Problem Statement

• I want to deliver a private registry which all the images I need for my product bundled in them ( Yes, It will be fat image, but I am fine with that)
• I would manually upload this image in some way
• I would run the docker private registry as a service in Kubernetes (probably in some namespace)
• When other services/deployments (in the same namespace as registry) happen in Kubernetes, they should refer to this registry using a consistent name

Constraints

• We want registry to be exposed only to the cluster and not outside
• We want to use self signed certificate and not signed by CA

I followed some instructions from these links (do not know whether it was a right thing to do)

• https://kubernetes.io/docs/concepts/cluster-administration/certificates/
• https://kubernetes.io/docs/tasks/tls/managing-tls-in-a-cluster/#create-a-certificate-signing-request-object-to-send-to-the-kubernetes-api

Create a certificate signed through Kubernetes

1. Create a server.key

2. Create a csr.info

[ req ]
default_bits = 2048
prompt = no
default_md = sha256
req_extensions = req_ext
distinguished_name = dn

[ dn ]
C = US
ST = oh
L = cincinnati
O = engg
OU = prod
CN = prateek.svc.cluster.local

[ req_ext ]
subjectAltName = @alt_names

[ alt_names ]
DNS.1 = registry.prateek.svc.cluster.local

[ v3_ext ]
authorityKeyIdentifier=keyid,issuer:always
basicConstraints=CA:FALSE
keyUsage=keyEncipherment,dataEncipherment
extendedKeyUsage=serverAuth,clientAuth
subjectAltName=@alt_names

3. Created the server.csr (openssl req -new -key server.key -out server.csr -config csr.conf)

4. Create the CertificateSigningRequest in K8s

cat <<EOF | kubectl apply -f -
apiVersion: certificates.k8s.io/v1beta1
kind: CertificateSigningRequest
metadata:
name: registry.prateek
spec:
groups:
- system:authenticated
request: $(cat server.csr | base64 | tr -d '\n')
usages:
- digital signature
- key encipherment
- server auth
EOF

5. Checked if the CSR exists

kubectl describe csr registry.prateek
Name: registry.prateek
Labels: <none>
Annotations: kubectl.kubernetes.io/last-applied-configuration={"apiVersion":"certificates.k8s.io/v1beta1","kind":"CertificateSigningRequest","metadata":{"annotations":{},"name":"registry.prateek","namespace":""},"spec":{"groups":["system:authenticated"],"request":"LS0sdfsfsdsfd=","usages":["digital signature","key encipherment","server auth"]}}

CreationTimestamp: Thu, 11 Apr 2019 11:15:42 -0400
Requesting User: docker-for-desktop
Status: Pending
Subject:
Common Name: prateek.svc.cluster.local
Serial Number:
Organization: engg
Organizational Unit: prod
Country: US
Locality: cincinnati
Province: oh
Subject Alternative Names:
DNS Names: registry.prateek.svc.cluster.local
Events: <none>

6. Approved the CSR : kubectl certificate approve registry.prateek

Start the registry internal service

7. Added cert and key to the kind: Secret

registry-secret.yml

apiVersion: v1
kind: Secret
metadata:
  name: registry-credentials
data:
  certificate: <CERTIFICATE in base64>
  key: <KEY in base64>

8. Create registry deployment and service (using those secrets) registry-deployment.yml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: registry
  namespace: prateek
  labels:
      app: registry
spec:
  replicas: 1
  selector:
    matchLabels:
      app: registry
  template:
    metadata:
      labels:
        app: registry
    spec:
      containers:
        - name: registry
          image: prateek/registry
          imagePullPolicy: IfNotPresent
          ports:
            - containerPort: 443
          env:
            - name: REGISTRY_HTTP_ADDR
              value: "0.0.0.0:443"
            - name: REGISTRY_HTTP_TLS_CERTIFICATE
              value: "/certs/certificate"
            - name: REGISTRY_HTTP_TLS_KEY
              value: "/certs/key"
          volumeMounts:
            - name: cert-files
              mountPath: /certs
      volumes:
        - name: cert-files
          secret:
            secretName: registry-credentials

registry-service.yml

apiVersion: v1
kind: Service
metadata:
  name: registry
  namespace: prateek
spec:
  selector:
    app: registry
  ports:
  - protocol: TCP
    port: 443
    targetPort: 443
  type: LoadBalancer

Test regsitry service is up

9. Tried to this the registry endpoint thru a test pod. I had image of this test pod loaded in docker already.

curl https://registry.prateek.svc.cluster.local/v2/_catalog -k
{"repositories":["prateek/echo"]}

Deployment using image from the registry service

10. Tried deployment with image: registry.prateek/prateek/echo:latest

apiVersion: apps/v1
kind: Deployment
metadata:
  name: hello
  namespace: cequence
  labels:
      app: hello
spec:
  replicas: 1
  selector:
    matchLabels:
      app: hello
  template:
    metadata:
      labels:
        app: hello
    spec:
      containers:
      - name: hello
        image: registry.prateek/prateek/echo:latest
        imagePullPolicy: IfNotPresent
        ports:
         - containerPort: 5678
        args: ["-text=hello"]

11. the deployment gives the error

Normal Pulling 10s (x2 over 25s) kubelet, docker-for-desktop pulling image "registry.prateek/prateek/echo:latest"
Warning Failed 10s (x2 over 25s) kubelet, docker-for-desktop Failed to pull image "registry.prateek/prateek/echo:latest": rpc error: code = Unknown desc = Error response from daemon: Get https://registry.prateek/v2/: Service Unavailable 

12. Changed deployment to have image: registry.prateek.svc.cluster.local/prateek/echo:latest

apiVersion: apps/v1
kind: Deployment
metadata:
  name: hello
  namespace: cequence
  labels:
      app: hello
spec:
  replicas: 1
  selector:
    matchLabels:
      app: hello
  template:
    metadata:
      labels:
        app: hello
    spec:
      containers:
      - name: hello
        image: registry.prateek.svc.cluster.local/prateek/echo:latest
        imagePullPolicy: IfNotPresent
        ports:
         - containerPort: 5678
        args: ["-text=hello"]

13. get the similar error

Warning Failed 1s kubelet, docker-for-desktop Failed to pull image "registry.prateek.svc.cluster.local/prateek/echo:latest": rpc error: code = Unknown desc = Error response from daemon: Get https://registry.prateek.svc.cluster.local/v2/: Service Unavailable

I do not that this is even possible. Run a docker registry as a service and point other service in the namespace to use that registry deployment in the cluster. Any suggestion is welcome