The following lists the technical requirements to complete this chapter:

• Prerequisite software installed as per instructions in Chapter 1
• GitHub account created as per instructions in Chapter 1

The following GitHub URL contains the code samples used in this chapter: https://github.com/docker-in-aws/docker-in-aws/tree/master/ch2.

Check out the following video to see the Code in Action:
http://bit.ly/2PJG2Zm

In the previous chapter, you gained a good understanding of what the sample application is, and how to test and run the application in your local development environment. You are now ready to start creating a Docker workflow that will test, build, and package your application into a Docker image.

It is important to understand that whenever you are packaging an application into a Docker image, the best-practice approach is to reduce or eliminate all development and test dependencies from your final packaged application. By my own convention, I refer to this packaged application—free of test and development dependencies—as a release image, which supports the paradigm of continuous delivery, where every successful build should be a release candidate that is able to be published to production if required.

To...

In the previous section, you used Docker commands to perform the following tasks:

• Build a test image
• Run tests
• Build a release image
• Run the application

Each time we ran a Docker command, we had to supply quite a bit of configuration, and trying to remember the various commands that you need to run is already starting to become difficult. In addition to this, we also discovered that to start the release image for the application, we need to have an operational external database.  For local testing use cases, running an external database in another container is an excellent approach, but having to orchestrate this by running a series of Docker commands with lots of different input parameters very quickly becomes difficult to manage.

Docker Compose is a tool that allows you to orchestrate multi-container environments...

At this point, you have managed to successfully configure Docker Compose to build, test, and create a working local environment for the sample application, complete with MySQL database integration and acceptance tests.  You can now stand up this environment with a handful of commands, but even though using Docker Compose has significantly simplified the commands you need to run, it is still difficult to remember which commands to use and in which order. Ideally we want a single command to run the complete workflow, and this is where a tool such as GNU Make is very useful.

Make has been around a long time, and is still considered the build tool of choice for many C and C++ applications. Task automation is a key feature of Make, and the ability to define tasks or targets in a simple format that can be invoked with a single command has made...

In this chapter, you implemented a Docker workflow that tests, builds, and packages your application into a Docker image that is ready to publish and deploy to production. You learned how you can build your application in two stages using Docker multi-stage builds—the test stage uses a development environment complete with development libraries and source compilation tools that allows you to build and test your application and its dependencies in precompiled packages, while the release stage takes those built packages and installs them into a production-ready operating environment, free of development libraries and other tools, significantly reducing the attack surface of your application.

You learned how you to use Docker Compose to help simplify the various commands and actions you need to perform during the test and release stages, creating a docker-compose.yml...

1. True/false: You use the FROM and TO directives to define a multi-stage Dockerfile.
2. True/false: The docker command --rm flag automatically deletes a container after it has exited.

3. True/false: When you run your workflow, you should only build application artifacts once.
4. True/false: When running the docker-compose run command with no additional flags, if the targeted services started fails with an error, docker-compose will exit with a non-zero code.
5. True/false: When running the docker-compose up command with no additional flags, if one of the services started fails with an error, docker-compose will exit with a non-zero code.
6. True/false: You should configure a Docker Compose version of 3.x if you want to use Docker Swarm.
7. You configure the service_healthy condition on a dependency of a service in your Docker file.  Then you run the service using...

You can check the following links for more information about the topics covered in this chapter:

• Docker Command-Line Reference: https://docs.docker.com/engine/reference/commandline/cli/
• Docker multi-stage builds: https://docs.docker.com/develop/develop-images/multistage-build/
• Docker Compose Version 2 Specification: https://docs.docker.com/compose/compose-file/compose-file-v2/
• Docker Compose Command-Line Reference: https://docs.docker.com/compose/reference/
• Docker Compose start order: https://docs.docker.com/compose/startup-order/
• uWSGI Quickstart for Python Applications: http://uwsgi-docs.readthedocs.io/en/latest/WSGIquickstart.html
• Bash-Automated Test System: https://github.com/sstephenson/bats
• GNU Make Phony Targets: https://www.gnu.org/software/make/manual/html_node/Phony-Targets.html
• GNU Make Functions: https:...