Consul: 3: getting started with agent

Consul is very simple to use. This article continues to introduce the usage of Consul Agent in an example way.

Preparation beforehand

liumiaocn:~ liumiao$ consul --version
Consul v1.7.1
Protocol 2 spoken by default, understands 2 to 3 (agent will automatically use protocol >2 when speaking to compatible agents)
liumiaocn:~ liumiao$

Start Consul Agent

To be able to use Consul, you need to start the Consul Agent after installation. Execute the command as follows:

Execute command: consumer agent - Dev

liumiaocn:~ liumiao$ consul agent -dev
==> Starting Consul agent...
           Version: 'v1.7.1'
           Node ID: 'e95df364-000e-e590-6bd4-ceb947b8c90b'
         Node name: 'liumiaocn'
        Datacenter: 'dc1' (Segment: '<all>')
            Server: true (Bootstrap: false)
       Client Addr: [127.0.0.1] (HTTP: 8500, HTTPS: -1, gRPC: 8502, DNS: 8600)
      Cluster Addr: 127.0.0.1 (LAN: 8301, WAN: 8302)
           Encrypt: Gossip: false, TLS-Outgoing: false, TLS-Incoming: false, Auto-Encrypt-TLS: false

Detailed log information is as follows

==> Log data will now stream in as it occurs:

    2020-02-29T06:58:17.094+0800 [DEBUG] agent: Using random ID as node ID: id=e95df364-000e-e590-6bd4-ceb947b8c90b
    2020-02-29T06:58:17.094+0800 [DEBUG] agent.tlsutil: Update: version=1
    2020-02-29T06:58:17.095+0800 [DEBUG] agent.tlsutil: OutgoingRPCWrapper: version=1
    2020-02-29T06:58:17.096+0800 [INFO]  agent.server.raft: initial configuration: index=1 servers="[{Suffrage:Voter ID:e95df364-000e-e590-6bd4-ceb947b8c90b Address:127.0.0.1:8300}]"
    2020-02-29T06:58:17.096+0800 [INFO]  agent.server.raft: entering follower state: follower="Node at 127.0.0.1:8300 [Follower]" leader=
    2020-02-29T06:58:17.096+0800 [INFO]  agent.server.serf.wan: serf: EventMemberJoin: liumiaocn.dc1 127.0.0.1
    2020-02-29T06:58:17.096+0800 [INFO]  agent.server.serf.lan: serf: EventMemberJoin: liumiaocn 127.0.0.1
    2020-02-29T06:58:17.096+0800 [INFO]  agent.server: Adding LAN server: server="liumiaocn (Addr: tcp/127.0.0.1:8300) (DC: dc1)"
    2020-02-29T06:58:17.096+0800 [INFO]  agent.server: Handled event for server in area: event=member-join server=liumiaocn.dc1 area=wan
    2020-02-29T06:58:17.097+0800 [INFO]  agent: Started DNS server: address=127.0.0.1:8600 network=tcp
    2020-02-29T06:58:17.097+0800 [INFO]  agent: Started DNS server: address=127.0.0.1:8600 network=udp
    2020-02-29T06:58:17.097+0800 [INFO]  agent: Started HTTP server: address=127.0.0.1:8500 network=tcp
    2020-02-29T06:58:17.097+0800 [INFO]  agent: Started gRPC server: address=127.0.0.1:8502 network=tcp
    2020-02-29T06:58:17.097+0800 [INFO]  agent: started state syncer
==> Consul agent running!
    2020-02-29T06:58:17.161+0800 [WARN]  agent.server.raft: heartbeat timeout reached, starting election: last-leader=
    2020-02-29T06:58:17.161+0800 [INFO]  agent.server.raft: entering candidate state: node="Node at 127.0.0.1:8300 [Candidate]" term=2
    2020-02-29T06:58:17.161+0800 [DEBUG] agent.server.raft: votes: needed=1
    2020-02-29T06:58:17.161+0800 [DEBUG] agent.server.raft: vote granted: from=e95df364-000e-e590-6bd4-ceb947b8c90b term=2 tally=1
    2020-02-29T06:58:17.161+0800 [INFO]  agent.server.raft: election won: tally=1
    2020-02-29T06:58:17.161+0800 [INFO]  agent.server.raft: entering leader state: leader="Node at 127.0.0.1:8300 [Leader]"
    2020-02-29T06:58:17.161+0800 [INFO]  agent.server: cluster leadership acquired
    2020-02-29T06:58:17.162+0800 [INFO]  agent.server: New leader elected: payload=liumiaocn
    2020-02-29T06:58:17.162+0800 [DEBUG] connect.ca.consul: consul CA provider configured: id=07:80:c8:de:f6:41:86:29:8f:9c:b8:17:d6:48:c2:d5:c5:5c:7f:0c:03:f7:cf:97:5a:a7:c1:68:aa:23:ae:81 is_primary=true
    2020-02-29T06:58:17.173+0800 [INFO]  agent.server.connect: initialized primary datacenter CA with provider: provider=consul
    2020-02-29T06:58:17.173+0800 [INFO]  agent.leader: started routine: routine="CA root pruning"
    2020-02-29T06:58:17.173+0800 [DEBUG] agent.server: Skipping self join check for node since the cluster is too small: node=liumiaocn
    2020-02-29T06:58:17.173+0800 [INFO]  agent.server: member joined, marking health alive: member=liumiaocn
    2020-02-29T06:58:17.499+0800 [DEBUG] agent: Skipping remote check since it is managed automatically: check=serfHealth
    2020-02-29T06:58:17.499+0800 [INFO]  agent: Synced node info
    2020-02-29T06:58:17.499+0800 [DEBUG] agent: Node info in sync
    2020-02-29T06:58:19.165+0800 [DEBUG] agent.tlsutil: OutgoingRPCWrapper: version=1
    2020-02-29T06:58:20.295+0800 [DEBUG] agent: Skipping remote check since it is managed automatically: check=serfHealth
    2020-02-29T06:58:20.295+0800 [DEBUG] agent: Node info in sync

Note: Consul will use hostname as the default node name, such as liumiaocn in the example of this article. However, if the hostname contains,. The DNS query in Consul will not work. In this case, you need to use the - node option to set the node name.

Query node information

Start another terminal and execute the following command to confirm the Consul node information

Execute command: consumer members

liumiaocn:~ liumiao$ consul members
Node       Address         Status  Type    Build  Protocol  DC   Segment
liumiaocn  127.0.0.1:8301  alive   server  1.7.1  2         dc1  <all>
liumiaocn:~ liumiao$

During execution, you can confirm the following similar information:

    2020-02-29T07:10:25.609+0800 [DEBUG] agent.http: Request finished: method=GET url=/v1/agent/members?segment=_all from=127.0.0.1:53489 latency=113.689µs

Use the detailed option to confirm more detailed information

liumiaocn:~ liumiao$ consul members -detailed
Node       Address         Status  Tags
liumiaocn  127.0.0.1:8301  alive   acls=0,build=1.7.1:2cf0a3c8,dc=dc1,id=e95df364-000e-e590-6bd4-ceb947b8c90b,port=8300,raft_vsn=3,role=consul,segment=<all>,vsn=2,vsn_max=3,vsn_min=2,wan_join_port=8302
liumiaocn:~ liumiao$

Stop Agent

Start another terminal and execute the following command to stop the Agent. To be exact, disconnect this node from the Consul cluster and stop the Consul Agent

Execute command: consumer leave

An example of stopping command execution is as follows:

liumiaocn:~ liumiao$ consul leave
Graceful leave complete
liumiaocn:~ liumiao$

The log information is as follows:

    2020-02-29T07:12:20.113+0800 [INFO]  agent.server: server starting leave
    2020-02-29T07:12:20.113+0800 [INFO]  agent.server.serf.wan: serf: EventMemberLeave: liumiaocn.dc1 127.0.0.1
    2020-02-29T07:12:20.113+0800 [INFO]  agent.server: Handled event for server in area: event=member-leave server=liumiaocn.dc1 area=wan
    2020-02-29T07:12:20.113+0800 [INFO]  agent.server.router.manager: shutting down
    2020-02-29T07:12:23.113+0800 [INFO]  agent.server.serf.lan: serf: EventMemberLeave: liumiaocn 127.0.0.1
    2020-02-29T07:12:23.113+0800 [INFO]  agent.server: Removing LAN server: server="liumiaocn (Addr: tcp/127.0.0.1:8300) (DC: dc1)"
    2020-02-29T07:12:23.113+0800 [WARN]  agent.server: deregistering self should be done by follower: name=liumiaocn
    2020-02-29T07:12:23.138+0800 [ERROR] agent.server.autopilot: Error updating cluster health: error="error getting server raft protocol versions: No servers found"
    2020-02-29T07:12:25.138+0800 [ERROR] agent.server.autopilot: Error updating cluster health: error="error getting server raft protocol versions: No servers found"
    2020-02-29T07:12:26.113+0800 [INFO]  agent.server: Waiting to drain RPC traffic: drain_time=5s
    2020-02-29T07:12:27.137+0800 [ERROR] agent.server.autopilot: Error updating cluster health: error="error getting server raft protocol versions: No servers found"
    2020-02-29T07:12:27.137+0800 [ERROR] agent.server.autopilot: Error promoting servers: error="error getting server raft protocol versions: No servers found"
    2020-02-29T07:12:29.137+0800 [ERROR] agent.server.autopilot: Error updating cluster health: error="error getting server raft protocol versions: No servers found"
    2020-02-29T07:12:31.116+0800 [INFO]  agent: Requesting shutdown
    2020-02-29T07:12:31.116+0800 [INFO]  agent.server: shutting down server
    2020-02-29T07:12:31.116+0800 [DEBUG] agent.leader: stopping routine: routine="CA root pruning"
    2020-02-29T07:12:31.116+0800 [DEBUG] agent.leader: stopped routine: routine="CA root pruning"
    2020-02-29T07:12:31.116+0800 [INFO]  agent: consul server down
    2020-02-29T07:12:31.116+0800 [INFO]  agent: shutdown complete
    2020-02-29T07:12:31.117+0800 [DEBUG] agent.http: Request finished: method=PUT url=/v1/agent/leave from=127.0.0.1:53565 latency=11.004059585s
    2020-02-29T07:12:31.117+0800 [INFO]  agent: Stopping server: protocol=DNS address=127.0.0.1:8600 network=tcp
    2020-02-29T07:12:31.117+0800 [INFO]  agent: Stopping server: protocol=DNS address=127.0.0.1:8600 network=udp
    2020-02-29T07:12:31.117+0800 [INFO]  agent: Stopping server: protocol=HTTP address=127.0.0.1:8500 network=tcp
    2020-02-29T07:12:31.117+0800 [INFO]  agent: Waiting for endpoints to shut down
    2020-02-29T07:12:31.117+0800 [INFO]  agent: Endpoints down
    2020-02-29T07:12:31.117+0800 [INFO]  agent: Exit code: code=0
liumiaocn:~ liumiao$

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Added by harnacks on Sat, 29 Feb 2020 07:58:19 +0200

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Consul: 3: getting started with agent

Preparation beforehand

Start Consul Agent

Query node information

Stop Agent

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