» Nomad Configuration

Nomad agents have a variety of parameters that can be specified via configuration files or command-line flags. Configuration files are written in HCL. Nomad can read and combine parameters from multiple configuration files or directories to configure the Nomad agent.

» Load Order and Merging

The Nomad agent supports multiple configuration files, which can be provided using the -config CLI flag. The flag can accept either a file or folder:

$ nomad agent -config=server.conf -config=/etc/nomad -config=extra.json

This will load configuration from server.conf, from .hcl and .json files under /etc/nomad, and finally from extra.json. Files are loaded and merged in lexicographical order. Directories are not loaded recursively.

As each file is processed, its contents are merged into the existing configuration. When merging, any non-empty values from the latest config file will append or replace parameters in the current configuration. An empty value means "" for strings, 0 for integer or float values, and false for booleans. Since empty values are ignored you cannot disable an parameter like server mode once you've enabled it.

Here is an example Nomad agent configuration that runs in both client and server mode.

data_dir  = "/var/lib/nomad"

bind_addr = "0.0.0.0" # the default

advertise {
  # Defaults to the first private IP address.
  http = "1.2.3.4"
  rpc  = "1.2.3.4"
  serf = "1.2.3.4:5648" # non-default ports may be specified
}

server {
  enabled          = true
  bootstrap_expect = 3
}

client {
  enabled       = true
  network_speed = 10
  options {
    "driver.raw_exec.enable" = "1"
  }
}

consul {
  address = "1.2.3.4:8500"
}

» General Parameters

  • acl (ACL: nil) - Specifies configuration which is specific to ACLs.

  • addresses (Addresses: see below) - Specifies the bind address for individual network services. Any values configured in this stanza take precedence over the default bind_addr. The values support go-sockaddr/template format.

    • http - The address the HTTP server is bound to. This is the most common bind address to change.
    • rpc - The address to bind the internal RPC interfaces to. Should be exposed only to other cluster members if possible.
    • serf - The address used to bind the gossip layer to. Both a TCP and UDP listener will be exposed on this address. Should be exposed only to other cluster members if possible.
  • advertise (Advertise: see below) - Specifies the advertise address for individual network services. This can be used to advertise a different address to the peers of a server or a client node to support more complex network configurations such as NAT. This configuration is optional, and defaults to the bind address of the specific network service if it is not provided. Any values configured in this stanza take precedence over the default bind_addr.

    If the bind address is 0.0.0.0 then the address private IP found is advertised. You may advertise an alternate port as well. The values support go-sockaddr/template format.

    • http - The address to advertise for the HTTP interface. This should be reachable by all the nodes from which end users are going to use the Nomad CLI tools.
    • rpc - The address advertised to Nomad client nodes. This allows advertising a different RPC address than is used by Nomad Servers such that the clients can connect to the Nomad servers if they are behind a NAT.
    • serf - The address advertised for the gossip layer. This address must be reachable from all server nodes. It is not required that clients can reach this address. Nomad servers will communicate to each other over RPC using the advertised Serf IP and advertised RPC Port.
  • bind_addr (string: "0.0.0.0") - Specifies which address the Nomad agent should bind to for network services, including the HTTP interface as well as the internal gossip protocol and RPC mechanism. This should be specified in IP format, and can be used to easily bind all network services to the same address. It is also possible to bind the individual services to different addresses using the addresses configuration option. Dev mode (-dev) defaults to localhost. The value supports go-sockaddr/template format.

  • client (Client: nil) - Specifies configuration which is specific to the Nomad client.

  • consul (Consul: nil) - Specifies configuration for connecting to Consul.

  • datacenter (string: "dc1") - Specifies the data center of the local agent. All members of a datacenter should share a local LAN connection.

  • data_dir (string: required) - Specifies a local directory used to store agent state. Client nodes use this directory by default to store temporary allocation data as well as cluster information. Server nodes use this directory to store cluster state, including the replicated log and snapshot data. This must be specified as an absolute path.

  • disable_anonymous_signature (bool: false) - Specifies if Nomad should provide an anonymous signature for de-duplication with the update check.

  • disable_update_check (bool: false) - Specifies if Nomad should not check for updates and security bulletins.

  • enable_debug (bool: false) - Specifies if the debugging HTTP endpoints should be enabled. These endpoints can be used with profiling tools to dump diagnostic information about Nomad's internals.

  • enable_syslog (bool: false) - Specifies if the agent should log to syslog. This option only works on Unix based systems.

  • http_api_response_headers (map<string|string>: nil) - Specifies user-defined headers to add to the HTTP API responses.

  • leave_on_interrupt (bool: false) - Specifies if the agent should gracefully leave when receiving the interrupt signal. By default, the agent will exit forcefully on any signal. This value should only be set to true on server agents if it is expected that a terminated server instance will never join the cluster again.

  • leave_on_terminate (bool: false) - Specifies if the agent should gracefully leave when receiving the terminate signal. By default, the agent will exit forcefully on any signal. This value should only be set to true on server agents if it is expected that a terminated server instance will never join the cluster again.

  • log_level (string: "INFO") - Specifies the verbosity of logs the Nomad agent will output. Valid log levels include WARN, INFO, or DEBUG in increasing order of verbosity.

  • name (string: [hostname]) - Specifies the name of the local node. This value is used to identify individual agents. When specified on a server, the name must be unique within the region.

  • ports (Port: see below) - Specifies the network ports used for different services required by the Nomad agent.

    • http - The port used to run the HTTP server.
    • rpc - The port used for internal RPC communication between agents and servers, and for inter-server traffic for the consensus algorithm (raft).
    • serf - The port used for the gossip protocol for cluster membership. Both TCP and UDP should be routable between the server nodes on this port.

    The default values are:

    ports {
      http = 4646
      rpc  = 4647
      serf = 4648
    }
    
  • region (string: "global") - Specifies the region the Nomad agent is a member of. A region typically maps to a geographic region, for example us, with potentially multiple zones, which map to datacenters such as us-west and us-east.

  • sentinel (Sentinel: nil) - Specifies configuration for Sentinel policies.

  • server (Server: nil) - Specifies configuration which is specific to the Nomad server.

  • syslog_facility (string: "LOCAL0") - Specifies the syslog facility to write to. This has no effect unless enable_syslog is true.

  • tls (TLS: nil) - Specifies configuration for TLS.

  • vault (Vault: nil) - Specifies configuration for connecting to Vault.

» Examples

» Custom Region and Datacenter

This example shows configuring a custom region and data center for the Nomad agent:

region     = "europe"
datacenter = "ams"

» Enable CORS

This example shows how to enable CORS on the HTTP API endpoints:

http_api_response_headers {
  "Access-Control-Allow-Origin" = "*"
}