migrate Block

The migrate block specifies the group's strategy for migrating allocations from draining nodes. If omitted, a default migration strategy is applied. If specified at the job level, the configuration will apply to all groups within the job. Only service jobs with a count greater than 1 support migrate blocks.

job "docs" {
  migrate {
    max_parallel     = 1
    health_check     = "checks"
    min_healthy_time = "10s"
    healthy_deadline = "5m"
  }
}

When one or more nodes are draining, only max_parallel allocations will be stopped at a time. Node draining will not continue until replacement allocations have been healthy for their min_healthy_time or healthy_deadline is reached.

Note that a node's drain deadline will override the migrate block for allocations on that node. The migrate block is for job authors to define how their services should be migrated, while the node drain deadline is for system operators to put hard limits on how long a drain may take.

See the Workload Migration Guide for details on node draining.

migrate Parameters

• max_parallel (int: 1) - Specifies the number of allocations that can be migrated at the same time. This number must be less than the total count for the group as count - max_parallel will be left running during migrations.

• health_check (string: "checks") - Specifies the mechanism in which allocations health is determined. The potential values are:

  • "checks" - Specifies that the allocation should be considered healthy when all of its tasks are running and their associated checks are healthy, and unhealthy if any of the tasks fail or not all checks become healthy. This is a superset of "task_states" mode.

  • "task_states" - Specifies that the allocation should be considered healthy when all its tasks are running and unhealthy if tasks fail.

• min_healthy_time (string: "10s") - Specifies the minimum time the allocation must be in the healthy state before it is marked as healthy and unblocks further allocations from being migrated. This is specified using a label suffix like "30s" or "15m".

• healthy_deadline (string: "5m") - Specifies the deadline in which the allocation must be marked as healthy after which the allocation is automatically transitioned to unhealthy. This is specified using a label suffix like "2m" or "1h".