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      How To Set Up an Nginx Ingress on DigitalOcean Kubernetes Using Helm


      The author selected the Free and Open Source Fund to receive a donation as part of the Write for DOnations program.

      Introduction

      Kubernetes Ingresses offer you a flexible way of routing traffic from beyond your cluster to internal Kubernetes Services. Ingress Resources are objects in Kubernetes that define rules for routing HTTP and HTTPS traffic to Services. For these to work, an Ingress Controller must be present; its role is to implement the rules by accepting traffic (most likely via a Load Balancer) and routing it to the appropriate Services. Most Ingress Controllers use only one global Load Balancer for all Ingresses, which is more efficient than creating a Load Balancer per every Service you wish to expose.

      Helm is a package manager for managing Kubernetes. Using Helm Charts with your Kubernetes provides configurability and lifecycle management to update, rollback, and delete a Kubernetes application.

      In this guide, you’ll set up the Kubernetes-maintained Nginx Ingress Controller using Helm. You’ll then create an Ingress Resource to route traffic from your domains to example Hello World back-end services. Once you’ve set up the Ingress, you’ll install Cert-Manager to your cluster to be able to automatically provision Let’s Encrypt TLS certificates to secure your Ingresses.

      Prerequisites

      • A DigitalOcean Kubernetes cluster with your connection configuration configured as the kubectl default. Instructions on how to configure kubectl are shown under the Connect to your Cluster step shown when you create your cluster. To learn how to create a Kubernetes cluster on DigitalOcean, see Kubernetes Quickstart.

      • The Helm package manager installed on your local machine, and Tiller installed on your cluster. Complete steps 1 and 2 of the How To Install Software on Kubernetes Clusters with the Helm Package Manager tutorial.

      • A fully registered domain name with two available A records. This tutorial will use hw1.example.com and hw2.example.com throughout. You can purchase a domain name on Namecheap, get one for free on Freenom, or use the domain registrar of your choice.

      Step 1 — Setting Up Hello World Deployments

      In this section, before you deploy the Nginx Ingress, you will deploy a Hello World app called hello-kubernetes to have some Services to which you’ll route the traffic. To confirm that the Nginx Ingress works properly in the next steps, you’ll deploy it twice, each time with a different welcome message that will be shown when you access it from your browser.

      You’ll store the deployment configuration on your local machine. The first deployment configuration will be in a file named hello-kubernetes-first.yaml. Create it using a text editor:

      • nano hello-kubernetes-first.yaml

      Add the following lines:

      hello-kubernetes-first.yaml

      apiVersion: v1
      kind: Service
      metadata:
        name: hello-kubernetes-first
      spec:
        type: ClusterIP
        ports:
        - port: 80
          targetPort: 8080
        selector:
          app: hello-kubernetes-first
      ---
      apiVersion: apps/v1
      kind: Deployment
      metadata:
        name: hello-kubernetes-first
      spec:
        replicas: 3
        selector:
          matchLabels:
            app: hello-kubernetes-first
        template:
          metadata:
            labels:
              app: hello-kubernetes-first
          spec:
            containers:
            - name: hello-kubernetes
              image: paulbouwer/hello-kubernetes:1.5
              ports:
              - containerPort: 8080
              env:
              - name: MESSAGE
                value: Hello from the first deployment!
      

      This configuration defines a Deployment and a Service. The Deployment consists of three replicas of the paulbouwer/hello-kubernetes:1.5 image, and an environment variable named MESSAGE—you will see its value when you access the app. The Service here is defined to expose the Deployment in-cluster at port 80.

      Save and close the file.

      Then, create this first variant of the hello-kubernetes app in Kubernetes by running the following command:

      • kubectl create -f hello-kubernetes-first.yaml

      You’ll see the following output:

      Output

      service/hello-kubernetes-first created deployment.apps/hello-kubernetes-first created

      To verify the Service’s creation, run the following command:

      • kubectl get service hello-kubernetes-first

      The output will look like this:

      Output

      NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE hello-kubernetes-first ClusterIP 10.245.85.236 <none> 80:31623/TCP 35s

      You’ll see that the newly created Service has a ClusterIP assigned, which means that it is working properly. All traffic sent to it will be forwarded to the selected Deployment on port 8080. Now that you have deployed the first variant of the hello-kubernetes app, you’ll work on the second one.

      Open a file called hello-kubernetes-second.yaml for editing:

      • nano hello-kubernetes-second.yaml

      Add the following lines:

      hello-kubernetes-second.yaml

      apiVersion: v1
      kind: Service
      metadata:
        name: hello-kubernetes-second
      spec:
        type: ClusterIP
        ports:
        - port: 80
          targetPort: 8080
        selector:
          app: hello-kubernetes-second
      ---
      apiVersion: apps/v1
      kind: Deployment
      metadata:
        name: hello-kubernetes-second
      spec:
        replicas: 3
        selector:
          matchLabels:
            app: hello-kubernetes-second
        template:
          metadata:
            labels:
              app: hello-kubernetes-second
          spec:
            containers:
            - name: hello-kubernetes
              image: paulbouwer/hello-kubernetes:1.5
              ports:
              - containerPort: 8080
              env:
              - name: MESSAGE
                value: Hello from the second deployment!
      

      Save and close the file.

      This variant has the same structure as the previous configuration; the only differences are in the Deployment and Service names, to avoid collisions, and the message.

      Now create it in Kubernetes with the following command:

      • kubectl create -f hello-kubernetes-second.yaml

      The output will be:

      Output

      service/hello-kubernetes-second created deployment.apps/hello-kubernetes-second created

      Verify that the second Service is up and running by listing all of your services:

      The output will be similar to this:

      Output

      NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE hello-kubernetes-first ClusterIP 10.245.85.236 <none> 80:31623/TCP 54s hello-kubernetes-second ClusterIP 10.245.99.130 <none> 80:30303/TCP 12s kubernetes ClusterIP 10.245.0.1 <none> 443/TCP 5m

      Both hello-kubernetes-first and hello-kubernetes-second are listed, which means that Kubernetes has created them successfully.

      You've created two deployments of the hello-kubernetes app with accompanying Services. Each one has a different message set in the deployment specification, which allow you to differentiate them during testing. In the next step, you'll install the Nginx Ingress Controller itself.

      Step 2 — Installing the Kubernetes Nginx Ingress Controller

      Now you'll install the Kubernetes-maintained Nginx Ingress Controller using Helm. Note that there are several Nginx Ingresses.

      The Nginx Ingress Controller consists of a Pod and a Service. The Pod runs the Controller, which constantly polls the /ingresses endpoint on the API server of your cluster for updates to available Ingress Resources. The Service is of type LoadBalancer, and because you are deploying it to a DigitalOcean Kubernetes cluster, the cluster will automatically create a DigitalOcean Load Balancer, through which all external traffic will flow to the Controller. The Controller will then route the traffic to appropriate Services, as defined in Ingress Resources.

      Only the LoadBalancer Service knows the IP address of the automatically created Load Balancer. Some apps (such as ExternalDNS) need to know its IP address, but can only read the configuration of an Ingress. The Controller can be configured to publish the IP address on each Ingress by setting the controller.publishService.enabled parameter to true during helm install. It is recommended to enable this setting to support applications that may depend on the IP address of the Load Balancer.

      To install the Nginx Ingress Controller to your cluster, run the following command:

      • helm install stable/nginx-ingress --name nginx-ingress --set controller.publishService.enabled=true

      This command installs the Nginx Ingress Controller from the stable charts repository, names the Helm release nginx-ingress, and sets the publishService parameter to true.

      The output will look like:

      Output

      NAME: nginx-ingress LAST DEPLOYED: ... NAMESPACE: default STATUS: DEPLOYED RESOURCES: ==> v1/ConfigMap NAME DATA AGE nginx-ingress-controller 1 0s ==> v1/Pod(related) NAME READY STATUS RESTARTS AGE nginx-ingress-controller-7658988787-npv28 0/1 ContainerCreating 0 0s nginx-ingress-default-backend-7f5d59d759-26xq2 0/1 ContainerCreating 0 0s ==> v1/Service NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE nginx-ingress-controller LoadBalancer 10.245.9.107 <pending> 80:31305/TCP,443:30519/TCP 0s nginx-ingress-default-backend ClusterIP 10.245.221.49 <none> 80/TCP 0s ==> v1/ServiceAccount NAME SECRETS AGE nginx-ingress 1 0s ==> v1beta1/ClusterRole NAME AGE nginx-ingress 0s ==> v1beta1/ClusterRoleBinding NAME AGE nginx-ingress 0s ==> v1beta1/Deployment NAME READY UP-TO-DATE AVAILABLE AGE nginx-ingress-controller 0/1 1 0 0s nginx-ingress-default-backend 0/1 1 0 0s ==> v1beta1/Role NAME AGE nginx-ingress 0s ==> v1beta1/RoleBinding NAME AGE nginx-ingress 0s NOTES: ...

      Helm has logged what resources in Kubernetes it created as a part of the chart installation.

      You can watch the Load Balancer become available by running:

      • kubectl get services -o wide -w nginx-ingress-controller

      You've installed the Nginx Ingress maintained by the Kubernetes community. It will route HTTP and HTTPS traffic from the Load Balancer to appropriate back-end Services, configured in Ingress Resources. In the next step, you'll expose the hello-kubernetes app deployments using an Ingress Resource.

      Step 3 — Exposing the App Using an Ingress

      Now you're going to create an Ingress Resource and use it to expose the hello-kubernetes app deployments at your desired domains. You'll then test it by accessing it from your browser.

      You'll store the Ingress in a file named hello-kubernetes-ingress.yaml. Create it using your editor:

      • nano hello-kubernetes-ingress.yaml

      Add the following lines to your file:

      hello-kubernetes-ingress.yaml

      apiVersion: extensions/v1beta1
      kind: Ingress
      metadata:
        name: hello-kubernetes-ingress
        annotations:
          kubernetes.io/ingress.class: nginx
      spec:
        rules:
        - host: hw1.example.com
          http:
            paths:
            - backend:
                serviceName: hello-kubernetes-first
                servicePort: 80
        - host: hw2.example.com
          http:
            paths:
            - backend:
                serviceName: hello-kubernetes-second
                servicePort: 80
      

      In the code above, you define an Ingress Resource with the name hello-kubernetes-ingress. Then, you specify two host rules, so that hw1.example.com is routed to the hello-kubernetes-first Service, and hw2.example.com is routed to the Service from the second deployment (hello-kubernetes-second).

      Remember to replace the highlighted domains with your own, then save and close the file.

      Create it in Kubernetes by running the following command:

      • kubectl create -f hello-kubernetes-ingress.yaml

      Next, you'll need to ensure that your two domains are pointed to the Load Balancer via A records. This is done through your DNS provider. To configure your DNS records on DigitalOcean, see How to Manage DNS Records.

      You can now navigate to hw1.example.com in your browser. You will see the following:

      Hello Kubernetes - First Deployment

      The second variant (hw2.example.com) will show a different message:

      Hello Kubernetes - Second Deployment

      With this, you have verified that the Ingress Controller correctly routes requests; in this case, from your two domains to two different Services.

      You've created and configured an Ingress Resource to serve the hello-kubernetes app deployments at your domains. In the next step, you'll set up Cert-Manager, so you'll be able to secure your Ingress Resources with free TLS certificates from Let's Encrypt.

      Step 4 — Securing the Ingress Using Cert-Manager

      To secure your Ingress Resources, you'll install Cert-Manager, create a ClusterIssuer for production, and modify the configuration of your Ingress to take advantage of the TLS certificates. ClusterIssuers are Cert-Manager Resources in Kubernetes that provision TLS certificates. Once installed and configured, your app will be running behind HTTPS.

      Before installing Cert-Manager to your cluster via Helm, you'll manually apply the required CRDs (Custom Resource Definitions) from the jetstack/cert-manager repository by running the following command:

      • kubectl apply -f https://raw.githubusercontent.com/jetstack/cert-manager/release-0.8/deploy/manifests/00-crds.yaml

      You will see the following output:

      Output

      customresourcedefinition.apiextensions.k8s.io/certificates.certmanager.k8s.io created customresourcedefinition.apiextensions.k8s.io/challenges.certmanager.k8s.io created customresourcedefinition.apiextensions.k8s.io/clusterissuers.certmanager.k8s.io created customresourcedefinition.apiextensions.k8s.io/issuers.certmanager.k8s.io created customresourcedefinition.apiextensions.k8s.io/orders.certmanager.k8s.io created

      This shows that Kubernetes has applied the custom resources you require for cert-manager.

      Note: If you've followed this tutorial and the prerequisites, you haven't created a Kubernetes namespace called cert-manager, so you won't have to run the command in this note block. However, if this namespace does exist on your cluster, you'll need to inform Cert-Manager not to validate it with the following command:

      • kubectl label namespace cert-manager certmanager.k8s.io/disable-validation="true"

      The Webhook component of Cert-Manager requires TLS certificates to securely communicate with the Kubernetes API server. In order for Cert-Manager to generate certificates for it for the first time, resource validation must be disabled on the namespace it is deployed in. Otherwise, it would be stuck in an infinite loop; unable to contact the API and unable to generate the TLS certificates.

      The output will be:

      Output

      namespace/cert-manager labeled

      Next, you'll need to add the Jetstack Helm repository to Helm, which hosts the Cert-Manager chart. To do this, run the following command:

      • helm repo add jetstack https://charts.jetstack.io

      Helm will display the following output:

      Output

      "jetstack" has been added to your repositories

      Finally, install Cert-Manager into the cert-manager namespace:

      • helm install --name cert-manager --namespace cert-manager jetstack/cert-manager

      You will see the following output:

      Output

      NAME: cert-manager LAST DEPLOYED: ... NAMESPACE: cert-manager STATUS: DEPLOYED RESOURCES: ==> v1/ClusterRole NAME AGE cert-manager-edit 3s cert-manager-view 3s cert-manager-webhook:webhook-requester 3s ==> v1/Pod(related) NAME READY STATUS RESTARTS AGE cert-manager-5d669ffbd8-rb6tr 0/1 ContainerCreating 0 2s cert-manager-cainjector-79b7fc64f-gqbtz 0/1 ContainerCreating 0 2s cert-manager-webhook-6484955794-v56lx 0/1 ContainerCreating 0 2s ... NOTES: cert-manager has been deployed successfully! In order to begin issuing certificates, you will need to set up a ClusterIssuer or Issuer resource (for example, by creating a 'letsencrypt-staging' issuer). More information on the different types of issuers and how to configure them can be found in our documentation: https://docs.cert-manager.io/en/latest/reference/issuers.html For information on how to configure cert-manager to automatically provision Certificates for Ingress resources, take a look at the `ingress-shim` documentation: https://docs.cert-manager.io/en/latest/reference/ingress-shim.html

      The output shows that the installation was successful. As listed in the NOTES in the output, you'll need to set up an Issuer to issue TLS certificates.

      You'll now create one that issues Let's Encrypt certificates, and you'll store its configuration in a file named production_issuer.yaml. Create it and open it for editing:

      • nano production_issuer.yaml

      Add the following lines:

      production_issuer.yaml

      apiVersion: certmanager.k8s.io/v1alpha1
      kind: ClusterIssuer
      metadata:
        name: letsencrypt-prod
      spec:
        acme:
          # The ACME server URL
          server: https://acme-v02.api.letsencrypt.org/directory
          # Email address used for ACME registration
          email: your_email_address
          # Name of a secret used to store the ACME account private key
          privateKeySecretRef:
            name: letsencrypt-prod
          # Enable the HTTP-01 challenge provider
          http01: {}
      

      This configuration defines a ClusterIssuer that contacts Let's Encrypt in order to issue certificates. You'll need to replace your_email_address with your email address in order to receive possible urgent notices regarding the security and expiration of your certificates.

      Save and close the file.

      Roll it out with kubectl:

      • kubectl create -f production_issuer.yaml

      You will see the following output:

      Output

      clusterissuer.certmanager.k8s.io/letsencrypt-prod created

      With Cert-Manager installed, you're ready to introduce the certificates to the Ingress Resource defined in the previous step. Open hello-kubernetes-ingress.yaml for editing:

      • nano hello-kubernetes-ingress.yaml

      Add the highlighted lines:

      hello-kubernetes-ingress.yaml

      apiVersion: extensions/v1beta1
      kind: Ingress
      metadata:
        name: hello-kubernetes-ingress
        annotations:
          kubernetes.io/ingress.class: nginx
          certmanager.k8s.io/cluster-issuer: letsencrypt-prod
      spec:
        tls:
        - hosts:
          - hw1.example.com
          - hw2.example.com
          secretName: letsencrypt-prod
        rules:
        - host: hw1.example.com
          http:
            paths:
            - backend:
                serviceName: hello-kubernetes-first
                servicePort: 80
        - host: hw2.example.com
          http:
            paths:
            - backend:
                serviceName: hello-kubernetes-second
                servicePort: 80
      

      The tls block under spec defines in what Secret the certificates for your sites (listed under hosts) will store their certificates, which the letsencrypt-prod ClusterIssuer issues. This must be different for every Ingress you create.

      Remember to replace the hw1.example.com and hw2.example.com with your own domains. When you've finished editing, save and close the file.

      Re-apply this configuration to your cluster by running the following command:

      • kubectl apply -f hello-kubernetes-ingress.yaml

      You will see the following output:

      Output

      ingress.extensions/hello-kubernetes-ingress configured

      You'll need to wait a few minutes for the Let's Encrypt servers to issue a certificate for your domains. In the meantime, you can track its progress by inspecting the output of the following command:

      • kubectl describe certificate hello-kubernetes

      The end of the output will look similar to this:

      Output

      Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Generated 56s cert-manager Generated new private key Normal GenerateSelfSigned 56s cert-manager Generated temporary self signed certificate Normal OrderCreated 56s cert-manager Created Order resource "hello-kubernetes-1197334873" Normal OrderComplete 31s cert-manager Order "hello-kubernetes-1197334873" completed successfully Normal CertIssued 31s cert-manager Certificate issued successfully

      When your last line of output reads Certificate issued successfully, you can exit by pressing CTRL + C. Navigate to one of your domains in your browser to test. You'll see the padlock to the left of the address bar in your browser, signifying that your connection is secure.

      In this step, you have installed Cert-Manager using Helm and created a Let's Encrypt ClusterIssuer. After, you updated your Ingress Resource to take advantage of the Issuer for generating TLS certificates. In the end, you have confirmed that HTTPS works correctly by navigating to one of your domains in your browser.

      Conclusion

      You have now successfully set up the Nginx Ingress Controller and Cert-Manager on your DigitalOcean Kubernetes cluster using Helm. You are now able to expose your apps to the Internet, at your domains, secured using Let's Encrypt TLS certificates.

      For further information about the Helm package manager, read this introduction article.



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