In this tutorial, you will learn how to setup Kubernetes ingress using Nginx ingress controller and to route traffic to deployments using wildcard DNS.
If you want to understand how Kubernetes ingress works, please read this blog post on Kubernetes Ingress Tutorial.
Here is an example architecture of Kubernetes ingress using Nginx ingress controller
Prerequisites:
- A Kuberntes cluster
- kubectl utility installed and authenticated to kubernetes cluster.
- Admin access to kubernetes cluster.
- A valid domain to point to ingress controller Load Balancer.
If you are on google cloud, assign admin permissions to your account to enable cluster roles.
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ACCOUNT=$(gcloud info --format='value(config.account)') kubectl create clusterrolebinding owner-cluster-admin-binding \ --clusterrole cluster-admin \ --user $ACCOUNT |
Note: This tutorial was tried on google cloud GKE cluster. Logically it should work on all cloud environments. If at all you face any error, you might need to do some tweaks in the setup.
Setup Nginx Ingress Controller
There are two nginx ingress controllers.
We will be using the Nginx controller from the kubernetes community.
Ingress controller needs a specific namespace, service account, cluster role bindings, configmaps etc. You can create all the kubernetes objects mentioned using the yaml file from official ingress repo.
Let’s deploy the ingress controller using mandatory.yaml file from the official repo. It has the consolidated list of kubernetes objects required for the Nginx controller.
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Lets create the Nginx controller deployment using kubectl.
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kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/mandatory.yaml |
Check the ingress controller pods to make sure if it is setup correctly.
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kubectl get pods -n ingress-nginx |
Setup LoadBalancer Service For Ingress Controller
Next step is to create a service of Type Loadbalancer to expose the nginx controller deployment outside the cluster.
Step 1: Create a project directory locally and switch to that directory.
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mkdir ingress-deployment && cd ingress-deployment |
Step 2: Create a file named nginx-ingress.yaml
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vi nginx-ingress.yaml |
Step 3: Copy the following contents to the file.
Note: The annotations under the labels are very important for integrating with the nginx controller deployment.
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kind: Service apiVersion: v1 metadata: name: ingress-nginx namespace: ingress-nginx labels: app.kubernetes.io/name: ingress-nginx app.kubernetes.io/part-of: ingress-nginx spec: externalTrafficPolicy: Local type: LoadBalancer selector: app.kubernetes.io/name: ingress-nginx app.kubernetes.io/part-of: ingress-nginx ports: - name: http port: 80 targetPort: http - name: https port: 443 targetPort: https |
Step 4: Create the ingress service.
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kubectl apply -f nginx-ingress.yaml |
Step 5: Check the created service if it is attached to the external load balancer.
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kubectl get svc -n ingress-nginx |
Map a Domain Name To Loadbalancer IP
To make our ingress settings work, we need to map a domain name to the load balancer IP. You can do it in two ways.
Single DNS Mapping:
You can map single domain directly as a A record to the load balancer IP. Using this you can have only one domain for the ingress controller and multiple path based traffic routing.
For example,
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www.example.com --> Loadbalancer IP |
You can have path based routing using this model.
Few examples,
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http://www.example.com/app1 http://www.example.com/app2 http://www.example.com/app1/api http://www.example.com/app2/api |
Wildcard DNS Mapping:
If you map a wildcard DNS to the load balancer, you can have dynamic DNS end points through ingress.
For example,
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*.apps.example.com |
This way you can have multiple dynamic subdomains through single ingress controller and each DNS can have its own path based routing.
For example,
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#URL one http://demo1.apps.example.com/api http://demo1.apps.example.com/api/v1 http://demo1.apps.example.com/api/v2 #URL two http://demo2.apps.example.com/api http://demo2.apps.example.com/api/v1 http://demo2.apps.example.com/api/v2 |
For demo purposes, we have mapped a wildcard DNS to the LoadBalancer IP. Based on your DNS provider, you can do this setting.
Setup A Demo Application
For testing purposes, we will deploy a demo application and add a ClusterIp service to it.
Also Read: Kubernetes deployment tutorial
Step 1: create a namespace named dev
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kubectl create namespace dev |
Step 2: Create a file named hello-app.yaml
Step 3: Copy the following contents and save the file.
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apiVersion: apps/v1 kind: Deployment metadata: name: hello-app namespace: dev spec: selector: matchLabels: app: hello replicas: 3 template: metadata: labels: app: hello spec: containers: - name: hello image: "gcr.io/google-samples/hello-app:2.0" |
Step 4: Create the deployment using kubectl
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kubectl create -f hello-app.yaml |
Check the deployment status.
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kubectl get deployments -n dev |
Step 5: Create a file named hello-app-service.yaml
Step 6: Copy the following contents and save the file.
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apiVersion: v1 kind: Service metadata: name: hello-service namespace: dev labels: app: hello spec: type: ClusterIP selector: app: hello ports: - port: 80 targetPort: 8080 protocol: TCP |
Step 7: Create the service using kubectl.
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kubectl create -f hello-app-service.yaml |
Check the service status
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kubectl get svc -n dev |
Create Kubernetes Ingress Object
Now let’s create an ingress object to access our hello app using a DNS. An ingress object is nothing but a setup of routing rules.
If you are wondering how ingress object is connected to Nginx controller, the ingress controller pod connects to the Ingress API to check for rules and it updates its nginx.conf accordingly.
Step 1: Create a file named ingress.yaml
Step 2: Copy the following contents and save the file.
Replace test.apps.example.info with your domain name. Here the assumption is that you have a wildcard DNS in the format *.apps.example.info
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apiVersion: extensions/v1beta1 kind: Ingress metadata: name: test-ingress namespace: dev spec: rules: - host: test.apps.example.info http: paths: - backend: serviceName: hello-service servicePort: 80 |
Step 3: Describe created ingress object created to check the configurations.
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kubectl describe ingress -n dev |
Now if you try to access test.apps.example.info domain (replace it with your domain name), you should be able to access our sample app deployed.
