kubectl-realname-diff

Kubectl Real Name Diff

A kubectl plugin that diffs live and local resources ignoring Kustomize hash-suffixes.

What's this ?

kubectl realname-diff works the same as kubectl diff, but if you set "real name" as a label, local and live resources with the same label will be compared.

This is especially beneficial if you use the Kustomize and enable hash suffixing ConfigMap/Secret names. In case of kubectl diff, local and live resources with hash suffixed name are considered as irrelevant. So you will not be able to get any results comparing them.

With realname-diff, you can compare the resources with hash suffixed name by specifying the comparison target with "real name" labels.

Usage

First, you have set the label realname-diff/realname: [real name] to the resources you want to diff ignoring difference of {.metadata.name}.

In Kustomize, you can set the label in ConfigMap/Secret Generator fields.

resources:
  # resources that have references to the ConfigMap "nginx-conf"
  - deployment.yaml

configMapGenerator:
  - name: nginx-conf
    files:
      - conf/nginx.conf
    options:
      labels:
        realname-diff/realname: nginx-conf
      # hash suffix is enabled by default

Then, apply the manifests to your kubernetes cluster.

# assume you have placed the kustomization.yaml in "./example" directory
$ kustomize build ./example | kubectl apply -f -

# you can get the ConfigMap with hash suffixed name.
$ kubectl get configmap --show-labels
NAME                    DATA   AGE   LABELS
nginx-conf-m5d2cggb7k   1      18s   realname-diff/realname=nginx-conf

Next, edit the content you want to pack into ConfigMap and use kubectl realname-diff to diff the local ConfigMap and the live one.

$ echo "# test" >> ./example/conf/nginx.conf

$ kustomize build ./example | kubectl realname-diff -f -

You can see the diff result comparing contents in the ConfigMap. The local ConfigMap is not treated as new one.

diff -u -N /var/folders/2n/lgqgy6f151l5mw1x4dj_7ztw0000gn/T/LIVE-116798495/apps.v1.Deployment.default.nginx /var/folders/2n/lgqgy6f151l5mw1x4dj_7ztw0000gn/T/MERGED-2431241138/apps.v1.Deployment.default.nginx
--- /var/folders/2n/lgqgy6f151l5mw1x4dj_7ztw0000gn/T/LIVE-116798495/apps.v1.Deployment.default.nginx	2021-12-24 00:04:23.000000000 +0900
+++ /var/folders/2n/lgqgy6f151l5mw1x4dj_7ztw0000gn/T/MERGED-2431241138/apps.v1.Deployment.default.nginx	2021-12-24 00:04:23.000000000 +0900
@@ -6,7 +6,7 @@
     kubectl.kubernetes.io/last-applied-configuration: |
       {"apiVersion":"apps/v1","kind":"Deployment","metadata":{"annotations":{},"labels":{"app":"nginx","prunable":"true"},"name":"nginx","namespace":"default"},"spec":{"replicas":2,"selector":{"matchLabels":{"app":"nginx","prunable":"true"}},"template":{"metadata":{"labels":{"app":"nginx","prunable":"true"}},"spec":{"containers":[{"image":"nginx:latest","name":"nginx","ports":[{"containerPort":80}],"volumeMounts":[{"mountPath":"/etc/nginx/htpasswd","name":"htpasswd","readOnly":true},{"mountPath":"/etc/nginx","name":"nginx-conf","readOnly":true}]}],"volumes":[{"name":"htpasswd","secret":{"secretName":"htpasswd-k7mbh9mm68"}},{"configMap":{"name":"nginx-conf-m5d2cggb7k"},"name":"nginx-conf"}]}}}}
   creationTimestamp: "2021-12-23T15:00:12Z"
-  generation: 1
+  generation: 2
   labels:
     app: nginx
     prunable: "true"
@@ -177,7 +177,7 @@
           secretName: htpasswd-k7mbh9mm68
       - configMap:
           defaultMode: 420
-          name: nginx-conf-m5d2cggb7k
+          name: nginx-conf-b6gmtkgcd5
         name: nginx-conf
 status:
   availableReplicas: 2
diff -u -N /var/folders/2n/lgqgy6f151l5mw1x4dj_7ztw0000gn/T/LIVE-116798495/v1.ConfigMap.default.nginx-conf-m5d2cggb7k /var/folders/2n/lgqgy6f151l5mw1x4dj_7ztw0000gn/T/MERGED-2431241138/v1.ConfigMap.default.nginx-conf-m5d2cggb7k
--- /var/folders/2n/lgqgy6f151l5mw1x4dj_7ztw0000gn/T/LIVE-116798495/v1.ConfigMap.default.nginx-conf-m5d2cggb7k	2021-12-24 00:04:23.000000000 +0900
+++ /var/folders/2n/lgqgy6f151l5mw1x4dj_7ztw0000gn/T/MERGED-2431241138/v1.ConfigMap.default.nginx-conf-m5d2cggb7k	2021-12-24 00:04:23.000000000 +0900
@@ -16,12 +16,10 @@
             }
         }
     }
+    # test
 kind: ConfigMap
 metadata:
   ...(snip last-applied-configuration label)..
   labels:
     prunable: "true"
     realname-diff/realname: nginx-conf
@@ -33,17 +31,13 @@
     manager: kubectl-client-side-apply
     operation: Update
-    time: "2021-12-23T15:00:12Z"
-  name: nginx-conf-m5d2cggb7k
+    time: "2021-12-23T15:04:23Z"
+  name: nginx-conf-b6gmtkgcd5
   namespace: default
-  resourceVersion: "82594"
-  uid: 6a5d347c-d936-49c6-825b-70e2e39eb676
+  uid: 0d69cf40-d201-47fe-bad2-8c3333ef0d07

For a complete example, see the example directory.

Installation

by go install

Use go install as follows:

$ go install github.com/hhiroshell/kubectl-realname-diff/cmd/kubectl-realname_diff@latest

as a kubectl plugin

Make sure the krew is already installed.

Then install it via the krew as follows:

$ kubectl krew install realname-diff

License

Kubectl Real Name Diff is licensed under the Apache License 2.0, and includes works distributed under same one.