Custom nginx.conf from ConfigMap in Kubernetes

Question

I have Kubernetes set up in a home lab and I am able to get a vanilla implementation of nginx running from a deployment.

The next step is to have a custom nginx.conf file for the configuration of nginx. For this, I am using a ConfigMap.

When I do this, I no longer receive the nginx index page when I navigate to http://192.168.1.10:30008 (my local ip address for the node the nginx server is running on). If I try to use the ConfigMap, I receive the nginx 404 page/message.

I am not able to see what I am doing incorrectly here. Any direction would be much appreciated.

nginx-deploy.yaml

apiVersion: v1
kind: ConfigMap
metadata:
  name: nginx-conf
data:
  nginx.conf: |
    user nginx;
    worker_processes  1;
    events {
      worker_connections  10240;
    }
    http {
      server {
          listen       80;
          server_name  localhost;
          location / {
            root   html;
            index  index.html index.htm;
        }
      }
    }

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 1
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx
        ports:
        - containerPort: 80
        volumeMounts:
            - name: nginx-conf
              mountPath: /etc/nginx/nginx.conf
              subPath: nginx.conf
              readOnly: true
      volumes:
      - name: nginx-conf
        configMap:
          name: nginx-conf
          items:
            - key: nginx.conf
              path: nginx.conf

---
apiVersion: v1
kind: Service
metadata:
  name: nginx
spec:
  type: NodePort
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
    nodePort: 30008
  selector:
    app: nginx 

Answer 1

Nothing complex, it's the root directory in the nginx.conf is not defined correctly.

Checking the logs with kubectl logs <<podname>> -n <<namespace>> gives why the 404 error is happening for a particular request.

xxx.xxx.xxx.xxx - - [02/Oct/2020:22:26:57 +0000] "GET / HTTP/1.1" 404 153 "-" "curl/7.58.0" 2020/10/02 22:26:57 [error] 28#28: *1 "/etc/nginx/html/index.html" is not found (2: No such file or directory), client: xxx.xxx.xxx.xxx, server: localhost, request: "GET / HTTP/1.1", host: "xxx.xxx.xxx.xxx"

It's because of location inside your configmap is referring to wrong directory as root root html.

Change the location to a directory which has index.html will fix the issue. Here is the working configmap with root /usr/share/nginx/html. However this could be manipulated as you want, but we need to make sure files exist in the directory.

apiVersion: v1
kind: ConfigMap
metadata:
  name: nginx-conf
data:
  nginx.conf: |
    user nginx;
    worker_processes  1;
    events {
      worker_connections  10240;
    }
    http {
      server {
          listen       80;
          server_name  localhost;
          location / {
            root   /usr/share/nginx/html; #Change this line
            index  index.html index.htm;
        }
      }
    }