CODEWITHSUNDEEP
kubernetes
yesman
yesman

Reputation: 7838

Can I see a rollout in more detail?

I was doing a practice exam on the website killer.sh , and ran into a question I feel I did a hacky solution to. Given a deployment that has had a bad rollout, revert to the last revision that didn't have any issues. If I check a deployment's rollout history, for example with the command:

kubectl rollout history deployment mydep

I get a small table with version numbers, and "change-cause" commands. Is there any way to check the changes made to the deployment's yaml file for a specific revision? Because I was stumped in figuring out which specific revision didn't have the error inside of it.

Upvotes: 1

Views: 2861

Answers (4)

Saintali
Saintali

Reputation: 4571

You can also get some additional details by passing the --revision flag:

kubectl rollout history deployment mydep --revision=26

Or even diff two such revisions in bash:

diff <(kubectl rollout history deployment mydep --revision=26) \
     <(kubectl rollout history deployment mydep --revision=25)

Upvotes: 2

Rohit
Rohit

Reputation: 1301

You can record the last executed command that changed the deployment with --record option. When using --record you would see the last executed command executed(change-cause) to the deployment metadata.annotations. You will not see this in your local yaml file but when you try to export the deployment as yaml then you will notice the change.

--record option like below

kubectl create deployment <deployment name> --image=<someimage> > testdelpoyment.yaml

kubectl create -f testdeployment.yaml --record

or

kubectl set image deployment/<deploymentname> imagename=newimagename:newversion --record

Upvotes: 1

Arghya Sadhu
Arghya Sadhu

Reputation: 44637

Kubernetes does not store more than what is necessary for it to operate and most of the time that is just the desired state because kubernetes is not a version control system.

This is preciously why you need to have a version control system coupled with tools like helm or kustomize where you store the deployment yamls and apply them to the cluster with a new version of the software. This helps in going back in history to dig out details when things break.

Upvotes: 2

BogdanL
BogdanL

Reputation: 691

Behind the scenes a Deployment creates a ReplicaSet that has its metadata.generation set to the REVISION you see in kubectl rollout history deployment mydep, so you can look at and diff old ReplicaSets associated with the Deployment.

On the other hand, being an eventually-consistent system, kubernetes has no notion of "good" or "bad" state, so it can't know what was the last successful deployment, for example; that's why deployment tools like helm, kapp etc. exist.

Upvotes: 3

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