Samarthya

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Cert-Manager: TLS for ingress

Saksham 1 year ago

A common use-case for cert-manager is requesting TLS signed certificates to secure your ingress resources.

cert-manager adds certificates and certificate issuers as resource types in Kubernetes clusters, and simplifies the process of obtaining, renewing and using those certificates.

Installation

The easiest way is to use helm charts.

helm repo add jetstack https://charts.jetstack.io
root@master>helm repo list
NAME                    URL                                                                                         
stable                  https://charts.helm.sh/stable                                                                                                        
jetstack                https://charts.jetstack.io  
helm install cert-manager jetstack/cert-manager \
  --namespace cert-manager \
  --create-namespace \
  --version v1.7.1 \
  --set prometheus.enabled=false \
  --set webhook.timeoutSeconds=4 \
  --set installCRDs=true

Once deployed you can see the k8s objects deployed

root@master>k get all -n cert-manager
NAME                                           READY   STATUS    RESTARTS   AGE
pod/cert-manager-86f4f985d6-ntgtf              1/1     Running   0          7d23h
pod/cert-manager-cainjector-56bc5f744c-tdhx6   1/1     Running   0          7d23h
pod/cert-manager-webhook-997b5dd88-4jbmf       1/1     Running   0          7d23h

NAME                           TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)    AGE
service/cert-manager           ClusterIP   10.100.35.73   <none>        9402/TCP   67d
service/cert-manager-webhook   ClusterIP   10.96.67.112   <none>        443/TCP    67d

NAME                                      READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/cert-manager              1/1     1            1           67d
deployment.apps/cert-manager-cainjector   1/1     1            1           67d
deployment.apps/cert-manager-webhook      1/1     1            1           67d

NAME                                                 DESIRED   CURRENT   READY   AGE
replicaset.apps/cert-manager-57d89b9548              0         0         0       67d
replicaset.apps/cert-manager-86f4f985d6              1         1         1       7d23h
replicaset.apps/cert-manager-cainjector-56bc5f744c   1         1         1       7d23h
replicaset.apps/cert-manager-cainjector-5bcf77b697   0         0         0       67d
replicaset.apps/cert-manager-webhook-997b5dd88       1         1         1       7d23h
replicaset.apps/cert-manager-webhook-9cb88bd6d       0         0         0       67d

Example

>kubectl get Issuers,ClusterIssuers,Certificates,CertificateRequests,Orders,Challenges -A

Issuers

NAMESPACE           NAME                                          READY   AGE
cert-manager-test   issuer.cert-manager.io/test-selfsigned        True    7d21h
jenkins             issuer.cert-manager.io/jenkins-selfsigned     True    6d18h
spinnaker           issuer.cert-manager.io/spinnaker-selfsigned   True    7d21h
NAMESPACE           NAME                                            READY   SECRET                AGE
cert-manager-test   certificate.cert-manager.io/selfsigned-cert     True    selfsigned-cert-tls   7d21h
jenkins             certificate.cert-manager.io/jenkinsdevops.com   True    jenkinsdevops.com     6d18h
spinnaker           certificate.cert-manager.io/devops.com          True    devops.com            7d19h
spinnaker           certificate.cert-manager.io/selfsigned-cert     True    devops.com            7d21h
NAMESPACE           NAME                                                         APPROVED   DENIED   READY   ISSUER                 REQUESTOR                                         AGE
cert-manager-test   certificaterequest.cert-manager.io/selfsigned-cert-hnd85     True                True    test-selfsigned        system:serviceaccount:cert-manager:cert-manager   7d21h
jenkins             certificaterequest.cert-manager.io/jenkinsdevops.com-75hdn   True                True    jenkins-selfsigned     system:serviceaccount:cert-manager:cert-manager   6d18h
spinnaker           certificaterequest.cert-manager.io/devops.com-g6b2m          True                True    spinnaker-selfsigned   system:serviceaccount:cert-manager:cert-manager   5d22h
spinnaker           certificaterequest.cert-manager.io/devops.com-rz6db          True                True    spinnaker-selfsigned   system:serviceaccount:cert-manager:cert-manager   5d23h
spinnaker           certificaterequest.cert-manager.io/devops.com-wzs4h          True                True    spinnaker-selfsigned   system:serviceaccount:cert-manager:cert-manager   5d22h
spinnaker           certificaterequest.cert-manager.io/selfsigned-cert-mfggn     True                True    spinnaker-selfsigned   system:serviceaccount:cert-manager:cert-manager   7d21h

After Installation, Configure

The first thing you’ll need to configure after you’ve installed cert-manager is an issuer which you can then use to issue certificates.

Before you begin

Issuers & ClusterIssuer

Issuers, and ClusterIssuers, are Kubernetes resources that represent certificate authorities (CAs) that are able to generate signed certificates by honoring certificate signing requests.

Example – Issuer

apiVersion: cert-manager.io/v1
kind: Issuer
metadata:
  name: jenkins-selfsigned
  namespace: jenkins
spec:
  selfSigned: {}

Example – ClusterIssuer

apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
  name: selfsigned-cluster-issuer
spec:
  selfSigned: {}

An Issuer is a namespaced resource, and it is not possible to issue certificates from an Issuer in a different namespace. 

If you want to create a single Issuer that can be consumed in multiple namespaces, you should consider creating a ClusterIssuer resource. 

Certificate

A Certificate is a namespaced resource that references an Issuer or ClusterIssuer that determine what will be honoring the certificate request.

When a Certificate is created, a corresponding CertificateRequest resource is created by cert-manager containing the encoded X.509 certificate request, Issuer reference, and other options based upon the specification of the Certificate resource.

Securing Ingress

As I conclude the blog, let me use the deployed cert-manager to secure the TLS deployment for my spinnaker instance.

Supported Annotations in Ingress: https://cert-manager.io/docs/usage/ingress/#supported-annotations

In our example we will use mostly

  • cert-manager.io/issuer
  • cert-manager.io/cluster-issuer

Deployed Spinnaker Pods

root@master>k get pods -n spinnaker
NAME                                  READY   STATUS    RESTARTS   AGE
minio-5bbd54df5b-qnfvs                1/1     Running   0          8d
spin-clouddriver-ddd75554c-tts9z      1/1     Running   0          45h
spin-deck-649d97f44f-kp59x            1/1     Running   0          8d
spin-echo-9587cdc9d-gm7pt             1/1     Running   0          4d16h
spin-front50-7dbbb7668-qpr5f          1/1     Running   0          5d23h
spin-gate-69b9f88748-pppwm            1/1     Running   0          5d23h
spin-igor-6bcc768f9c-fzr8c            1/1     Running   0          47h
spin-orca-68ff75b6f8-r6872            1/1     Running   0          5d23h
spin-redis-864dff6b7-82m55            1/1     Running   0          8d
spin-rosco-68dc887685-sm9p8           1/1     Running   0          5d23h

Services

root@master>k get svc -n spinnaker
NAME                  TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
minio                 ClusterIP   10.96.179.180    <none>        9000/TCP   8d
spin-clouddriver      ClusterIP   10.107.86.175    <none>        7002/TCP   8d
spin-deck             ClusterIP   10.106.159.232   <none>        9000/TCP   8d
spin-echo             ClusterIP   10.98.31.29      <none>        8089/TCP   8d
spin-front50          ClusterIP   10.106.148.148   <none>        8080/TCP   8d
spin-gate             ClusterIP   10.105.124.157   <none>        8084/TCP   8d
spin-igor             ClusterIP   10.99.29.79      <none>        8088/TCP   5d23h
spin-orca             ClusterIP   10.103.240.238   <none>        8083/TCP   8d
spin-redis            ClusterIP   10.99.134.213    <none>        6379/TCP   8d
spin-rosco            ClusterIP   10.110.22.96     <none>        8087/TCP   8d

I will use the Ingress to expose the UI and API

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  annotations:
    haproxy.org/cors-allow-origin: "*.devops.com"
    haproxy.org/ingress.class: haproxy
    cert-manager.io/issuer: "spinnaker-selfsigned"
    cert-manager.io/common-name: "devops.com"
  name: spinnaker-ingress
  namespace: spinnaker
spec:
  ingressClassName: haproxy
  rules:
  - host: ui.devops.com
    http:
      paths:
      - backend:
          service:
            name: spin-deck
            port:
              number: 9000
        path: /
        pathType: Prefix
  - host: api.devops.com
    http:
      paths:
      - backend:
          service:
            name: spin-gate
            port:
              number: 8084
        path: /
        pathType: Prefix
  tls:
  - hosts:
    - ui.devops.com
    - api.devops.com
    secretName: devops.com

Please note the annotation cert-manager.io/issuer: "spinnaker-selfsigned" applied to the ingress once the resource is created using kubectl create -f <yaml>

k get ing -n spinnaker
NAME                  CLASS     HOSTS                                                 ADDRESS          PORTS     AGE
spinnaker-ingress     haproxy   ui.devops.com,api.devops.com,clouddriver.devops.com   10.98.117.100    80, 443   7d21h

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