sled agent: add facility to set/clear instances' migration IDs #2862
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smklein
approved these changes
Apr 19, 2023
Add a sled agent API that allows Nexus to set or clear the migration ID and destination Propolis ID in an instance's runtime state. This advances the instance's Propolis generation number. Sled agent requires callers to furnish the instance runtime state they intend to transition from. This lets Nexus use this API and an instance's migration ID field to arbitrate between multiple concurrent migration attempts: if an instance is running with Propolis generation X, and two (or more) migration sagas observe that generation, then only one will successfully set migration IDs and be allowed to continue migration. Subsequent commits will update the migration saga to use this API.
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Going to go ahead and merge this one so that the changes to the migration saga proper can go up for review. |
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This is PR no. 6 in the live migration series. The work in this PR will be used in the next PR in this sequence.
Add a sled agent API that allows Nexus to set or clear the migration ID and destination Propolis ID in an instance's runtime state. This advances the instance's Propolis generation number.
Sled agent requires callers to furnish the instance runtime state they intend to transition from. This lets Nexus use this API and an instance's migration ID field to arbitrate between multiple concurrent migration attempts: if an instance is running with Propolis generation X, and two (or more) migration sagas observe that generation, then only one will successfully set migration IDs and be allowed to continue migration.
Subsequent commits will update the migration saga to use this API.