page_title: "Registering Services"
 sidebar_current: "gettingstarted-services"
-description: |-
+description: >
-  In the previous step, we ran our first agent, saw the cluster members (well, our cluster member), and queried that node. Now, we'll register our first service and query that service.
+  A service can be registered either by providing a service definition or by
+  making the appropriate calls to the HTTP API. A configuration file is the
+  most common, so we will use this approach to register a service, and then
+  query that service using the REST API and DNS interfaces.
 ---
 
 # Registering Services
@@ -44,8 +47,7 @@ $ echo '{"service": {"name": "web", "tags": ["rails"], "port": 80}}' \
 Now, restart the agent, providing the configuration directory:
 
 ```text
-$ consul agent -server -bootstrap-expect 1 -data-dir /tmp/consul \
+$ consul agent -dev -config-dir /etc/consul.d
-    -config-dir /etc/consul.d
 ==> Starting Consul agent...
 ...
     [INFO] agent: Synced service 'web'
@@ -53,7 +55,8 @@ $ consul agent -server -bootstrap-expect 1 -data-dir /tmp/consul \
 ```
 
 You'll notice in the output that it "synced" the web service. This means
-that it loaded the information from the configuration.
+that the agent loaded the service definition from the configuration file,
+and has successfully registered it in the service catalog.
 
 If you wanted to register multiple services, you could create multiple
 service definition files in the Consul configuration directory.
@@ -100,10 +103,10 @@ $ dig @127.0.0.1 -p 8600 web.service.consul SRV
 ;web.service.consul.		IN	SRV
 
 ;; ANSWER SECTION:
-web.service.consul. 0	IN	SRV	1 1 80 agent-one.node.dc1.consul.
+web.service.consul.	0	IN	SRV	1 1 80 Armons-MacBook-Air.node.dc1.consul.
 
 ;; ADDITIONAL SECTION:
-agent-one.node.dc1.consul. 0	IN	A	172.20.20.11
+Armons-MacBook-Air.node.dc1.consul. 0 IN A	172.20.20.11
 ```
 
 The `SRV` record says that the web service is running on port 80 and exists on