Looking at the new timeline view made me consider how we could instrument our slower build steps. It would be great to provide an api where we would send events from within the build steps.
In our case that is ansible but I think if you provided a way to send a GET request with the build slug it would help expose custom start/stop events.
Hi @angusscown!
Good eye, we’ve been having similar thoughts. We’re very keen to start exploring observability throughout builds. 
There’s some pretty exciting work to add tracing to the Buildkite Agent over here:
and experiments with tools like Jaegar, too:
We’d love to hear about what you’d like to see in this timeline, and how you think it would help. 
Cheers,
Sam
I too would like to be able to add additional custom items to a timeline.
Hey @simonbyrne
Thanks for the message.
Just to clarify you are talking about the timeline tab in the UI?
Could you please specify what custom items you are looking to add, and how they would be beneficial to your use case?
Cheers!
In our particular case, we run our buildkite jobs inside a separate job scheduler (Slurm). For debugging purposes, it would be useful to be able to attach various metadata to a job (such as the Slurm job id) before the agent for the job has actually started.
Hey @simonbyrne
The purpose of the timeline tab is to provide live updates on agent and dispatcher events as well as information of the job running on the agent.
The agent and the job will need to be started to add a meta-data. Currently we do not support customizing this feature
Cheers!