kubectl-history

kubectl-history

🚀 Time-travel through your cluster 🕰️

About

kubectl-history is a kubectl plugin and can be invoked as kubectl history, or for short k history.

The history plugin allows you to go back in time in the history of rollouts and answers common questions like "Why was my Deployment rolled?"

It gives more output than kubectl rollout history and is easier to use than kubectl get replicaset or kubectl get controllerrevision.

Installation

go install github.com/timebertt/kubectl-history@latest

Usage

k history get / k history list

Get the rollout history of a workload resource (Deployment, StatefulSet, or DaemonSet).

The history is based on the ReplicaSets/ControllerRevisions still in the system. I.e., the history is limited by the configured revisionHistoryLimit.

By default, all revisions are printed as a list. If the --revision flag is given, the selected revision is printed instead.

$ k history get deploy nginx -owide
NAME               REVISION   AGE   CONTAINERS   IMAGES
nginx-77b4fdf86c   1          22m   nginx        nginx
nginx-7bf8c77b5b   2          21m   nginx        nginx:latest
nginx-7bb88f5ff4   3          20m   nginx        nginx:1.24

$ k history get deploy nginx -r -1 -oyaml
apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: nginx-7bb88f5ff4
...

This is similar to using k get replicaset or k get controllerrevision, but allows easy selection of the relevant objects and returns a sorted list. This is also similar to k rollout history, but doesn't only print revision numbers.

k history diff / k history why

Compare multiple revisions of a workload resource (Deployment, StatefulSet, or DaemonSet). A.k.a., "Why was my Deployment rolled?"

The history is based on the ReplicaSets/ControllerRevisions still in the system. I.e., the history is limited by the configured revisionHistoryLimit.

By default, the latest two revisions are compared. The --revision flag allows selecting the revisions to compare.

$ k history diff deploy nginx
comparing revisions 2 and 3 of deployment.apps/nginx
--- /var/folders/d8/x7ty7dh12sg7vrq374x52pk80000gq/T/deployment.apps_nginx-2577026088/2-nginx-7bf8c77b5b.yaml	2024-05-22 23:16:51
+++ /var/folders/d8/x7ty7dh12sg7vrq374x52pk80000gq/T/deployment.apps_nginx-2577026088/3-nginx-7bb88f5ff4.yaml	2024-05-22 23:16:51
@@ -7,7 +7,7 @@
     app: nginx
 spec:
   containers:
-  - image: nginx:latest
+  - image: nginx:1.24
     imagePullPolicy: Always
     name: nginx
     resources: {}

The k history diff command uses diff -u -N to compare revisions by default. It also respects the KUBECTL_EXTERNAL_DIFF environment variable like the kubectl diff command. To get a nicer diff view, you can use one of these:

# Add color to the diff output
k history diff deploy nginx | colordiff
# Specify an external diff programm
KUBECTL_EXTERNAL_DIFF="colordiff -u" k history diff deploy nginx
# Show diff in VS Code
KUBECTL_EXTERNAL_DIFF="code --diff --wait" k history diff deploy nginx