6.7 KiB
Docker
To install PostgreSQL, Postgres Admin console, Redis and the test Web app, you would use docker-compose.
Install Docker
Download and install Docker for Mac : Docker Community Edition for Mac
Docker for Mac already includes Compose along with other Docker apps, so Mac users do not need to install Compose separately.
Run Docker compose
docker-compose up -d
Configure components
Looking at the docker-compose.yml file section by section:
PostgreSQL
PostgreSQL:
image: postgres:alpine
ports:
- 5432:5432
restart: always
env_file: .env
volumes:
- "$ROOT/postgresql:/var/lib/postgresql/data"
- ./setup/postgres/init.sql:/docker-entrypoint-initdb.d/init.sql
This sets PostgreSQL to use the Postgres:Alpine image. This is a version of the Postgres image built upon the Alpine Linux disk image, it is 5MB so makes for a slimmer image.
A 'friendly' name is set for the image, otherwise it will create the running image with a slightly cryptic name which appears to be based upon the current directory, the name of the container and an integer. Here, the container name is set to PostgreSQL
It then exposes the Postgres communication port to 5432. This is the standard port for Postgres.
The restart option is set to always to ensure the image is started again if the host is rebooted. There are other options available, these options can be found here: Docker-compose:Restart
Then the environment file is set by pointing env_file to .env. This allows the use of predefined variables instead of editing the docker-compose file to set things such as volumes.
The Postgres image utilises a number of environment variables to set user, password and server details. these values are contained within the .env file as POSTGRES_USER, POSTGRES_PASSWORD, POSTGRES_DB. They can be changed within the .env file.
Finally, the volumes are set.
The first one:
"$ROOT/postgresql:/var/lib/postgresql/data"
This makes the Postgres image persist data in a local folder ./postgressql. Doing this prevents data from being lost if the image is stopped. However, if docker-compose down -v is run then the persistant data will be removed.
The $ROOT value is stored in the environment file, and can be configured there.
The second volume:
./setup/postgres/init.sql:/docker-entrypoint-initdb.d/init.sql
This is used to recreate the Postgres database from scratch in the case of starting everything with ./docker-compose up.
The official Postgres docker image will run .sql scripts found in the /docker-entrypoint-initdb.d/ folder. So that is used by pointing /docker-entrypoint-initdb.d/init.sql to a local file.
The Postgres image can be stopped and restarted again individually. Since the container name was set in the configuration, the following can be applied:
docker stop PostgreSQL
docker restart PostgreSQL
Adminer
Adminer is a database management console.
adminer:
image: adminer
container_name: adminer
restart: always
depends_on:
- PostgreSQL
ports:
- 8080:8080
The image is set to use the adminer image, and the container name is set to be adminer instead of the automatically generated container name.
Again, the restart option is set to always so that adminer will restart on power loss.
Depends_on is set to PostgreSQL since this is the management console for it.
The port 8080 is then exposed allowing users to access it. It is typically accessed via http://localhost:8080
Since everything is being launched by docker-compose, there is a background network created that allows the services to communicated with each other. Each service takes the interface name from the configuration file. So the Postgres server will be called PostgreSQL.
When logging in via the Adminer console, the System should be set to Postgres and the Server should be set to PostgresSQL
The username, password and database to connect to can be found within the .env file as POSTGRES_USER, POSTGRES_PASSWORD, POSTGRES_DB.
Redis
Redis is an open source key-value store that functions as a data structure server.
redis:
image: redis:alpine
container_name: redis
restart: always
volumes:
- "$ROOT/redis:/data"
The image is set to use the lightweight redis:alpine image, and the container name is set to be redis instead of the automatically generated container name.
Again, the restart option is set to always so that adminer will restart on power loss.
The persistent data volume is set to be ./redis based by using the ROOT value from the .env file.
A blank configuration file is included in the ./setup/redist folder. If this is required to configure redis, then an additional volume should be added to the image. Such as:
redis:
image: redis:alpine
container_name: redis
restart: always
volumes:
- "$ROOT/redis:/data"
- "./setup/redis/redis.conf:/usr/local/etc/redis/redis.conf"
Web
This is a small NodeJS based server, every 15 seconds it insert data into the database. It also serves a small single page app which retrieves the data from the server and displays a list of entries.
It is an example of how to use Docker Compose to build an app from the source code then serve it.
web:
build: ./setup/web/.
container_name: web
command: npm run start
volumes:
- /usr/app/node_modules
ports:
- 9000:9000
depends_on:
- PostgreSQL
- redis
environment:
- HOST=${HOST}
- DATABASE=${POSTGRES_DB}
- USER=${POSTGRES_USER}
- PASSWORD=${POSTGRES_PASSWORD}
- DATABASE_URL=${DATABASE_URL}
There is no offical image for this, as it builds a new 'image' using the Dockerfile in ./setup/web.
This Dockerfile creates a new Node container, copies all the files in ./setup/web into it then runs npm install. This creates the base image for the container.
The container name is set to be web instead of the automatically generated container name.
The command to run once the image has been built is npm run start. This launches a NPM script inside the package.json file copied to the container.
A persistent volume is created for the node app on /user/app.
Depends_on is set to PostgreSQL and redis as these are required to be installed before this app can be run.
The database connection information is sourced from the .env file and passed to the Node app via environment variables.
When the web app is finally running it can be available from http://localhost:9000