Skip to content

Latest commit

 

History

History
56 lines (35 loc) · 2.63 KB

0148-taskcluster-worker-location.md

File metadata and controls

56 lines (35 loc) · 2.63 KB
Raw

RFC 148 - TASKCLUSTER_WORKER_LOCATION

  • Comments: #148
  • Proposed by: @djmitche

Summary

This proposal defines an environment variable, TASKCLUSTER_WORKER_LOCATION, containing this information in an easily-digested format.

Motivation

Workers often need information about where they are running, for example to select nearby mirrors or other resources.

Taskcluster does not currently provide this in a documented, supported fashion.

Details

This proposes to introduce $TASKCLUSTER_WORKER_LOCATION as an environment variable available within tasks run by docker-worker and generic-worker. The variable's value is a short chunk of JSON, with a top-level object. If no location is available, workers will not set this variable.

That object must always have property cloud. The remaining properties depend on the value of that property, but are fixed for each such value. For example, if cloud is amazon, then a well-defined set of additional properties will always exist. The term "cloud" is used loosely as a category of location, and need not correspond to a commercial cloud provider. For example, users deploying Taskcluster might define "clouds" such as onprem or macstadium.

The precise structure for each cloud will be defined by the configuration for the workers. In cases where worker startup is handled by providers in taskcluster-worker-runner, it will be defined in that tool's documentation.

Implementation

Determining Location

Taskcluster-worker-runner already posesses special-case code for each cloud, and makes queries to those clouds' metadata services. As such, it is well-suited to determine the location in each cloud.

It will pass this information on to workers as a configuration option, and the workers will include it in the task environment.

Parsing

Since the value is in a JSON format, it is not easily used in a shell script. Use of grep to parse the value is strongly discouraged. The jq utility can be useful, e.g., echo $TASKCLUSTER_WORKER_LOCATION | jq -r .cloud;

Documentation

The taskcluster service docs on environment variables already specify several variables that are available to tasks. TASKCLUSTER_WORKER_LOCATION will be added to the list, with reference to tc-worker-runner's documentation for per-cloud definition of <details>.

Credits

Thanks to @imbstack, @owlishDeveloper, and @walac for early discussion of this issue.

Implementation Links