Bootstrap configuration parameters for Consul agent configuration files

This page provides reference information for bootstrapping parameters in a Consul agent configuration file.

Bootstrap parameters

autopilot This object allows a number of sub-keys to be set which can configure operator-friendly settings for Consul servers. When these keys are provided as configuration, they will only be respected on bootstrapping. If they are not provided, the defaults will be used. In order to change the value of these options after bootstrapping, you will need to use the Consul Operator Autopilot command. For more information about Autopilot, review the Autopilot tutorial.
The following sub-keys are available:
- cleanup_dead_servers - This controls the automatic removal of dead server nodes periodically and whenever a new server is added to the cluster. Defaults to true.
- last_contact_threshold - Controls the maximum amount of time a server can go without contact from the leader before being considered unhealthy. Must be a duration value such as 10s. Defaults to 200ms.
- max_trailing_logs - Controls the maximum number of log entries that a server can trail the leader by before being considered unhealthy. Defaults to 250.
- min_quorum - Sets the minimum number of servers necessary in a cluster. Autopilot will stop pruning dead servers when this minimum is reached. There is no default.
- server_stabilization_time - Controls the minimum amount of time a server must be stable in the 'healthy' state before being added to the cluster. Only takes effect if all servers are running Raft protocol version 3 or higher. Must be a duration value such as 30s. Defaults to 10s.
- redundancy_zone_tag Enterprise - This controls the node_meta key to use when Autopilot is separating servers into zones for redundancy. Only one server in each zone can be a voting member at one time. If left blank (the default), this feature will be disabled.
- disable_upgrade_migration Enterprise - If set to true, this setting will disable Autopilot's upgrade migration strategy in Consul Enterprise of waiting until enough newer-versioned servers have been added to the cluster before promoting any of them to voters. Defaults to false.
- upgrade_version_tag Enterprise - The node_meta tag to use for version info when performing upgrade migrations. If this is not set, the Consul version will be used.
bootstrap - This parameter controls if a server is in "bootstrap" mode. It is important that no more than one server per datacenter be running in this mode. Technically, a server in bootstrap mode is allowed to self-elect as the Raft leader. It is important that only a single node is in this mode; otherwise, consistency cannot be guaranteed as multiple nodes are able to self-elect. It is not recommended to use this flag after a cluster has been bootstrapped.
bootstrap_expect - This parameter provides the number of expected servers in the datacenter. Either this value should not be provided or the value must agree with other servers in the cluster. When provided, Consul waits until the specified number of servers are available and then bootstraps the cluster. This allows an initial leader to be elected automatically. This parameter requires the agent to be configured for server modes.