How to Correctly Link PHP-Fpm and Nginx Docker Containers

How to correctly link php-fpm and Nginx Docker containers?

Don't hardcode ip of containers in nginx config, docker link adds the hostname of the linked machine to the hosts file of the container and you should be able to ping by hostname.

EDIT: Docker 1.9 Networking no longer requires you to link containers, when multiple containers are connected to the same network, their hosts file will be updated so they can reach each other by hostname.

Every time a docker container spins up from an image (even stop/start-ing an existing container) the containers get new ip's assigned by the docker host. These ip's are not in the same subnet as your actual machines.

see docker linking docs (this is what compose uses in the background)

but more clearly explained in the docker-compose docs on links & expose

links

links:
 - db
 - db:database
 - redis

An entry with the alias' name will be created in /etc/hosts inside containers for this service, e.g:

172.17.2.186  db
172.17.2.186  database
172.17.2.187  redis

expose

Expose ports without publishing them to the host machine - they'll only be accessible to linked services. Only the internal port can be specified.

and if you set up your project to get the ports + other credentials through environment variables, links automatically set a bunch of system variables:

To see what environment variables are available to a service, run docker-compose run SERVICE env.

name_PORT

Full URL, e.g. DB_PORT=tcp://172.17.0.5:5432

name_PORT_num_protocol

Full URL, e.g. DB_PORT_5432_TCP=tcp://172.17.0.5:5432

name_PORT_num_protocol_ADDR

Container's IP address, e.g. DB_PORT_5432_TCP_ADDR=172.17.0.5

name_PORT_num_protocol_PORT

Exposed port number, e.g. DB_PORT_5432_TCP_PORT=5432

name_PORT_num_protocol_PROTO

Protocol (tcp or udp), e.g. DB_PORT_5432_TCP_PROTO=tcp

name_NAME

Fully qualified container name, e.g. DB_1_NAME=/myapp_web_1/myapp_db_1

When running Nginx + PHP-FPM in two different containers, can that configuration ever work without sharing a code volume?

I've never seen a setup where Nginx and PHP were running in separate ECS tasks that scaled independently. I've always seen it where they are both running in the same ECS task, with a shared folder.

I wouldn't worry too much about this being "wasteful". You're adding a tiny amount of CPU usage to each Fargate ECS task by adding Nginx to each task. I would focus more on the fact that you are keeping latency as low as possible by running them both in the same task, so Nginx can pass requests to PHP over localhost.

Docker Nginx connect to PHP-FPM on private docker network

Ok, so my above question IS the correct answer. I was just having trouble with the order of starting containers (I also have reverse proxies and others in play, it got a bit confusing).

For anyone who wants to connect docker nginx to a docker php, this is correct setup:

My php container command (run first):

docker run -d \
    --name php7 \
    -v /php7:/usr/local/etc \
    -v /www_data:/www \
    --network=priv-bridge-net \
    -p 9000:9000 \
    php:7.0.24-fpm

My nginx command:

docker run -d \
    --name nginx \
    -v /nginx_conf:/etc/nginx \
    -v /www_data:/usr/share/nginx/html \
    --network=priv-bridge-net \
    nginx:1.13.5

My nginx config:

server {
    index index.php index.html;
    server_name test;
    error_log  /var/log/nginx/error.log;
    access_log /var/log/nginx/access.log;
    root /usr/share/nginx/html;

    location ~ \.php$ {
        try_files $uri =404;
        fastcgi_split_path_info ^(.+\.php)(/.+)$;
        fastcgi_pass php7:9000;
        fastcgi_index index.php;
        include fastcgi_params;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        fastcgi_param PATH_INFO $fastcgi_path_info;
    }
}

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