How to define build-args in docker-compose?

Question

I have the following docker-compose file

version: \'3\'
services:
    node1:
            build: node1
            image: node1
            container_name: n         


        

Answer 1

You can define your args with your build command of docker-compose.

Example Dockerfile:

FROM nginx:1.13

RUN apt-get -y update && apt-get install -y \
    apache2-utils && \
    rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

ARG username
ARG password

RUN htpasswd -bc /etc/nginx/.htpasswd $username $password

docker-compose file:

version: '3'
services:
  node1:
     build: ./dir

The ./dir contains the Dockerfile and I build with this command:

docker-compose build --build-arg username="my-user" --build-arg password="my-pass"

I see already:

Step 5/5 : RUN htpasswd -bc /etc/nginx/.htpasswd $username $password
 ---> Running in 80735195e35d
Adding password for user my-user
 ---> c52c92556825

I bring my stack up:

docker-compose up -d

Now I can check inside the nginx container and my username and (encrypted) password are there:

docker@default:~/test$ docker exec -it test_node1_1 bash
root@208e4d75e2bd:/# cat /etc/nginx/.htpasswd
my-user:$apr1$qg4I/5RO$KMaOPvjbnKdZH37z2WYfe1

Using this method your able to pass build args to your docker-compose stack.