Invalid Spec Selector After Upgrading Helm Template

Question

I've upgraded helm templates (by hand)

Fragment of previous depoloyment.yaml:

apiVersion: apps/v1beta2 kind: Deployment metadata:   name: {{ template "measurement-collector.fullname" . }}   labels:
    app: {{ template "measurement-collector.name" . }}
    chart: {{ template "measurement-collector.chart" . }}
    release: {{ .Release.Name }}
    heritage: {{ .Release.Service }} spec:   replicas: {{ .Values.replicaCount }}   selector:
    matchLabels:
      app: {{ template "measurement-collector.name" . }}
      release: {{ .Release.Name }}

New one:

apiVersion: apps/v1beta2
kind: Deployment
metadata:
  name: {{ include "measurement-collector.fullname" . }}
  labels:
     {{ include "measurement-collector.name" . }}
     {{ include "measurement-collector.chart" . }}
     {{ .Release.Name }}
     {{ .Release.Service }}
spec:
  replicas: {{ .Values.replicaCount }}
  selector:
    matchLabels:
       {{ include "measurement-collector.name" . }}
       {{ .Release.Name }}

new service.yaml:

  name: {{ include "measurement-collector.fullname" . }}
  labels:
     {{ include "measurement-collector.name" . }}
     {{ include "measurement-collector.chart" . }}
     {{ .Release.Name }}
     {{ .Release.Service }}
spec:
  type: {{ .Values.service.type }}
  ports:
      protocol: TCP
      name: http
  selector:
     {{ include "measurement-collector.name" . }}
     {{ .Release.Name }}

Then after running: helm upgrade -i measurement-collector chart/measurement-collector --namespace prod --wait

I get:

Error: UPGRADE FAILED: Deployment.apps "measurement-collector" is invalid: spec.selector: Invalid value: 
v1.LabelSelector{MatchLabels:map[string]string{"":"measurement-collector", "":"measurement-collector"},         
MatchExpressions:[]v1.LabelSelectorRequirement(nil)}: field is immutable

Accepted Answer

If you change the selector label, then you will need to purge the release first before deploying.

Answer 2

Though @TigerBear answer is correct, I think I need to explain it in a little bit more details. This problem is caused by a simple reason - immutability of the selectors. You cannot update selectors for (I am not sure this is the complete list, feel free to correct me):

ReplicasSets
Deployments
DaemonSets

In other words, for example if you have a Deployment with label 'my-app: ABC' within selectors, after that you have updated label inside selector onto this: 'my-app: XYZ', and then simply applied this changes, e.g. like this:

kubectl apply -f deployment-file-name.yml

it will not work - you have to recreate the deployment.

Related github k8s issue, also there is a little note about it in the Deployment doc

Answer 3

The other answers are correct but I didn't understand them because I was dealing with a helm chart. In my case, I changed the helm chart name and got a similar error.

The change I made in my helm/Chart.yaml was

apiVersion: v2
name: my-app  ==> was changed to ==> my-new-app
description: A Helm chart for Kubernetes

I didn't realize that that change is used to name other things in the template. In particular, the deployment was changed as well. For example,

# Source: my-app/templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
spec:
  replicas: 1
  selector:
    matchLabels:
       my-app       <<< THIS became my-new-app
       my-app   <<< THIS became my-new-app

So the error was actually related to something that I didn't directly edit, which is why (to me) the error message was confusing.

By changing the Chart Name the selector was changed and that is not allowed when running helm upgrade. I also realize the underlying reason helm upgrade fails is because kubernetes doesn't support this.

Invalid Spec Selector After Upgrading Helm Template

3 Answers

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Sophia Al-Mansoor

Invalid Spec Selector After Upgrading Helm Template

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Sophia Al-Mansoor