Add a device to mount the host /dev/shm inside the container.

[jschwartzentruber]

We do this when fuzzing, since Firefox needs a lot of space in /dev/shm and sizing it properly is not straightforward.

[community-tc-integration]

No Taskcluster jobs started for this pull request

The `allowPullRequests` configuration for this repository (in `.taskcluster.yml` on the
default branch) does not allow starting tasks for this pull request.

[walac]

The way it is currently implemented, the worker will lose its feature of running parallel tasks, as the device capacity will never be greater than 1

[walac]

In general, it LGTM. I would only ask you to fix the linter complaints and add a test case. Thanks.

[walac]

I created a PR in the community repo to add the shared memory capability scope.

[walac]

There is something wrong with the linter task, but I am quite sure it is unrelated to your patch. I am going to investigate it.

[walac]

Ok, I found out what's wrong. As you added the hostSharedMemory to .taskcluster.yml this created a chicken-egg problem, since the currently deployed docker-worker obvisiously doesn't support this device. I wonder how tests were passing before.

[jschwartzentruber]

How do we get around this chicken-egg problem? Is there anything for me to do?

[walac]

There is a problem while runnings tests for shm. I believe it is related to docker-in-docker. I disabled the integration test and marked the shm device support is experimental. Merging now.