📖 Add implementation notes to the in-place update proposal #12880
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| # In-place updates in Cluster API - Implementations notes | |||
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| This document is an collection of notes about implementation details for the in-place update proposal. | |||
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| This document is an collection of notes about implementation details for the in-place update proposal. | |
| This document is a collection of notes about implementation details for the in-place update proposal. |
| MS Controller->>M1: Move M1 to MS2 (NewMS)<br/>Apply annotation ".../pending-acknowledge-move": ""<br/>Apply annotation ".../update-in-progress": "" | ||
| ``` | ||
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| Workflow #3: MD controller recongnizes the newMS being moved to the newMS and it scales up newMS to acknowledge the operation |
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| Workflow #3: MD controller recongnizes the newMS being moved to the newMS and it scales up newMS to acknowledge the operation | |
| Workflow #3: MD controller recognizes that a Machine has been moved to the new MachineSet and scales up the new MachineSet to acknowledge the operation. | |
| autonumber | ||
| participant MS Controller as MS Controller<br/>when reconciling<br/>MS2 (NewMS) | ||
| participant MS2 (NewMS) | ||
| participant M1 as M1<br/>now controller by<br/>MS2 (NewMS) |
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| participant M1 as M1<br/>now controller by<br/>MS2 (NewMS) | |
| participant M1 as M1<br/>now controlled by<br/>MS2 (NewMS) |
| MD Controller->>MS2 (NewMS): Scale up to acknowledge M1<br/>Apply annotation ".../acknowledged-move": "M1" | ||
| ``` | ||
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| Workflow #4: MS controller, when reconciling newMS, detects a machine has been acknoledged; it cleanups annotation on the machine and this unblocks the in-place upgrade to start |
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| Workflow #4: MS controller, when reconciling newMS, detects a machine has been acknoledged; it cleanups annotation on the machine and this unblocks the in-place upgrade to start | |
| Workflow #4: MS controller, when reconciling newMS, detects that a machine has been acknowledged; it cleans up annotations on the machine, allowing the in-place upgrade to begin. | |
| participant M1 as M1<br/>now controlled by<br/>MS2 (NewMS) | ||
| MD Controller-->>M1: Are you pending acknowledge? | ||
| M1-->>MD Controller: Yes! | ||
| MD Controller->>MS2 (NewMS): Scale up to acknowledge M1<br/>Apply annotation ".../acknowledged-move": "M1" |
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| MD Controller->>MS2 (NewMS): Scale up to acknowledge M1<br/>Apply annotation ".../acknowledged-move": "M1" | |
| MD Controller->>MS2 (NewMS): Scale up to acknowledge receipt of M1<br/>Apply annotation ".../acknowledged-move": "M1" |
| - MS controller, when reconciling the newMS, will take over the moved machine and start the actual in-place upgrade operation | ||
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| - Orchestration of in-place upgrades between MD controller, MS controller, and Machine controller is implemented using annotations. | ||
| Following schemas provide a overview of how new annotation are used |
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| Following schemas provide a overview of how new annotation are used | |
| Following schemas provide an overview of how new annotations are used. |
| - Old MS will be informed to move machines to the newMS, and newMS will be informed it will receive machines from oldMS. | ||
| - MS controller manages a subset of Machines | ||
| - When scaling down the old MS, if required to move, MS controller is responsible for moving a Machine to newMS | ||
| - MS controller, when reconciling the newMS, will take over the moved machine and start the actual in-place upgrade operation |
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| - MS controller, when reconciling the newMS, will take over the moved machine and start the actual in-place upgrade operation | |
| - When reconciling the new MachineSet, the MS controller takes ownership of the moved machine and begins the actual in-place upgrade. |
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| - The implementation respects the existing set of responsibilities of each controller | ||
| - MD controller manages MS | ||
| - MD controller enforces maxUnavailable, maxSurge | ||
| - MD controller decides when to scale up newMS, when to scale down oldMS | ||
| - When there is a decision to scale down, MD controller should check if this can be done via in-place vs delete/recreate. If in-place is possible: | ||
| - Old MS will be informed to move machines to the newMS, and newMS will be informed it will receive machines from oldMS. |
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| - The implementation respects the existing set of responsibilities of each controller | |
| - MD controller manages MS | |
| - MD controller enforces maxUnavailable, maxSurge | |
| - MD controller decides when to scale up newMS, when to scale down oldMS | |
| - When there is a decision to scale down, MD controller should check if this can be done via in-place vs delete/recreate. If in-place is possible: | |
| - Old MS will be informed to move machines to the newMS, and newMS will be informed it will receive machines from oldMS. | |
| - The implementation respects the existing set of responsibilities of each controller: | |
| - MD controller manages MS: | |
| - MD controller enforces maxUnavailable, maxSurge | |
| - MD controller decides when to scale up newMS, when to scale down oldMS | |
| - When scaling down, the MD controller checks whether the operation can be performed in-place instead of delete/recreate. If in-place is possible: | |
| - Old MS is instructed to move machines to the newMS, and newMS is informed to receive machines from oldMS. |
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| - In place is always considered as potentially disruptive | ||
| - in place must respect maxUnavailable | ||
| - if maxUnavailable is zero, a new machine must be created, then as soon as there is “buffer” for in-place, in-place update is done |
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| - if maxUnavailable is zero, a new machine must be created, then as soon as there is “buffer” for in-place, in-place update is done | |
| - if maxUnavailable is zero, a new machine must be created first, then as soon as there is a “buffer” for in-place, the in-place update can proceed. |
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| - if maxUnavailable is zero, a new machine must be created, then as soon as there is “buffer” for in-place, in-place update is done | |
| - if maxUnavailable is zero, a new machine must be created, then as soon as there is “buffer” for in-place, in-place update can proceed |
Just to avoid interpretation of "done" as "finished".
| This document is an collection of notes about implementation details for the in-place update proposal. | ||
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| As soon as the implementation will be completed, some of the notes in this document will be moved back | ||
| into the proposal or moved to the user facing documentation about this feature. |
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| into the proposal or moved to the user facing documentation about this feature. | |
| into the proposal or into the user-facing documentation for this feature. |
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Unknown CLA label state. Rechecking for CLA labels. Send feedback to sig-contributor-experience at kubernetes/community. /check-cla |
k8s-ci-robot
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fabriziopandini
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@lentzi90 @furkatgofurov7 thanks for feedback, everything should be addressed now |
k8s-ci-robot
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LGTM label has been added. Git tree hash: 72a05da489f4d135173f986fa6ad8a30c72a2f97
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/assign |
sbueringer
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Oct 28, 2025
| participant RX | ||
| participant MS1 (OldMS) | ||
| participant MS2 (NewMS) | ||
| MD Controller-->>+RX: Can you update in-place from MS1 (OldMS) to MD2 (NewMS)? |
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| MD Controller-->>+RX: Can you update in-place from MS1 (OldMS) to MD2 (NewMS)? | |
| MD Controller-->>+RX: Can you update in-place from MS1 (OldMS) to MS2 (NewMS)? |
| participant MS Controller as MS Controller<br/>when reconciling<br/>MS1 (OldMS) | ||
| participant MS1 (OldMS) | ||
| participant MS2 (NewMS) | ||
| participant M1 as M1<br/>controlled by<br/>MS1 (OldMS),<br/>selected to be moved to MS2 |
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| participant M1 as M1<br/>controlled by<br/>MS1 (OldMS),<br/>selected to be moved to MS2 | |
| participant M1 as M1<br/>controlled by<br/>MS1 (OldMS),<br/>selected to be moved to MS2 (NewMS) |
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Thx! /lgtm |
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LGTM label has been added. Git tree hash: 912e9ef1456764b16e97aca8738a85e0a1f80af6
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[APPROVALNOTIFIER] This PR is APPROVED This pull-request has been approved by: sbueringer The full list of commands accepted by this bot can be found here. The pull request process is described here
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What this PR does / why we need it:
Start collecting some notes about the ongoing work for in-place
Which issue(s) this PR fixes:
Fixes #
Part of #12291
/area documentation