docker-compose.yaml.md

docker-compose.yaml

docker-compose sits ontop of docker, used to manage multi container apps this one has three containers, called services in the yaml, php which is the app+php+apache, db which runs mysql and phpmyadmin which runs phpmyadmin

• docker-compose default file docker-compose.yaml
• docker-compose default file docker-compose.yml
• docker default file Dockerfile

(see https://docs.docker.com/compose/compose-file/)

Note: the indentation determines what goes with what

Note: this is describing docker-compose.yaml

docker-compose.yaml yaml only, no comments

version: "3.7"

services:
  php:
    build: ./php
    volumes: 
        - ./jeffstickyphp/:/var/www/html
        - /var/log:/var/log
    networks:
      - backend
      - frontend
    ports:
        - '8700:80'
    environment:
        - XYZ="this is an example"
    depends_on:
        - db
  db:
    image: mysql:latest
    command: --innodb_use_native_aio=0

    environment:
     MYSQL_DATABASE: assignment2
     MYSQL_USER: student
     MYSQL_PASSWORD: secret
     MYSQL_ROOT_PASSWORD: educate3
    networks:
      - backend
    volumes:
      - ./dbsetup:/docker-entrypoint-initdb.d
      - persistent:/var/lib/mysql
    ports:
        - "3306"
  phpmyadmin:
    links:
      - db:db
    image: phpmyadmin/phpmyadmin
    environment:
     MYSQL_USER: student
     MYSQL_PASSWORD: secret
     MYSQL_ROOT_PASSWORD: educate3
    networks:
     - backend
     - frontend
    ports:
        - "8701:80"
    depends_on:
        - db
volumes:
    persistent:
networks:
  frontend:
  backend:

docker-compose.yaml same yaml as above but with markdown explanations

version: the docker-compose version with which the file corresponds

version: "3.7"

services:

all services (containers) are indented under this

• https://docs.docker.com/compose/compose-file/#services

php: container / service name (host name on network)

all containers configs are indented under this, the name used is pingable on the container network. For example to use the db container as the host from the php container configure db as the server_name. see config.ini for app runtime config.

Each named service resolve internally to the correct ip address depending on container networking.

services:
  php:

build: location of the Dockerfile

only needed if we are building our own in this case the app is deployed on a container

• https://docs.docker.com/compose/compose-file/#build

    build: ./php

volumes: mapping local to container

volumes is a complex subject see the ^ compose file reference, here we are "developing" the app so the app is run from the localhost ./jeffstickyphp/:/var/www/html and we have the log files written to the localhost /var/log:/var/log https://docs.docker.com/compose/compose-file/#volume-configuration-reference

    volumes: 
        - ./jeffstickyphp/:/var/www/html
        - /var/log:/var/log

networks: configure the container, internal network

networks are also a complex subject, avoid links but you may see them

• legacy feature https://docs.docker.com/network/links/
• should use https://docs.docker.com/network/bridge/ This container is outward facing (website) and internal for access to the db container.

    networks:
      - backend
      - frontend

ports: forward 80 from container to 8700 host

If you are using single containers this is done in the run statement yaml sits on top of docker, most docker commands with docker-compose

• https://docs.docker.com/compose/compose-file/#ports

    ports:
        - '8700:80'

depends_on: internal dependecies for order of ops

means anything under here must be built before this service

• https://docs.docker.com/compose/compose-file/#depends_on

    depends_on:
        - db

db: container / service name (host name on network)

all containers configs are indented under this, the name used is pingable on the container network. For example to use the db container as the host from the php container

no build needed, using pre built image

image: the image to pull from the registry (docker hub in this case)

This is the image, you can find environment vars & other runtime information here

• https://hub.docker.com/_/mysql/

  db:
    image: mysql:latest

command the command(s) to run on container launch

this one is needed due to an error in mysql v8+ see the yaml for info

• https://docs.docker.com/compose/compose-file/#command

    command: --innodb_use_native_aio=0

environment: variables for use by the conainer

in this case we are using a base image and setting it up for our app, so the vars are specific to the image

• https://docs.docker.com/compose/compose-file/#environment

    environment:
     MYSQL_DATABASE: assignment2
     MYSQL_USER: student
     MYSQL_PASSWORD: secret
     MYSQL_ROOT_PASSWORD: educate3

networks: configure the container, internal network

networks are also a complex subject, avoid links but you may see them

• legacy feature https://docs.docker.com/network/links/
• should use https://docs.docker.com/network/bridge/ Note the database is only used internally, between containers, so only need the backend

    networks:
      - backend

volumes: mapping local to container

volumes is a complex subject see the ^ compose file reference, here we are using a docker startup directory, everything in here that is a script (.sh or .sql) will be run on startup/engry to the container
./dbsetup:/docker-entrypoint-initdb.d I am uncertaine whether it is better to copy the files over, or to mount a volume, need to understand volumes better

we also have the database o persistent storrage, containers are ephemeral so if we want data to persist we must do this persistent:/var/lib/mysql

    volumes:
      - ./dbsetup:/docker-entrypoint-initdb.d
      - persistent:/var/lib/mysql

ports: no forwarding needed, tested, only need the port internally to the container network

If you are using single containers this is done in the EXPOSE statement yaml sits on top of docker, most docker commands with docker-compose

    ports:
        - "3306"

phpmyadmin: container / service name (host name on network)

Used to look at and manage db for testing only no build/Dockerfile needed, using pre built image

image: the image to pull from the registry (docker hub in this case)

This is the image, you can find environment vars & other runtime information here

• https://hub.docker.com/u/phpmyadmin/

  phpmyadmin:
    image: phpmyadmin/phpmyadmin

environment: variables for use by the conainer

in this case we are using a base image and setting it up for our app, so the vars are specific to the image

• https://docs.docker.com/compose/compose-file/#environment

    environment:
     MYSQL_USER: student
     MYSQL_PASSWORD: secret
     MYSQL_ROOT_PASSWORD: educate3

networks: configure the container, internal network

networks are also a complex subject, avoid links but you may see them

• legacy feature https://docs.docker.com/network/links/
• should use https://docs.docker.com/network/bridge/ This container is outward facing (website) and internal for access to the db container. I think the links is needed for that, not sure if the db overrides it todo: test this assumption.

    networks:
     - backend
     - frontend
    links:
       - db:db

ports: forward 80 from container to 8700 host

If you are using single containers this is done in the run statement yaml sits on top of docker, most docker commands with docker-compose

• https://docs.docker.com/compose/compose-file/#ports

    ports:
        - "8701:80"

depends_on: internal dependecies for order of ops

means anything under here must be built before this service

• https://docs.docker.com/compose/compose-file/#depends_on

    depends_on:
        - db

global config values

volumes:
    persistent:
networks:
  frontend:
  backend: