Typically, an integration test creates one or more containers. This can mean a lot of containers running by the time everything is done. We need to have a way to clean up after ourselves to keep our machines running smoothly.
Containers can be unused because:
- Test is over and the container is not needed anymore.
- Test failed, we do not need that container anymore because next build will create new containers.
As we saw previously there are at least two ways to remove unused containers.
The primary method is to use the
Terminate(context.Context) function that is
available when a container is created. Use
defer to ensure that it is called
on test completion.
defer as soon as possible so you won't forget. The best time
is as soon as you call
testcontainers.GenericContainer but remember to
check for the
Ryuk (also referred to as
Reaper in this package) removes containers/networks/volumes created by
Testcontainers for Go after a specified delay. It is a project developed by the
Testcontainers organization and is used across the board for many of the
different language implementations.
When you run one test, you will see an additional container called
alongside all of the containers that were specified in your test. It relies on
container labels to determine which resources were created by the package
to determine the entities that are safe to remove. If a container is running
for more than 10 seconds, it will be killed.
This feature can be disabled when creating a container or a network, but it can cause unexpected behavior in your environment.
We recommend using it only for Continuous Integration services that have their own mechanism to clean up resources.
Even if you do not call Terminate, Ryuk ensures that the environment will be kept clean and even cleans itself when there is nothing left to do.