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Before a migrate is carried out, we wish to check that the current state of the instance is ready for migration with a pre-check - effectively like a healthcheck.

Only once this done should we be able to trigger migrate.

Assumptions:

  • We assume that composition target is already primed
  • Participants execute the effective pre-check.
  • Pre-check is completely optional. it will be executed before the migration. If it fail or the migration is not supported, can the migration be executed?
  • User receives the result of the precheck on the outProperties result.

Solution: create a new flow for migration-precheck

User can send the action migration-precheck POST. The user can do the action migration POST after that. The migration flow will be unchanged and backwards-compatible.

  • User send migration-precheck action
  • Acm-runtime set the state of the instance in "MIGRATING-PRECHECK"
  • Acm-runtime sends migration-precheck message to participants (it will be AUTOMATION_COMPOSITION_MIGRATION message with Boolean flag "precheck" set to true)
  • Participant receives migration-precheck message and executes the precheck and sends the result (it will be a new method "migratePrecheck()" that participant has to implement)
  • Acm-runtime receives precheck-result messages from all participants
  • Acm-runtime shows this result into the stateChangeResult
    • NO_ERROR: means the migration is supported (state will back as before the precheck-migration call)
    • FAILED: means something went wrong during the migration precheck (state will be in "MIGRATING-PRECHECK")
  • It will be implemented migratePrecheck() in participant-simulator to test all scenarios.


Allowed operations

stateChangeResultstate

Allowed
Operation

Not Allowed
Operation
FAILEDMIGRATING-PRECHECKUNDEPLOY, MIGRATE_PRECHECKUPDATE, DELETE, DEPLOY, MIGRATE, UNLOCK, LOCK
TIMEOUTMIGRATING-PRECHECKUNDEPLOY, MIGRATE_PRECHECKUPDATE, DELETE, DEPLOY, MIGRATE, UNLOCK, LOCK

How the user can send the action migration-precheck POST?

Below the list of solutions:

  • parameter in POST action: {{address}}:{{port}}/onap/policy/clamp/acm/v2/compositions/{{compositionId}}/instances?precheck=true
  • new filed into the Body:
name: DemoInstance0
version: 1.0.1
compositionId: {{composition1Id}}
instanceId: {{instanceId}}
compositionTargetId: {{composition2Id}}
precheck: true
.......................

What state suits for migration-precheck?

Differently in what happen in deploy, undeploy, update and migrate, the migration-precheck operation do not make changes in the applications (same will be for prepare and review). What state is most suitable for that operation?
Using deployState, lockState or a new checkState does not impact the migration-precheck functionality, it is an implementation detail that it help to understand how to implement all new functionalities.


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