Using Containers for Continuous Deployment


Test Automation
The more efficient usage of resources and almost instant startup times provided by containers is hugely important for super-fast continuous integration builds, but there are even bigger benefits for large test execution scenarios.

Today, the redeployment of a full operating system for the each test automation suite is out of the question, therefore the same system is used to execute hundreds or even thousands of test cases in a quick succession. This requires very sophisticated teardown procedures between the execution of the test suites, which is often a source of errors. Such errors may cause a butterfly effect, leading to an unexpected failure in an unrelated part of the test execution. In addition, teardown procedures are expensive to write and maintain and may take significant time to execute.

With containers, we can eliminate teardown procedures entirely. Every single test automation suite can run in a separate disposable container, which can simply be thrown away after execution. A notable side effect of this is that we can now run all the tests in fully isolated containers in parallel and on any hosting environment that supports containers. This can potentially reduce test automation time from hours to minutes or even seconds depending on the resources at your disposal.

DevOps and Continuous Delivery
The DevOps movement is increasingly popular and aims to bridge the communication gap between development and operations. I see the creation of a common technical language as one of the biggest challenges for DevOps, since these two departments have typically been trying to solve different problems. Although containers will not fix or resolve this challenge, they may significantly simplify the situation for both parties and create an environment, which is easily accessible for both programmers and IT operators.

The standardization of tooling in both departments will allow software to move faster through the pipeline and reduce the complexity required at each stage. By doing that we can take another step towards faster feedback loops with continuous delivery.

In Conclusion
Modern software development relies on the extensive reuse and integration of existing software components. This makes setting up development and production environments especially challenging.

Containers have been here for a while, but only recently have they become reliable and usable enough for daily operations. They will very soon allow us to remove the burden of running thousands of unneeded operating system instances and focus on the real services we provide to our customers.

Containers are making continuous deployment look like an achievable goal.

User Comments

Clifford Berg's picture

The author makes a great point that is often overlooked - the fact that containers are so disposable - one need to do test teardown because one does not need to reuse a container. In devops processes people often rebuild their environments only daily - or less frequently - because of the time it takes. But if one creates a container image from a good baseline, one can reload that image almost instantly, use it for testing, and then throw it away - one can then always use clean test environments.

November 2, 2015 - 4:26pm

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