How to run any commands in docker volumes? - docker

Question

After couple of days testing and working on docker (i am in general trying to migrate from vagrant to docker) i encountered a huge problem which i am not sure how or where to fix it.
docker-compose.yml
version: "3"
services:
server:
build: .
volumes:
- ./:/var/www/dev
links:
- database_dev
- database_testing
- database_dev_2
- mail
- redis
ports:
- "80:8080"
tty: true
#the rest are only images of database redis and mailhog with ports
Dockerfile
example_1
FROM ubuntu:latest
LABEL Yamen Nassif
SHELL ["/bin/bash", "-c"]
RUN apt-get install vim mc net-tools iputils-ping zip curl git -y
RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer
RUN cd /var/www/dev
RUN composer install
Dockerfile
example_2
....
RUN apt-get install apache2 openssl php7.2 php7.2-common libapache2-mod-php7.2 php7.2-fpm php7.2-mysql php7.2-curl php7.2-dom php7.2-zip php7.2-gd php7.2-json php7.2-opcache php7.2-xml php7.2-cli php7.2-intl php7.2-mbstring php7.2-redis -y
# basically 2 files with just rooting to /var/www/dev
COPY docker/config/vhosts /etc/apache2/sites-available/
RUN service apache2 restart
....
now the example_1 composer.json file/directory not found
and example_2 apache will says the root dir is not found
file/directory = /var/www/dev
i guess its because its a volume and it wont be up until the container is fully up because if i launch the container without the prev commands which will lead to an error i can then login to the container and execute the commands from command line without anyerror
HOW TO FIX THIS ?

Answer 1

In your first Dockerfile, use the COPY directive to copy your application into the image before you do things like RUN composer install. It'd look something like
FROM php:7.0-cli
COPY . /usr/src/app
WORKDIR /usr/src/app
RUN composer install
(cribbed from the php image documentation; that image may not have composer preinstalled).
In both Dockerfiles, remember that each RUN command creates a new empty container, runs its command, and cleans up after itself. That means commands like RUN cd ... have no effect, and you can't start a service in the background in one RUN command and have it available later; it will get stopped before the Dockerfile moves on to the next line.
In the second Dockerfile, commands like service or systemctl or initctl just don't work in Docker and you shouldn't try to use them. Standard practice is to start the server process as a foreground process when the container launches via a default CMD directive. The flip side of this is that, since the server won't start until docker run time, your volume will be available at that point. I might RUN mkdir in the Dockerfile just to be sure it exists.

Answer 2

The problem seems the execution order. At image build time /var/www/dev is available. When you start a container from that image the container /var/www/dev is overwritten with your local mount.
If you need no access from your host, the you can simple skip the extra volume.
In case you want use it in other containers to, the you should work with symlinks.