Map http requests from nginx to docker - docker

Question

I have different versions of my web application running in Docker containers. And nginx is running on my host machine.
Is it possible to access the desired deployed version of my web application with the help of sub-domain such as v1.myapp.io, v2.myapp.io without reconfiguring and restarting the nginx?
I also want to access future versions in the same way?
Could anyone tell me if there is any way to achieve it?
Please consider me a newbie to Docker/nginx world.
Thanks in Advance.

Answer 1

Yes, although it can be done but its very difficult to achieve with docker only. kubernetes will make this very easy and everything like dns, service mapping is provided out of the box. I will include both docker and kubernetes approach:
Docker approach:
A first draft will look like this, use regex in nginx server_name and set the docker container names with a pattern. Create a /etc/hosts entry for different containers like:
172.16.0.1 v1.docker.container
172.16.0.2 v2.docker.container
And nginx server conf look like:
server {
listen 80;
server_name "~^(?<ns>[a-z]+.+)\.myapp\.io";
resolver 127.0.0.1:53 valid=30s;
# make sure $ns.docker.container is resolved to container IP
set $proxyserver "$ns.docker.container";
location / {
try_files $uri #clusterproxy;
}
location #clusterproxy {
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-IP $clientip;
proxy_set_header X-Forwarded-For $clientip;
proxy_set_header X-Real-IP $clientip;
proxy_set_header X-Forwarded-Host $host;
proxy_set_header X-FORWARDED-PROTO 80;
proxy_pass http://$proxyserver:80;
}
}
Kubernetes approach:
Create different service and deployment for different versions in a namespace. Lets say namespace is 'app-namespace'. Service names are self explanatory:
APP version v1: v1-app-service
APP version v2: v2-app-service
To make nginx more flexible you can add the service name as namespace to $proxyserver
Nginx rule:
server {
listen 80;
server_name "~^(?<version>[a-z]+.+)\.myapp\.io";
# you can replace this with kubernetes dns server IP
resolver 127.0.0.1:53 valid=30s;
# make sure $ns.docker.container is resolved to container IP
set $proxyserver "$version.app-namespace.svc.kubernetes";
location / {
try_files $uri #clusterproxy;
}
location #clusterproxy {
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-IP $clientip;
proxy_set_header X-Forwarded-For $clientip;
proxy_set_header X-Real-IP $clientip;
proxy_set_header X-Forwarded-Host $host;
proxy_set_header X-FORWARDED-PROTO 80;
proxy_pass http://$proxyserver:80;
}
}

Answer 2

I found another solution to this problem after digging a lot. It can be easily be done with Automated Nginx Reverse Proxy for Docker.
Once docker container for ngninx was up and running on my system.
I spun two docker containers of my webapp(diff versions) with the following command:
docker run -e VIRTUAL_HOST=v1.myapp.io --name versionOne -d myapp.io:v1
docker run -e VIRTUAL_HOST=v2.myapp.io --name versionTwo -d myapp.io:v2
and it worked out for me.
Additional notes:
1. I am using dnsmasq for handling all dns queries