Archivi del mese: Luglio 2023

Docker Container with Java and MySql

We need now a container that should be able to execute a spring boot application (jar) and a linked mysql db.

For this we need a docker compose file and a Dockerfile

Dockerfile for Java

FROM openjdk:11
COPY ./app ./app
CMD java -Djava.net.preferIPv4Stack=true -jar /app/JavApp.war

In this example we use the java version 11 (openjdk)

Then we copy all file (actually only the jar file) from our local folder (./app) to the container folder (/app)

Finally we execute the command line to execute the jar file, adding also some java parameter

Docker compose for java and mysql

version: "3.8"
services:
  mysqldb:
    image: mysql
    environment:
      MYSQL_ROOT_PASSWORD: thisIsTheRootPwd
      MYSQL_DATABASE: fconsulting
      MYSQL_USER: fconsuser
      MYSQL_PASSWORD: fconspassword
    ports:
      - "3306:3306"
    volumes:
      - ./dbdata:/var/lib/mysql
  app:
    depends_on:
      - mysqldb
    build: 
      context: .
      dockerfile: Dockerfile
    ports:
      - 8081:8080
    environment:
      JDBC_CONNECTION_STRING: 'jdbc:mysql://mysqldb:3306/fconsulting?allowPublicKeyRetrieval=true&useSSL=false'
      JDBC_PWD: 'fconspassword'
      JDBC_USER: 'fconsuser'
      ClientId: '...'
      ClientSecret: '...'
      mongourl: 'mongodb+srv://...'
    stdin_open: true
    tty: true

In the same folder of Dockerfile we have our docker compose yaml file. The most intersting part is the environment field in which we specify all the system props needed by our java application

Container with Apache, PHP and MySql

Create a new file named docker-composer.yml

version: "3.8"
services:
  php:
    container_name: php8apache
    image: php:8.1-apache
    volumes:
      - ./html:/var/www/html
    ports:
      - 8080:80
 

version: “3.8” is the docker compose version to use

services: is the section where to specify all the pieces of our composition

php: is the service name, you can name it as you want

container_name is an optional filed in which you specify the name of this service container

image: php:8.1-apache, means that our service will be implemented starting from php image and version 8.1-apache

volumes: – ./html:/var/www/html in this case we are associating our local folder ./html to the container folder /var/www/html

ports: – 8080:80 we are binding the local port 8080 to the container port 80

To execute the container with docker compose let’s type the following code:

docker-compose up -d

After it finishes to download artifacts we can try to reach the address http://localhost:8080

Try to personalize the index.php page in the folder ./html adding a index.php file

Add MySql service

At the bottom of our docker yaml file we should add a new mysql service:

version: "3.8"
services:
  php:
    container_name: php8apache
    image: php:8.1-apache
    volumes:
      - ./html:/var/www/html
    ports:
      - 8080:80
    depends_on: 
      - mysql
  mysql:
    image: mysql
    environment:
      MYSQL_ROOT_PASSWORD: thisIsTheRootPwd
      MYSQL_DATABASE: fconsulting
      MYSQL_USER: fconsuser
      MYSQL_PASSWORD: fconspassword
    ports:
      - "9906:3306"

We added the mysql section defining environment parameters and ports to map

The image used is mysql (:latest)

Moreover we added also the depend_on parameter in the php section, because our php service depends on the mysql service to work.

But that is not enough, because, like we would do in a normal environment, we need to install in our container also the php library to make php work with mysql.

To do so we need a Dockerfile in which we specify the php-apache version + the libraries we need.

So create a Dockerfile in the same folder of docker-compose.yaml (actually you can create this docker file wherever you want) and put this code:

FROM php:8.1-apache
RUN docker-php-ext-install mysqli && docker-php-ext-enable mysqli
RUN apt-get update && apt-get upgrade -y

FROM php:8.1-apache is the image that we already specified in the docker-compose file

RUN … are the linux commands to download libraries and download updates

Because we are using a Dockerfile to download the image we should update the docker compose file removing, from php section, the “imagine” section replacing it with the docker section:

version: "3.8"
services:
  php:
    container_name: php8apache
    build: 
      context: .
      dockerfile: Dockerfile
    volumes:
      - ./html:/var/www/html
    ports:
      - 8080:80
    depends_on: 
      - mysql
  mysql:
    image: mysql
    environment:
      MYSQL_ROOT_PASSWORD: thisIsTheRootPwd
      MYSQL_DATABASE: fconsulting
      MYSQL_USER: fconsuser
      MYSQL_PASSWORD: fconspassword
    ports:
      - "9906:3306"

in the build section we specify from which dockerfile to read the imagine and eventually all the other instruction to build our layer.

Now it’s ok.

Add PhpMyAdmin

What is MySql without PhpMyAdmin? Nothing! 😛

So let’s add PhP My Admin to the docker compose:

version: "3.8"
services:
  php:
    container_name: php8apache
    build: 
      context: .
      dockerfile: Dockerfile
    volumes:
      - ./html:/var/www/html
    ports:
      - 8080:80
    depends_on: 
      - mysql
  mysql:
    image: mysql
    environment:
      MYSQL_ROOT_PASSWORD: thisIsTheRootPwd
      MYSQL_DATABASE: fconsulting
      MYSQL_USER: fconsuser
      MYSQL_PASSWORD: fconspassword
    ports:
      - "9906:3306"
  phpmyadmin:
    image: phpmyadmin
    ports:
        - '8090:80'
    environment:
        PMA_HOST: mysql
    depends_on:
        - mysql

imagine: phpmyadmin (:latest) is the original phpmyadmin imagine from docker hub

ports: – ‘8090:80’, I chose 8090 but feel free to use whatever port you want

environment: PMA_HOST, mysql it is the reference to which db to use with phpmyadmin

depends_on: – mysql, this service depends on mysql server

To access with phpmyadmin use root as user and the MYSQL_ROOT_PASSWORD as password.

That’s it

Container

A Container ia basically an Image that is executed.

To execute a container you can use the following command:

docker container run [OPTIONS] <imagename> [COMMAND] [ARG]

where

[OPTIONS], is the flags used to execute the command

[COMMAND] is the instruction that you could execute the container if we don’t like the default command inside the image

[ARG] is the param that we can pass to the container

What does it happen when we launch a container?

First of all Docker tries to find the image locally. If it doesn’t find it it serach into Docker hub.

If we don’t specify a tag the “latest” will be used.

And finally we have our container!

Docker will assign a virtual IP in the private network of the container. After that the binding will be executed

Example

To see all important aspects let’s instantiate a nginx container sing 1.19.5-alpine image

P.S.: Alpine is a Linux distribuition

docker container run -it --rm -d -p 8080:80 --name web nginx:1.19.5-alpine

where:

-it, is a combination of -i and -t, where -i means interact with the standard input and -t interact with the container with a tty interface

-rm, the container will be automatically deleted once terminated

-d, once instantiated the execution will be in background mode

-p 8080:80, the container port 80 will be linked to the 8080 port of the host

–name web, give the “web’ name to the container

once executed you can reach the server at the address http://localhost:8080

Add a volume

In order to associate a local volume (folder) to a container folder we need to add a param in our command line which map our local folder to container folde:

-v /your/local/folder:/container/folder

So the new complete command line will be:

docker container run -it --rm -d -p 8080:80 --name web -v /your/local/folder:/container/folder nginx:1.19.5-alpine

In our specific example, we would point the container folder /usr/share/nginx/html, in which there is the html folder for nginx to our local, previously created, folder /Users/xxx/nginx/html, to override that specifi folder

docker container run -it --rm -d -p 8080:80 --name web -v /Users/xxx/nginx/html:/usr/share/nginx/html nginx:1.19.5-alpine