Dual nginx in one Kubernetes pod

Question

I am doing a lab about kubernetes in google cloud , so my task is deploy two nginx servers in one pod, however I have a issue.

One of the pods can not starts, as PORT or IP is using buy another nginx container, I need to change it in yaml file, please give me a solution, thank you in advance

apiVersion: v1
kind: Pod
metadata:
  name: two-containers
spec:

  restartPolicy: Never

  volumes:
  - name: shared-data
    emptyDir: {}

  containers:

  - name: first-container
    image: nginx
  - name: second-container
    image: nginx

E  nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)

E  2019/01/21 11:04:47 [emerg] 1#1: bind() to 0.0.0.0:80 failed (98: Address already in use)

E  nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)

E  2019/01/21 11:04:47 [emerg] 1#1: bind() to 0.0.0.0:80 failed (98: Address already in use)

E  nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)

E  2019/01/21 11:04:47 [emerg] 1#1: bind() to 0.0.0.0:80 failed (98: Address already in use)

E  nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)

E  2019/01/21 11:04:47 [emerg] 1#1: bind() to 0.0.0.0:80 failed (98: Address already in use)

E  nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)

E  2019/01/21 11:04:47 [emerg] 1#1: still could not bind()

E  nginx: [emerg] still could not bind()

Answer 1

In kubernetes the container in pods share single network namespace. To simplify, two container cannot listen to same port, in same pod.

So in order to two nginx container within same pod, you need to run them on different port. One nginx can run on 80 and other on 81.

So we will run first-container with default nginx config and for second-container we will be running with below config.

• default.conf

server {
    listen       81;
    server_name  localhost;
    #charset koi8-r;
    #access_log  /var/log/nginx/host.access.log  main;

    location / {
    root   /usr/share/nginx/html;
    index  index.html index.htm;
    }

    #error_page  404              /404.html;

    # redirect server error pages to the static page /50x.html
    #
    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
    root   /usr/share/nginx/html;
    }

    # proxy the PHP scripts to Apache listening on 127.0.0.1:80
    #
    #location ~ \.php$ {
    #    proxy_pass   http://127.0.0.1;
    #}

    # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
    #
    #location ~ \.php$ {
    #    root           html;
    #    fastcgi_pass   127.0.0.1:9000;
    #    fastcgi_index  index.php;
    #    fastcgi_param  SCRIPT_FILENAME  /scripts$fastcgi_script_name;
    #    include        fastcgi_params;
    #}

    # deny access to .htaccess files, if Apache's document root
    # concurs with nginx's one
    #
    #location ~ /\.ht {
    #    deny  all;
    #}
}

• Create a configmap from this default.conf

kubectl create configmap nginx-conf --from-file default.conf

• Create a pod as following.

apiVersion: v1
kind: Pod
metadata:
  name: two-containers
spec:
  restartPolicy: Never
  volumes:
  - name: config
    configMap:
      name: nginx-conf
  containers:
  - name: first-container
    image: nginx
    ports:
    - containerPort: 80
  - name: second-container
    image: nginx
    ports:
    - containerPort: 81
    volumeMounts:
    - name: config
      mountPath: /etc/nginx/conf.d

• Deploy the pod.

• Now exec into the pod and try to ping on localhost:80 and localhost:81 it will work. Let me know, if you need any more help in it.