runner: some aws instances don't shut down and keep running forever

[courentin]

When running cml runner, I've noticed a couple of times that some aws instances were not properly terminated when jobs were finished. However, the gihub runner was marked as offline.

I can't reproduce it easily, it seems to happen in a particular scenario that I can't isolate for now. Also I don't have the bandwidth to investigate more for now.

However, as a broader issue here, I'm wondering if the instance termination is resilient enough to diverse failures.
Given that cml is made for ML workflows, we expect users to run big/expensive instances. Thus, cml should ensure that no matter what happen (github action's down, cml bug, particular edge case with canceling workflows, etc.) instances must be shut down at some point.

When cml didn't existed, we used to start instances manually and figured out it was easy to forget about them. To fix that, we developed an EC2 instance garbage collector that terminated instances with low CPU usage for a certain amount of time.
If that kind of stuff can be integrated to cml, that would be awesome.

[dacbd]

Thanks, @courentin I have had 2 recent occurrences of cml not terminating properly internally as well and I believe there may be an issue with how we are determining idleness. Additionally (depending on use), there may be instances with expired credentials, thus unable to delete themselves (ex. using OIDC).

• Can you share the gist of the flags you are using with cml runner where the instances aren't terminating?
• I have an internal action that checks AWS for still present cml instances; with a bit of clean-up, we could probably share this as a composite action. Would something like this be helpful as simple additional tool/action?

I often add this example line to help link instances back to there ci runs: --cloud-metadata="actions_link=https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}"

[courentin]

Here is the exact cml runner options that we use:

cml runner
--name=${{ steps.cml_name.outputs.id }}
--cloud=aws
--cloud-region=${{ matrix.aws_region }}b
--cloud-type=g4dn.xlarge
--labels=cml,${{ matrix.aws_region }},${{ steps.cml_name.outputs.id }}
--cloud-metadata="Project=speech-models"
--cloud-metadata="Service=ml-infra"
--cloud-metadata="CreatedBy=cml"
--reuse-idle
--idle-timeout=600

I have an internal action that checks AWS for still present cml instances; with a bit of clean-up, we could probably share this as a composite action. Would something like this be helpful as simple additional tool/action?

That would be awesome!

I often add this example line to help link instances back to there ci runs: --cloud-metadata="actions_link=https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}"

Nice, will do the same!

[dacbd]

@courentin do you by chance have multiple runners created in parallel with the snippet you shared?

• How many instances/runners are created?
• What is the general format of ${{ steps.cml_name.outputs.id }} ?
• Do you only have one stale instance from this type of invocation or multiple?

[courentin]

@courentin do you by chance have multiple runners created in parallel with the snippet you shared?

Yes we can if two PR are open at the same time. But one PR should create one runner.

How many instances/runners are created?

1 per PR

What is the general format of ${{ steps.cml_name.outputs.id }} ?

The same as the default one, we use it to be able to use it in some steps after

Do you only have one stale instance from this type of invocation or multiple?

Good question, as I'm not able to reproduce it now I can't be 100% sure, but I'd say 1

[courentin]

Just figured out I have 8 instances running and github tells me they are offline.
They all reached their storage limit and jobs failed with the following error, thus I suspect this is why they become unavailable to the github runner:

System.IO.IOException: No space left on device : '/tmp/tmp.LR2kETHcwX/.cml/cml-by6mft0ge1/_diag/Worker_20220919-124453-utc.log'
   at System.IO.RandomAccess.WriteAtOffset(SafeFileHandle handle, ReadOnlySpan`1 buffer, Int64 fileOffset)
   at System.IO.Strategies.BufferedFileStreamStrategy.FlushWrite()
   at System.IO.StreamWriter.Flush(Boolean flushStream, Boolean flushEncoder)
   at System.Diagnostics.TextWriterTraceListener.Flush()
   at GitHub.Runner.Common.HostTraceListener.WriteHeader(String source, TraceEventType eventType, Int32 id)
   at GitHub.Runner.Common.HostTraceListener.TraceEvent(TraceEventCache eventCache, String source, TraceEventType eventType, Int32 id, String message)
   at System.Diagnostics.TraceSource.TraceEvent(TraceEventType eventType, Int32 id, String message)
   at GitHub.Runner.Worker.Worker.RunAsync(String pipeIn, String pipeOut)
   at GitHub.Runner.Worker.Program.MainAsync(IHostContext context, String[] args)
System.IO.IOException: No space left on device : '/tmp/tmp.LR2kETHcwX/.cml/cml-by6mft0ge1/_diag/Worker_20220919-124453-utc.log'
   at System.IO.RandomAccess.WriteAtOffset(SafeFileHandle handle, ReadOnlySpan`1 buffer, Int64 fileOffset)
   at System.IO.Strategies.BufferedFileStreamStrategy.FlushWrite()
   at System.IO.StreamWriter.Flush(Boolean flushStream, Boolean flushEncoder)
   at System.Diagnostics.TextWriterTraceListener.Flush()
   at GitHub.Runner.Common.HostTraceListener.WriteHeader(String source, TraceEventType eventType, Int32 id)
   at GitHub.Runner.Common.HostTraceListener.TraceEvent(TraceEventCache eventCache, String source, TraceEventType eventType, Int32 id, String message)
   at System.Diagnostics.TraceSource.TraceEvent(TraceEventType eventType, Int32 id, String message)
   at GitHub.Runner.Common.Tracing.Error(Exception exception)
   at GitHub.Runner.Worker.Program.MainAsync(IHostContext context, String[] args)
Unhandled exception. System.IO.IOException: No space left on device : '/tmp/tmp.LR2kETHcwX/.cml/cml-by6mft0ge1/_diag/Worker_20220919-124453-utc.log'
   at System.IO.RandomAccess.WriteAtOffset(SafeFileHandle handle, ReadOnlySpan`1 buffer, Int64 fileOffset)
   at System.IO.Strategies.BufferedFileStreamStrategy.FlushWrite()
   at System.IO.StreamWriter.Flush(Boolean flushStream, Boolean flushEncoder)
   at System.Diagnostics.TextWriterTraceListener.Flush()
   at System.Diagnostics.TraceSource.Flush()
   at GitHub.Runner.Common.TraceManager.Dispose(Boolean disposing)
   at GitHub.Runner.Common.TraceManager.Dispose()
   at GitHub.Runner.Common.HostContext.Dispose(Boolean disposing)
   at GitHub.Runner.Common.HostContext.Dispose()
   at GitHub.Runner.Worker.Program.Main(String[] args)

[0x2b3bfa0]

I wonder if using systemd slices to prevent resource exhaustion as @dacbd suggested could help fix this issue. 🤔

[dacbd]

Indeed, for my bits of experimenting, I think that the easiest way to handle this on our end, would be by creating a 500 MB file during provisioning that we mount as a disk to the terraform dir. The terraform destroy fails because it can't create a new file. Having a premade file mounted as a block device for that dir should allow the destroy to go through regardless of the user filling the disk.

@courentin your input here would be helpful to increase some visibility (trying to GitHub to improve some messaging) https://github.com/orgs/community/discussions/30440

[courentin]

@dacbd Unfortunately I never encountered the message "The self-hosted runner"

[0x2b3bfa0]

Sorry for the belated reply, @courentin.

Although there isn't an easy way of making sure that no instance is left running after a crash, we'll try to fix this particular edge case, where instances run out of disk space.

In the meantime, and once you've identified your storage requirements, it might be a good idea to explicitly set cml runner --cloud-hdd-size to a more generous value.