» consul Stanza

Placement consul

The consul stanza configures the Nomad agent's communication with Consul for service discovery and key-value integration. When configured, tasks can register themselves with Consul, and the Nomad cluster can automatically bootstrap itself.

consul {
  address = "127.0.0.1:8500"
  auth    = "admin:password"
  token   = "abcd1234"
}

A default consul stanza is automatically merged with all Nomad agent configurations. These sane defaults automatically enable Consul integration if Consul is detected on the system. This allows for seamless bootstrapping of the cluster with zero configuration. To put it another way: if you have a Consul agent running on the same host as the Nomad agent with the default configuration, Nomad will automatically connect and configure with Consul.

An important requirement is that each Nomad agent talks to a unique Consul agent. Nomad agents should be configured to talk to Consul agents and not Consul servers. If you are observing flapping services, you may have have multiple Nomad agents talking to the same Consul agent. As such avoid configuring Nomad to talk to Consul via DNS such as consul.service.consul

» consul Parameters

  • address (string: "127.0.0.1:8500") - Specifies the address to the local Consul agent, given in the format host:port. Supports Unix sockets with the format: unix:///tmp/consul/consul.sock

  • auth (string: "") - Specifies the HTTP Basic Authentication information to use for access to the Consul Agent, given in the format username:password.

  • auto_advertise (bool: true) - Specifies if Nomad should advertise its services in Consul. The services are named according to server_service_name and client_service_name. Nomad servers and clients advertise their respective services, each tagged appropriately with either http or rpc tag. Nomad servers also advertise a serf tagged service.

  • ca_file (string: "") - Specifies an optional path to the CA certificate used for Consul communication. This defaults to the system bundle if unspecified.

  • cert_file (string: "") - Specifies the path to the certificate used for Consul communication. If this is set then you need to also set key_file.

  • checks_use_advertise (bool: false) - Specifies if Consul health checks should bind to the advertise address. By default, this is the bind address.

  • client_auto_join (bool: true) - Specifies if the Nomad clients should automatically discover servers in the same region by searching for the Consul service name defined in the server_service_name option. The search occurs if the client is not registered with any servers or it is unable to heartbeat to the leader of the region, in which case it may be partitioned and searches for other servers.

  • client_service_name (string: "nomad-client") - Specifies the name of the service in Consul for the Nomad clients.

  • client_http_check_name (string: "Nomad Client HTTP Check") - Specifies the HTTP health check name in Consul for the Nomad clients.

  • key_file (string: "") - Specifies the path to the private key used for Consul communication. If this is set then you need to also set cert_file.

  • server_service_name (string: "nomad") - Specifies the name of the service in Consul for the Nomad servers.

  • server_http_check_name (string: "Nomad Server HTTP Check") - Specifies the HTTP health check name in Consul for the Nomad servers.

  • server_serf_check_name (string: "Nomad Server Serf Check") - Specifies the Serf health check name in Consul for the Nomad servers.

  • server_rpc_check_name (string: "Nomad Server RPC Check") - Specifies the RPC health check name in Consul for the Nomad servers.

  • server_auto_join (bool: true) - Specifies if the Nomad servers should automatically discover and join other Nomad servers by searching for the Consul service name defined in the server_service_name option. This search only happens if the server does not have a leader.

  • ssl (bool: false) - Specifies if the transport scheme should use HTTPS to communicate with the Consul agent.

  • token (string: "") - Specifies the token used to provide a per-request ACL token. This option overrides the Consul Agent's default token. If the token is not set here or on the Consul agent, it will default to Consul's anonymous policy, which may or may not allow writes.

  • verify_ssl (bool: true)- Specifies if SSL peer verification should be used when communicating to the Consul API client over HTTPS

If the local Consul agent is configured and accessible by the Nomad agents, the Nomad cluster will automatically bootstrap provided server_auto_join, client_auto_join, and auto_advertise are all enabled (which is the default).

» consul Examples

» Default

This example shows the default Consul integration:

consul {
  address             = "127.0.0.1:8500"
  server_service_name = "nomad"
  client_service_name = "nomad-client"
  auto_advertise      = true
  server_auto_join    = true
  client_auto_join    = true
}

» Custom Address and Port

This example shows pointing the Nomad agent at a different Consul address. Note that you should never point directly at a Consul server; always point to a local client. In this example, the Consul server is bound and listening on the node's private IP address instead of localhost, so we use that:

consul {
  address = "10.0.2.4:8500"
}

» Custom SSL

This example shows configuring custom SSL certificates to communicate with the Consul agent. The Consul agent should be configured to accept certificates similarly, but that is not discussed here:

consul {
  ssl       = true
  ca_file   = "/var/ssl/bundle/ca.bundle"
  cert_file = "/etc/ssl/consul.crt"
  key_file  = "/etc/ssl/consul.key"
}