How to link MySQL RDS in docker-compose.yml file? - docker

Question

Instead of below mysql container DB link, I want to link AWS Mysql RDS in docker yml file. Is it possible?
mysql_db:
image: mysql:5.6
container_name: shishir_db
environment:
MYSQL_ROOT_PASSWORD: "xxxxxxxx"
#MYSQL_USER: "shishir"
#MYSQL_DATABASE: "shishir1"
MYSQL_PASSWORD: "xxxxxxxx"
ports:
- "3306:3306"

Answer 1

There are a couple of ways that you can link to a AWS RDS MySQL instance from your docker-compose.yml.
The first, and perhaps simplest way is to set environment variables on the containers that need access to the RDS MySQL instance. So for example, you could update your OperationEngine service definition to look something like:
OperationEngine:
image: shishir/operationengine:${RELEASE_OTA_VERSION}
container_name: operation_engine
ports:
- "8080:8080"
environment:
- DOCKER_HOST_IP: ${DOCKER_HOST_IP}
- JAVA_OPTS: ${JAVA_OPTS}
- MYSQL_HOST: "your-mysql-cname.rds.amazon.com"
- MYSQL_USER: "username"
- MYSQL_PASSWORD: "password"
volumes:
- ${HOME}/operationengine/logs/:/usr/local/tomcat/logs/
You can then update the configuration in that service to read database connection details from the environment e.g ${MYSQL_HOST}.
The obvious downside to this approach is that you have connection details stored as plain text in your docker-compose.yml, which is not great, but may be acceptable depending on your requirements.
The 2nd approach (and the one I tend to favour) is to bind mount the database configuration into the running container.
Most applications support reading database connection details from a properties file. As an example: lets say that on start-up your application read from /config/database.properties and required the following properties to connect to the database:
config.db.host=your-mysql-cname.rds.amazon.com
config.db.user=foo
config.db.password=bar
I would setup my environment so that at runtime, I bind mount a properties file that provides all of the required values to the container:
OperationEngine:
volumes:
- /secure/config/database.properties:/config/database.properties
The /secure/config directory is part of the filesystem on your Docker host. How that directory gets created and populated is up-to-you. Typically I approach this by having my environment setup scripts make the directory and then clone a private Git repository into this directory which contains the correct configuration for that environment. Naturally only those with the required permission levels can view the Git repositories that contain sensitive configuration details i.e. for production system.
Hope that helps.

Answer 2

No, i have not created networking in my yml file. Below is the entirecontent of my yml file, so what changes would be required?
mysql_db:
image: mysql:5.6
container_name: shishir_db
environment:
MYSQL_ROOT_PASSWORD: "xxxxxxxx"
#MYSQL_USER: "shishir"
#MYSQL_DATABASE: "shishir1"
MYSQL_PASSWORD: "xxxxxxxx"
ports:
- "3306:3306"
zookeeper:
image: wurstmeister/zookeeper
container_name: zookeeper
ports:
- "2181:2181"
kafka:
image: shishir/kafkaengine:0.10
container_name: kafka
links:
- zookeeper
ports:
- "9092:9092"
environment:
KAFKA_ADVERTISED_HOST_NAME: ${DOCKER_HOST_IP}
KAFKA_ZOOKEEPER_CONNECT: ${DOCKER_HOST_IP}:2181
KAFKA_ADVERTISED_PORT: 9092
KAFKA_CREATE_TOPICS: ${KAFKA_TOPICS}
KAFKA_ZOOKEEPER_SESSION_TIMEOUT_MS: 12000
KAFKA_ZOOKEEPER_CONNECTION_TIMEOUT_MS: 12000
flywaydb:
image: shishir/flywaydb
container_name: flywaydb
links:
- mysql_db
OperationEngine:
image: shishir/operationengine:${RELEASE_OTA_VERSION}
container_name: operation_engine
links:
- mysql_db
ports:
- "8080:8080"
environment:
DOCKER_HOST_IP: ${DOCKER_HOST_IP}
JAVA_OPTS: ${JAVA_OPTS}
volumes:
- ${HOME}/operationengine/logs/:/usr/local/tomcat/logs/