monasca-common/docker/README.rst

Docker base image for Monasca services

This image is used as a starting point for images of all Monasca services.

Building monasca-base

You need to have Docker installed (minimum supported version is 17.09). Then you could build image inside of this folder:

docker build --no-cache -t monasca-base:1.0.0 .

Building child image

In the example folder you could file sample of how to start building new child image using monasca-base as start.

Requirements

Every child image need to provide two files:

start.sh

In this starting script provide all steps that direct to proper service start. Including usage of wait scripts and templating of configuration files. You also could provide ability to allow running container after service died for easier debugging.

health_check.py

This file will be used for checking status of application running in the container. It will be useful for programs like Kubernetes or Docker Swarm to properly handle services that are still running but stopped being responsive. Avoid using curl directly and instead use health_check.py written with specific service in mind. It will provide more flexibility like when creating JSON request body.

Wait scripts

Some Python libraries are already preinstalled: pykafka and PyMySQL. They are used by wait scripts and in the process of creating child image pip3 will reinstall them to proper versions confronting to upper constraints file.

This wait scripts will be available in every child image and could be used in start.sh to avoid unnecessary errors and restarts of containers when they are started.

python3 /kafka_wait_for_topics.py || exit 1
python3 /mysql_check.py || exit 1
/wait_for.sh 192.168.10.6:5000 || exit 1

Please, check content of every of this files for documentation of what environment variables are used and more usage examples.

Useful commands

List all labels on image (you need to have jq installed):

docker inspect monasca-api:master | jq .[].Config.Labels

Get all steps from what Docker image was build:

docker history --no-trunc <IMAGE_ID>
docker history --no-trunc monasca-base:1.0.0