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Consul Maint

Command: consul maint

Corresponding HTTP API Endpoint: [PUT] /v1/agent/maintenance

The maint command provides control of service maintenance mode. Using the command, it is possible to mark a service provided by a node or all the services on the node as a whole as "under maintenance". In this mode of operation, the service will not appear in DNS query results, or API results. This effectively takes the service out of the pool of available "healthy" nodes of a service.

Under the hood, maintenance mode is activated by registering a health check in critical status against a service, and deactivated by deregistering the health check.

The table below shows this command's required ACLs. Configuration of blocking queries and agent caching are not supported from commands, but may be from the corresponding HTTP endpoint.

ACL Required
node:write

Usage

Usage: consul maint [options]

Command Options

  • -enable - Enable node-wide maintenance mode flag. If combined with the -service flag, we operate on a specific service ID instead. Node and service maintenance flags are independent.

  • -disable - Disable the node-wide maintenance flag. If combined with the -service flag, we operate on a specific service ID instead. Node and service maintenance flags are independent.

  • -reason - An optional reason for placing the service into maintenance mode. If provided, this reason will be visible in the newly- registered critical check's "Notes" field.

  • -service - An optional service ID to control maintenance mode for a given service. By providing this flag, the -enable and -disable flags functionality is modified to operate on the given service ID.

API Options

  • -ca-file=<value> - Path to a CA file to use for TLS when communicating with Consul. This can also be specified via the CONSUL_CACERT environment variable.

  • -ca-path=<value> - Path to a directory of CA certificates to use for TLS when communicating with Consul. This can also be specified via the CONSUL_CAPATH environment variable.

  • -client-cert=<value> - Path to a client cert file to use for TLS when verify_incoming is enabled. This can also be specified via the CONSUL_CLIENT_CERT environment variable.

  • -client-key=<value> - Path to a client key file to use for TLS when verify_incoming is enabled. This can also be specified via the CONSUL_CLIENT_KEY environment variable.

  • -http-addr=<addr> - Address of the Consul agent with the port. This can be an IP address or DNS address, but it must include the port. This can also be specified via the CONSUL_HTTP_ADDR environment variable. In Consul 0.8 and later, the default value is http://127.0.0.1:8500, and https can optionally be used instead. The scheme can also be set to HTTPS by setting the environment variable CONSUL_HTTP_SSL=true. This may be a unix domain socket using unix:///path/to/socket if the agent is configured to listen that way.

  • -tls-server-name=<value> - The server name to use as the SNI host when connecting via TLS. This can also be specified via the CONSUL_TLS_SERVER_NAME environment variable.

  • -token=<value> - ACL token to use in the request. This can also be specified via the CONSUL_HTTP_TOKEN environment variable. If unspecified, the query will default to the token of the Consul agent at the HTTP address.

  • -token-file=<value> - File containing the ACL token to use in the request instead of one specified via the -token argument or CONSUL_HTTP_TOKEN environment variable. This can also be specified via the CONSUL_HTTP_TOKEN_FILE environment variable.

List mode

If neither -enable nor -disable are passed, the maint command will switch to "list mode", displaying any current maintenances. This may return blank if nothing is currently under maintenance. The output will look like:

$ consul maint
Node:
  Name:   node1.local
  Reason: This node is broken.

Service:
  ID:     redis
  Reason: Redis is currently offline.
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