Container changes in`Deployment` => "element [0] missing"

Using this deployment.yaml:

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: nginx
  namespace: test
spec:
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx
          ports:
            - containerPort: 80
              name: http
              protocol: TCP

If I change a field in the containers part, e.g. the containerPort, kubediff returns:

## test/nginx (Deployment)

.spec.template.spec.containers: 'element [0]' missing

[carlosdagos]

Getting the same issue. An update would be awesome. Thanks for kubediff!

[damienleger]

I’ve coded a workaround for this. It’s far from perfect because tests are broken and all but that fits my needs. Looks interesting to share anyway.

My understanding is that after the change https://github.com/weaveworks/kubediff/pull/31 every change in any deep after a list results in ‘element[X] missing’ issue we are talking about. Hence if you change the image of a container (the most likely on a daily change), you have this issue, making the tool quite useless imho. The change make sense in a way that if you remove or add element in a list from running or wished configuration, differences between elements get mixed up and you end up with an horrible diff output e.g.: you remove wished var1 then running var1 is diffed with wished var2, running var2 is diffed with wished var3 and so on… Luckily changes not happening much except for environment variable list.

I then did the following change. Reverted the old behavior for list having same size, and if not return ‘element missing’ except for .spec.template.spec.containers[X].env whish have a special treat.

Let’s say you running on this

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: nginx
  namespace: test
spec:
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx:1.14.1
          ports:
            - containerPort: 80
              name: http
              protocol: TCP
          env:
            - name: name1
              value: value1
            - name: name2
              value: value2
            - name: name3
              value: value3

and want this:

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: nginx
  namespace: test
spec:
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx:1.14.2
          ports:
            - containerPort: 80
              name: http
              protocol: TCP
          env:
            - name: name1
              value: value1.1
            - name: name4
              value: value4

With my hack, kubediff output is:

## test/nginx (Deployment.v1beta1.extensions)

.spec.template.spec.containers[0].image: 'nginx:1.14.2' != 'nginx:1.14.1'
## test/nginx (Deployment.v1beta1.extensions)

.spec.template.spec.containers[0].env: Unequal lengths: 2 != 3
## test/nginx (Deployment.v1beta1.extensions)

.spec.template.spec.containers[0].env: Diff: name4 in wished config only
## test/nginx (Deployment.v1beta1.extensions)

.spec.template.spec.containers[0].env: Diff: name2 in running config only
## test/nginx (Deployment.v1beta1.extensions)

.spec.template.spec.containers[0].env: Diff: name3 in running config only
## test/nginx (Deployment.v1beta1.extensions)

.spec.template.spec.containers[0].env[0].value: 'value1.1' != 'value1'

Patch is attached. Edit kubedifflib/_diff.py and build container with build instructions in doc except “make .uptodate” instead of “make” to bypass tests. patch.txt