[FEAT] Troubleshooting docs for Java runtime memory errors

[mfisher87]

Is this a new feature request?

• I have searched the existing issues

Wanted change

When upgrading from docker-unifi-controller v7 to docker-unifi-network-application, a new dependency on the docker runtime is introduced. With Docker Engine 19.x (yeah, I know), I get in this loop trying to start the container:

There is insufficient memory for the Java Runtime Environment to continue.

Upgrading Docker resolves it.

Reason for change

The error message is a red herring that may distract users from the actual cause. Having some docs in the "Migrating from unifi-controller" section would help users avoid that confusion.

Proposed code change

In the documentation, add:

Older versions of unifi-controller (<=7) support older versions of Docker Engine. Because this image is built on newer versions of the Java base Docker images, it requires a newer version of Docker Engine. If you receive errors like There is insufficient memory for the Java Runtime Environment to continue which can't be explained by actual lack of memory, upgrade Docker Engine to the latest version to resolve.

I'm sure there is a specific version that's required, but I don't know it.

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[aptalca]

I don't think it's worth it to add a message about updating docker to fix a very specific issue. Users should keep their docker installs up-to-date regardless.

[mfisher87]

Thanks for your response!

I don't think it's worth it to add a message about updating docker to fix a very specific issue

I think the cost is really low, and the benefit is also really low, but likely the benefit will be some multiple of the cost. Yes, it's a very specific issue, but it is a breaking change in the dependencies between docker-unifi-controller and docker-unifi-network-application, so I feel the migration guide is an appropriate place to note this.

I'd be happy to open a PR if that would help reduce the cost!

[thespad]

The core issue is covered under https://docs.linuxserver.io/FAQ/#jammy

There's no note in this readme in part because we had taken the view that as 20.10.10 was released 2021-10-25 (i.e. already 2 years old when this repo was created) that anyone capable of upgrading their Docker install would have already done so.

We only tend to call these things out when we consider them a current issue, and even then we tend to use our information channels (info.linuxserver.io / Discord / social media) to broadcast the details because it's a lot of work to update dozens of readmes every time an issue crops up.