docker run phpmyadmin inside alpine container

Question

I discovered docker last week and am playing around withit for a decent time. Now I want to deploy a Website inside a Container. The Website is already finished and I got all the files on my host system. It needs php, java, tomcat and - and here is the problem - a mysql-db.

So I created a Dockerfile, using alpine:latest as base image and after that installing the above named applications one by one.

FROM alpine:latest

ENV http_proxy http://not_important/
RUN apk update
RUN apk --no-cache --quiet add openjdk8
RUN apk --no-cache --quiet add nano
RUN apk --no-cache --quiet add php7
RUN apk --no-cache --quiet add mysql
RUN apk --no-cache --quiet add phpmyadmin

RUN mkdir -p /usr/local/tomcat/
COPY apache-tomcat-9.0.4.tar.gz /usr/local/tomcat/

RUN cd /usr/local/tomcat/ && tar xzf /usr/local/tomcat/apache-tomcat-9.0.4.tar.gz
RUN mv /usr/local/tomcat/apache-tomcat-9.0.4/* /usr/local/tomcat
RUN rm -r /usr/local/tomcat/apache-tomcat-9.0.4
RUN rm -r /usr/local/tomcat/apache-tomcat-9.0.4.tar.gz

CMD ["/usr/local/tomcat/bin/catalina.sh", "run"]

But now, I dont rly know how to finish my work. How am I able to start the mysql-db and access it with phpmyadmin?

I run the container with the following command:

docker run --name alpine_custom -dit -p 30000:8080 -p31000:80 alpine:custom

The tomcat is running on port 30000 without a problem and I want phpmyadmin to be accessable over port 31000. I do have a working MySQL-DB on my Host and manage it with phpmyadmin (meaning, there are two containers, the phpmyadmin container is linked with the database)...

Is it even possible to do it like I want it, or do I have to deploy a second container with a database which is linked with my alpine container (and a third one with phpmyadmin...)?

I am thankful for every answer, thank you in advance

Sincerely Telvanis :)

PS: I know, the Dockerfile isn't very good but i think its enough for my needs ^^

Answer 1

Try to avoid having it "all-in-one".

This is the idea behind Docker, to go from something "monolithic" to something which is separated to components. This approach gives you an advantage when you want to scale up/down your app, update specific components without rebuilding the whole app... etc.

Try to avoid the installation & configuration of every technology on your own

I remember myself trying to do so with MySQL. I spent much time and had no result. Ended up using the official image. The installation of a software inside docker might have tricky parts and not be the same with the installation one does in a VM. So, I would propose to start searching for the official images of the technologies that you are trying to put into use. Docker hub has plenty and most of them also provide guidelines on how to use/configure them. For example:

• https://hub.docker.com/r/phpmyadmin/phpmyadmin/
• https://hub.docker.com/_/mysql/
• https://hub.docker.com/_/openjdk/

...you get the idea.

Your running containers will have names. Docker offers a DNS mechanism so that your containers can connect to each other by using these names. For example if you have a container for your MySQL database named my_app_db listening on port 5000, configure the phpmyadmin container to connect there. An important notice here: don't try these on the default network, because it will not work. Define your own test-network.

Dealing with 3,4,5... or maybe more containers will make you type commands to build them, run them, start/stop them. Here is where docker-compose comes in and proves to be very handy. Within a docker-compose.yml file, you can define a "composition" of inter-connecting containers and handle them with single commands like docker-compose up, docker-compose down etc...

Working example:

comes from here, but is slightly modified...

docker-compose.yml file:

version: '2'

services:

  mysql:
    image: mysql:latest
    container_name: phpmyadmin_testing_mysql
    environment:
      - MYSQL_ROOT_PASSWORD=test123

  phpmyadmin:
    image: phpmyadmin/phpmyadmin:latest
    container_name: phpmyadmin_testing
    volumes:
      - /sessions
    ports:
      - 8090:80
    environment:
      - PMA_ARBITRARY=1
      - TESTSUITE_PASSWORD=test123
    depends_on:
      - mysql

To run, simply use docker-compose up. To connect, use:

• server: phpmyadmin_testing_mysql (the name of the MySQL container)
• username: root
• password: test123