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Revision History

shirleydst
shirleydst Posts: 11
in LFD259 Class Forum

In Exercise 5.4: Rolling Updates and Rollbacks, step 12 states:
In our case there are only two revisions, which is also the default number kept.

How can we override this?

Searching on "Revision History" I found
Revision History Limit - A Deployment's revision history is stored in the ReplicaSets it controls.
.spec.revisionHistoryLimit is an optional field that specifies the number of old ReplicaSets to retain to allow rollback. **
try1 has:
**revisionHistoryLimit: 10

Yet after experimenting with --record to create additional revisions, it seems that only two are kept:
$ k rollout history deployment try1
deployment.apps/try1
REVISION CHANGE-CAUSE
3
4 kubectl edit deployments.apps try1 --record=true
$ k rollout history deployment try1 --revision=1
error: unable to find the specified revision
$ k rollout history deployment try1 --revision=3
deployment.apps/try1 with revision #3
Pod Template: ....

There is an example on https://kubernetes.io/docs/concepts/workloads/controllers/deployment/#revision-history-limit which shows 3 items of revision history.

Comments

  • shirleydst
    shirleydst Posts: 11

    Interestingly this seemed to behave differently when I worked on something else. However it still didn't behave in a consistent way.

  • chrispokorni
    chrispokorni Posts: 2,015

    Hi @shirleydst,

    Did you happen to run several consecutive rolling updates? How many of them generated revisions in the history list?

    Regards,
    -Chris

  • shirleydst
    shirleydst Posts: 11

    I made 4 edits to the deployment's image version and although the revision history index incremented, only two items of history were listed at any point in time.

  • serewicz
    serewicz Posts: 1,000

    Hello,

    Things change all the time with Kubernetes. There was a release where there were two changes kept, and now I think it's back up to 10. The current setting is revisionHistoryLimit: 10 Which can be edited or set when the deployment is created.

    When you use a previous rollout of a deployment the replicaset numbering is changed. So where you may have had a "2" it gets renumbered to "6" should you go back to it after making changes 3,4, and 5. Using a tool like Helm, Spinnaker, or other release tool would provide a durable and long-term way to manage changes made to a deployment.

    Regards,

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