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Autopilot

Autopilot enables automated workflows for managing Raft clusters. The current feature set includes 3 main features: Server Stabilization, Dead Server Cleanup and State API.

Server stabilization​

Server stabilization helps to retain the stability of the Raft cluster by safely joining new voting nodes to the cluster. When a new voter node is joined to an existing cluster, autopilot adds it as a non-voter instead, and waits for a pre-configured amount of time to monitor it's health. If the node remains to be healthy for the entire duration of stabilization, then that node will be promoted as a voter. The server stabilization period can be tuned using server_stabilization_time (see below).

Dead server cleanup​

Dead server cleanup automatically removes nodes deemed unhealthy from the Raft cluster, avoiding the manual operator intervention. This feature can be tuned using the cleanup_dead_servers, dead_server_last_contact_threshold, and min_quorum (see below).

State API​

State API provides detailed information about all the nodes in the Raft cluster in a single call. This API can be used for monitoring for cluster health.

Follower health​

Follower node health is determined by 2 factors.

  • Its ability to heartbeat to leader node at regular intervals. Tuned using last_contact_threshold (see below).
  • Its ability to keep up with data replication from the leader node. Tuned using max_trailing_logs (see below).

Default configuration​

By default, Autopilot is enabled in OpenBao, although dead server cleanup is not enabled by default.

Autopilot exposes a configuration API to manage its behavior. Autopilot gets initialized with the following default values. If these default values do not meet your expected autopilot behavior, don't forget to set them to your desired values.

  • cleanup_dead_servers - false

    • This controls whether to remove dead servers from the Raft peer list periodically or when a new server joins. This requires that min-quorum is also set.

  • dead_server_last_contact_threshold - 24h

    • Limit on the amount of time a server can go without leader contact before being considered failed. This takes effect only when cleanup_dead_servers is set.

  • min_quorum - This doesn't default to anything and should be set to the expected number of voters in your cluster when cleanup_dead_servers is set as true.

    • Minimum number of servers that should always be present in a cluster. Autopilot will not prune servers below this number.

  • max_trailing_logs - 1000

    • Amount of entries in the Raft Log that a server can be behind before being considered unhealthy.

  • last_contact_threshold - 10s

    • Limit on the amount of time a server can go without leader contact before being considered unhealthy.

  • server_stabilization_time - 10s

    • Minimum amount of time a server must be in a healthy state before it can become a voter. Until that happens, it will be visible as a peer in the cluster, but as a non-voter, meaning it won't contribute to quorum.
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Note: Autopilot in OpenBao does similar things to what autopilot does in Consul. However, the configuration in these 2 systems differ in terms of default values and thresholds; some additional parameters might also show up in OpenBao in comparison to Consul as well. Autopilot in OpenBao and Consul use different technical underpinnings requiring these differences, to provide the autopilot functionality.