79 lines
2.4 KiB
ReStructuredText
79 lines
2.4 KiB
ReStructuredText
======================================
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Docker base image for Monasca services
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======================================
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This image is used as a starting point for images of all Monasca services.
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Building monasca-base image
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===========================
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You need to have Docker installed (minimum tested version is ``17.09``).
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Then you can build image inside of this folder by running:
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``docker build --no-cache -t monasca-base:1.0.0 .``
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Building child image
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--------------------
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In the ``example`` folder you can find samples of how to start building
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new child image using ``monasca-base``.
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Requirements
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~~~~~~~~~~~~
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Every child image has to provide two files:
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start.sh
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In this starting script provide all steps that lead to the proper service
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start. Including usage of wait scripts and templating of configuration files.
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You also could provide the ability to allow running container after service
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died for easier debugging.
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health_check.py
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This file will be used for checking the status of the application running in
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the container. It should be used to inform Docker that service is operating
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and healthy. It will be useful for container orchestration like Kubernetes
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or Docker Swarm to properly handle services that are still running but
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stopped being responsive. Avoid using `curl` directly and instead, use
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`health_check.py` written with specific service in mind. It will provide more
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flexibility like when creating JSON request body.
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Wait scripts
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------------
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Some Python libraries are already pre-installed: `pykafka` and `PyMySQL`. They
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are used by wait scripts and in the process of creating the child image `pip3`
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will reinstall them to use proper versions confronting the upper constraints
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file.
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These wait scripts will be available in every child image and can be used in
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`start.sh` to avoid unnecessary errors and restarts of containers when they
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are started.
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::
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python3 /kafka_wait_for_topics.py || exit 1
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python3 /mysql_check.py || exit 1
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/wait_for.sh 192.168.10.6:5000 || exit 1
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Please, check the content of each of these files for documentation of what
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environment variables are used and more usage examples.
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Useful commands
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---------------
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List all labels of the image (you need to have ``jq`` installed):
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``docker inspect monasca-api:master | jq .[].Config.Labels``
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Get all steps of the Docker image build process history:
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::
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docker history --no-trunc <IMAGE_ID>
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docker history --no-trunc monasca-base:1.0.0
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