Conusume API from a client docker container to the server container - docker

Question

I have two different projects running on different docker containsers. Below the two YML files:
FILE webserver-api/docker-compose.yml
version: "3.1"
services:
webserver:
image: nginx:alpine
container_name: webserver-api
working_dir: /application
volumes:
- .:/application
- ./docker/nginx/nginx.conf:/etc/nginx/conf.d/default.conf
ports:
- "8005:80"
FILE client-app/docker-compose.yml
version: '3'
services:
web:
container_name: client-app
build:
context: ./
dockerfile: deploy/web.docker
volumes:
- ./:/var/www
ports:
- "8010:80"
links:
- app
app: [...]
database: [...]
From the client-app I would like to call the webserver-api.
When I'm trying to consume the API from webserver-api I'm getting the message "cURL error connection refused" or timeout error.
For example
$response = file_get_contents('http:/localhost:8005/api/test');
I tried also to replace the localhost with the IP of the webserver-api container like this:
$response = file_get_contents('http://172.25.0.2:8005/api/test');
But still I get a timeout connection error.
Which is the correct URL of the server container to call form the client container? Or how to set the host URL?
Thanks a lot for the help and time.

Answer 1

You need create a network first. Then use this network for both your client and server docker compose. Otherwise the network is isolated.
Another approach is expose the port of server to localhost and connect to localhost from client side.

Answer 2

As per the docker-compose documentation
By default Compose sets up a single network for your app. Each container for a service joins the default network and is both reachable by other containers on that network, and discoverable by them at a hostname identical to the container name.
So ideally if your service are interdependent you should put them in a single compose file. In that case you could have accessed your service directly by name and container port
http://webserver/api/test
But since they are in separate compose file, you can access the service via host mapped port
$response = file_get_contents('http://localhost:8005/api/test');
it should also work.
To debug you can check
If port binding to 8005 is happening on your host.
The endpoint specified is correct and accessible from host.

Answer 3

Finally I figured it out.
By default docker creates a network called (in my case) webserver-api_default where webserver-api is the name of the folder that contains the YML file [projectname]_default.
On the client-app/docker-compose.yml of the client I had to specify which network to join:
version: '3'
networks:
default:
external:
name: webserver-api_default
web:
container_name: client-app
build:
context: ./
dockerfile: deploy/web.docker
volumes:
- ./:/var/www
ports:
- "8010:80"
links:
- app
app: [...]
database: [...]
And from the client container I have to make the call to the URL:
$response = file_get_contents('http://webserver-api:8005/api/test');
Where webserver-api is the name of the server container and not the name of the network.
https://docs.docker.com/compose/networking/