Deployment Yaml file - kubernetes

Question

I'm learning SQL Server BDC on minkube using this article as a guide. I tried deploying the below yaml file by running the code : kubectl apply -f deployment.yaml
apiVersion: apps/v1beta1
kind: Deployment
metadata:
name: mssql-deployment
spec:
replicas: 1
template:
metadata:
labels:
app: mssql
spec:
terminationGracePeriodSeconds: 10
containers:
- name: mssql
image: microsoft/mssql-server-linux
ports:
- containerPort: 1433
securityContext:
privileged: true
env:
- name: ACCEPT_EULA
value: "Y"
- name: SA_PASSWORD
valueFrom:
secretKeyRef:
name: mssql
key: SA_PASSWORD
volumeMounts:
- name: mssqldb
mountPath: /var/opt/mssql
volumes:
- name: mssqldb
persistentVolumeClaim:
claimName: pvc0001
It errored due to the v1beta1 APIVersion. I converted this yaml file by running : kubectl convert -f deployment.yaml and got the below script:
apiVersion: apps/v1
kind: Deployment
metadata:
creationTimestamp: null
name: mssql-deployment
spec:
progressDeadlineSeconds: 600
replicas: 1
revisionHistoryLimit: 10
selector: null
strategy:
rollingUpdate:
maxSurge: 25%
maxUnavailable: 25%
type: RollingUpdate
template:
metadata:
creationTimestamp: null
labels:
app: mssql
spec:
containers:
- env:
- name: ACCEPT_EULA
value: "Y"
- name: SA_PASSWORD
valueFrom:
secretKeyRef:
key: SA_PASSWORD
name: mssql
image: microsoft/mssql-server-linux
imagePullPolicy: Always
name: mssql
ports:
- containerPort: 1433
protocol: TCP
resources: {}
terminationMessagePath: /dev/termination-log
terminationMessagePolicy: File
dnsPolicy: ClusterFirst
restartPolicy: Always
schedulerName: default-scheduler
securityContext: {}
terminationGracePeriodSeconds: 10
status: {}
But when I deploy the above script I get:
Error validating "deployment.yaml": error validating data: ValidationError(Deployment.spec): missing required field "selector" in io.k8s.api.apps.v1.DeploymentSpec; if you choose to ignore these errors, turn validation off with --validate=false
It is related to matchlabels/matchexpressions but I'm not able to address it. Can someone point me in the right direction?

Answer 1

You need to add a selector in the spec section of the deployment. It's a mandatory field.The .spec.selector field defines how the Deployment finds which Pods to manage. In this case, you simply select a label that is defined in the Pod template (app: mssql). However, more sophisticated selection rules are possible, as long as the Pod template itself satisfies the rule.
apiVersion: apps/v1
kindapiVersion: apps/v1
kind: Deployment
metadata:
creationTimestamp: null
name: mssql-deployment
spec:
progressDeadlineSeconds: 600
replicas: 1
revisionHistoryLimit: 10
selector:
matchLabels:
app: mssql
strategy:
rollingUpdate:
maxSurge: 25%
maxUnavailable: 25%
type: RollingUpdate
template:
metadata:
creationTimestamp: null
labels:
app: mssql
spec:
containers:
- env:
- name: ACCEPT_EULA
value: "Y"
- name: SA_PASSWORD
valueFrom:
secretKeyRef:
key: SA_PASSWORD
name: mssql
image: microsoft/mssql-server-linux
imagePullPolicy: Always
name: mssql
ports:
- containerPort: 1433
protocol: TCP
resources: {}
terminationMessagePath: /dev/termination-log
terminationMessagePolicy: File
dnsPolicy: ClusterFirst
restartPolicy: Always
schedulerName: default-scheduler
securityContext: {}
terminationGracePeriodSeconds: 10
status: {}

Answer 2

missing required field "selector" in io.k8s.api.apps.v1.DeploymentSpec
You need a selector to select which pods are configured to deployment spec.
solution:
selector:
matchLabels:
app: mssql
template:
metadata:
labels:
app: mssql