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Basic level

It is very simple to setup a HTTP redirection in Rahti using a web server like nginx. We can redirect to basically any URL we want with very complex logics. For this tutorial, we will keep it simple and simply redirect to a different host, but keeping the path of the URL.

Setup a HTTP redirection in Rahti

Procedure

  1. Deploy an NGINX Image. Start by clicking the '+ Add' button on top right and select Container images option.

    Quick create

  2. For this exercise it is recommended to use bitnami/nginx

    bitnami/nginx

  3. Add a Route by going to Networking -> Routes and clicking Create Route. Use the URL that you want to redirect. If you visit the URL, you should see the "nginx welcome page"

    route

  4. Add a ConfigMap with a server redirection block. Go to Workloads > ConfigMaps, click in Create ConfigMap. The Name will be later used when mounting the ConfigMap. The Key will be the name of the file (e.g. nginx.conf), and the Value the content of the file. 

    #nginx.conf
server {
        listen 8080;
        server_name test.com;
        return 301 $scheme://test2.com$request_uri;
}

    In this example, test.com is the original URL, and test2.com is the one that the user will be redirected to.

  5. Mount the Configmap to the nginx deployment as a volume. Go to deployment and make the following additions in the YAML file.

    spec:
# [possibly other values]
  template:
#   [even more other values]
    spec:
      volumes:
        - name: nginx-conf
          configMap:
            name: nginx-conf
            defaultMode: 420
      containers:
        - name: nginx
#         [again, more values]
          volumeMounts:
            - name: nginx-conf
              mountPath: /opt/bitnami/nginx/conf/server_blocks

    In this example, nginx-conf is the name of configMap, nginx-config is the key and the ConfigMap has to be mounted in /opt/bitnami/nginx/conf/server_blocks/, other images may store the nginx configuration in different folders.

Precision required

The YAML above contains the additions needed to make this example work. However, the example does not contain any extra lines that you might have, and adding new ones requires a bit of attention.

If you feel adventurous or manually editing YAML tedious, it is possible to create ConfigMap and VolumeMount with an oc command. 

echo '#nginx.conf
server {
        listen 8080;
        server_name test.com;
        return 301 $scheme://test2.com$request_uri;
}' | oc create configmap nginx-conf --from-file=nginx.conf=/dev/stdin
You will need to replace the <deployment-name> with a valid value of your environment.

oc set volume deployment/<deployment-name> --add \
  --name=nginx-conf \
  --type=configmap \
  --configmap-name=nginx-conf \
  --mount-path=/opt/bitnami/nginx/conf/server_blocks \
  --containers=nginx

This tutorial does not handle oc command in detail but you can get started with another tutorial: Command line tool usage.

Add more host domains

If you need to redirect more than one host domain, you can use the same nginx, you just need to (1) add a new Route with the new host, and (2) add a new server block to the existing ConfigMap. In order for nginx to pick up the new configuration, you can delete the Pod or enter in the pod's terminal and run nginx -s reload.

Conclusion and more

Nginx is a powerful web server. You can use it also as a HTTP proxy and load balancer. For more information, please check the documentation at https://nginx.org/en/docs/.