Cannot start apache automatically with docker

Question

I made a simple custom docker setup for php development. So far everything works as expected. The only thing that I cannot figure out is why apache2 does not start automatically.

Here is my dockerfile:

FROM ubuntu:latest
RUN apt-get update && apt-get install -y apache2 php libapache2-mod-php php-mcrypt php-mysql php-cli php-curl php-xml php-intl php-mbstring git vim composer curl

COPY . /var/www/example
COPY vhost.conf /etc/apache2/sites-available/example.conf

RUN a2ensite example
RUN chown -R www-data:www-data /var/www/example/logs
RUN service apache2 restart

And here is my docker-compose.yml:

version: '2'
services:
  app:
    build:
      context: .
      dockerfile: Dockerfile
    image: myexampleapp
    ports:
        - 8080:80
    tty: true

And here is the output docker-compose up command:

me@mydell:~/workspace/mydockercompose$ docker-compose up -d --build
Creating network "mydockercompose_default" with the default driver
Building app
Step 1/7 : FROM ubuntu:latest
 ---> f975c5035748
Step 2/7 : RUN apt-get update && apt-get install -y apache2 php libapache2-mod-php php-mcrypt php-mysql php-cli php-curl php-xml php-intl php-mbstring git vim composer curl
 ---> Using cache
 ---> 148c3a9d928a
Step 3/7 : COPY . /var/www/example
 ---> 1fbc1dbacf1e
Step 4/7 : COPY vhost.conf /etc/apache2/sites-available/example.conf
 ---> 9c08947b09e9
Step 5/7 : RUN a2ensite example
 ---> Running in 1ef64defe747
Enabling site example.
To activate the new configuration, you need to run:
  service apache2 reload
Removing intermediate container 1ef64defe747
 ---> ca1c8e7e80fc
Step 6/7 : RUN chown -R www-data:www-data /var/www/example/logs
 ---> Running in 57b0214be7a0
Removing intermediate container 57b0214be7a0
 ---> b3b270a36bf4
Step 7/7 : RUN service apache2 restart
 ---> Running in 09d2b1d3bd91
 * Restarting Apache httpd web server apache2
AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 172.17.0.2. Set the 'ServerName' directive globally to suppress this message
   ...done.
Removing intermediate container 09d2b1d3bd91
 ---> 19fa9a90f9de
Successfully built 19fa9a90f9de
Successfully tagged myexampleapp:latest
Creating mydockercompose_app_1

It shows clearly that apache was restarted successfully. However it actually does not:

me@mydell:~/workspace/mydockercompose$ docker exec -i -t 20add8ad9895 service apache2 status
 * apache2 is not running

I am new to docker, so all suggestions (even if they are not answering this specific question) to improve what I am doing so far are welcome.

Thanks

Answer 1

Docker services have to be running in the foreground. In your Dockerfile, RUN service apache2 restart will start apache as background process. Hence the container will exit.

To run apache in the foreground, add the following to the Dockerfile.

CMD ["/usr/sbin/apachectl", "-D", "FOREGROUND"]

FROM ubuntu:latest
RUN apt-get update && apt-get install -y apache2 php libapache2-mod-php php-mcrypt php-mysql php-cli php-curl php-xml php-intl php-mbstring git vim composer curl

COPY . /var/www/example
COPY vhost.conf /etc/apache2/sites-available/example.conf

RUN a2ensite example
RUN chown -R www-data:www-data /var/www/example/logs
CMD ["/usr/sbin/apachectl", "-D", "FOREGROUND"]