donhenton/udemy-docker

docker excercises for udemy class

Docker Demonstration of two Docker containers communicating

Course

https://www.udemy.com/docker-tutorial-for-devops-run-docker-containers

Instructions

The instructions below refer to files in the spring-boot-redis folder

Container 1

• Redis
• docker pull redis:3.2.0 (runs redis on port 6379)

Container 2

• Spring Boot Web App see build.sh

Running the two containers

• see rr.sh
• the boot webapp will run via Netbeans boot as well, but will look for the dockerlocal to find the redis server
• this is overrun by the environment variable to point to the link name

Communication between the containers

• --link points to the name of the redis-container
• this turns the name into the host_name for the redis server
• the spring boot env variable sets boot to override the redis_host variable in app props

Link command places host entries

• the link command places a host entry into the etc/hosts file of the source container. You can view assigned internal ips using

docker inspect | grep IP

Docker Compose

• dup.sh illustrates docker compose for the redis server and the boot client startup
• build is done prior to docker compose command (mvn and docker-compose)
• the env variable issue is set in the docker-compose.yml file
• the volumes command in the docker-compose file maps the docs folder to app folder inside the container
• ddown.sh will bring the containers down and delete them, also removes any volume mappings
• a .env file (at the same location as the yml file) can be used for global env variables that can be substituted in the yml file via ${VAR_NAME}
• a separate file can be specified with variables only available to the container (env_file: .env_fred) these will be specific to the container

Docker Compose Commands

• docker-compose ps (see all services under the current docker-compose)
• docker-compose logs (-f) to follow
• docker-compose logs -f
• docker-compose stop (to stop with out delete)
• docker-compose start (to restart)
• docker-compose rm to remove the containers

Docker Registry Folder

Docker compose file for docker registry

Jenkins Server Folder

Docker compose file for Jenkins server, Jenkins slave and Docker Registry