A method to run multiple applications in single App Service

[Guest yorkzhang]

Sometimes we want to have applications developed in various languages in one App Service. There is a solution - Docker Compose. However, it is still in Preview status, so it is not recommended to use it in Production environment. There are also some limitations. In this article, I would like to use a sample app service to introduce a method to do the same thing by using nginx and custom docker container.

 

 

 

Note

 

The current method does not obey the recommendation of Docker that a docker container should host only one service, and we actually recommend customers use Azure Container App for hosting multiple applications.

 

 

 

Design

 

We will create a Docker container to have nginx installed and use it as a reverse proxy to redirect the request from external to different applications.

 

 

 

 

The above picture shows that the request comes from outside firstly arrived at the nginx service at port 8082 in the container. If the request url is ending with /php/, the request will be direct to the Apache server listening 80 port. Otherwise, the request will be processed in node express server.

 

 

 

Implementation

 

Firstly, we need to create a Docker image. I use below Dockerfile for creating the image:

 

 

 

 

 

FROM oberd/php-8.0-apache

 

RUN apt-get update && apt-get install -y nodejs npm

 

RUN apt-get -y install nginx

 

RUN echo "ServerName localhost:80" >> /etc/apache2/apache2.conf

 

COPY nginx.conf /etc/nginx/nginx.conf

 

COPY default /etc/nginx/sites-enabled/default

 

#WORKDIR is /var/www/html

 

COPY . /var/www/html/

 

EXPOSE 8082

 

RUN chmod 777 /var/www/html/start.sh

 

RUN npm install

 

ENTRYPOINT ["/var/www/html/start.sh"]

 

 

 

 

 

Explanation:

- Use an Apache image container so I do not need to install Apache 8.0.

- Then install node.js, npm and nginx.

- "RUN echo "ServerName localhost:80" >> /etc/apache2/apache2.conf" will configure Apache server to use port 80 to recieve the request.

- Copy modified nginx.conf, defaut files to configure the nginx to use reverse proxy and expected port to receive request.

- Change the start.sh file permission to make sure it can run properly.

- At the end of the Dockerfile, it will launch start.sh file.

Below is the modified part of the nginx.conf:

 

 

 

 

 

server{

 

listen 8082;

 

server_name _;

###

if request is end with /php/..., the request will be directed to 80 port in 127.0.0.1.

###

location /php{

 

proxy_pass http://127.0.0.1:80/;

 

}

###

if request is end with /..., the request will be directed to 3000 port in 127.0.0.1.

###

location /{

 

proxy_pass http://127.0.0.1:3000/;

 

}

 

}

 

 

 

 

 

Below is the modified default file which change the nginx default port to 8081 to avoid port conflicts with Apache which uses port 80.

 

 

 

 

 

##

 

# You should look at the following URL's in order to grasp a solid understanding

 

# of Nginx configuration files in order to fully unleash the power of Nginx.

 

# Pitfalls and Common Mistakes | NGINX

 

# wiki.nginx.org Managed WordPress Site – Just another WordPress site

 

# Getting Started | NGINX

 

#

 

# Generally, you will want to move this file somewhere, and start with a clean

 

# file but keep this around for reference. Or just disable in sites-enabled.

 

#

 

# Please see /usr/share/doc/nginx-doc/examples/ for more detailed examples.

 

##

 

# Default server configuration

 

#

 

server {

 

listen 8081 default_server;

 

listen [::]:8081 default_server;

 

...........

 

 

 

 

 

Below is the start.sh file which is created to start the related application and service. Explanations are in comments.

 

 

 

#!/bin/bash

 

#restrat nginx to ensure it will use the replaced & modified configuration files

service nginx restart

 

#restrat Apache service to ensure it will use the modified configuraton file

service apache2 restart

 

#start the express web server

node express_demo.js

 

 

 

 

In the example, I simply use php.info file as a PHP application and express_demo.js as a node application. Please refer to below public GitHub repository for the whole project:

 

yorkzhang/dockernodephp (github.com)

 

 

After you create the docker image and use app service to pull it from your docker repository. You need to make sure that a application setting WEBSITES_PORT is set to 8082 as your nginx is listening to 8082.

 

 

 

This example is just for your reference. Actually, to host a PHP application, you do not need to have a separated Apache service but just need to use the existing nginx web server. You may refer to below document for setting this:

PHP FastCGI Example | NGINX

 

 

 

However, purely using Nginx as a reverse proxy is totally OK as you can have flexibility to choose other applications' web servers.

 

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