We would need to update the app itself, event_mon protos and scripts using event_mon data.

Edward: what shall we do to move forward here? I had a look and the regular bots in chromium.perf already use swarming, so is this a problem specific for us? If so, how do they solve it?

Are they already using LUCI?
This is not related to swarming perf tests.

Ah. I guess not. I was only thinking that the were using swarming, so they should have a similar problem missing the build number, but maybe that's only the case if they're using Luci.

Also: trybots aren't uploading any perf numbers, so I assume you mean to generalize all bots, not just trybots?

I think they plan to have something like build numbers for the regular bots.
I'll check and update the bug.

Since I've moved to V8 team, un-CC-ing myself. Please re-add me if you need my input.

This is now the only blocker left for bug 749696, it seems.
I'll look into how other bots reporting to test-results are doing this.

'linux_chromium_rel_ng', e.g. https://ci.chromium.org/swarming/task/391f1546332a1b10?server=chromium-swarm.appspot.com is successfully uploading to test-results and it passes a --build-number 8905 flag, where this is a build property it gets from 'setup_build'.
I don't see where it comes from though.

buildnumbers can be enabled by setting build_numbers to true https://chromium.googlesource.com/infra/infra/+/d8d84ac/appengine/cr-buildbucket/proto/project_config.proto#210

Example failing WebRTC LUCI tryjob that due to the missing 'buildnumber' property: https://ci.chromium.org/swarming/task/39200b4e43913710?server=chromium-swarm.appspot.com

Re #10 that's great. I'll make a CL for our cr-buildbucket.cfg tomorrow, enabling that then. Thanks!

After submitting https://webrtc-review.googlesource.com/c/src/+/8300
I tried https://ci.chromium.org/swarming/task/39226a79099efd10?server=chromium-swarm.appspot.com but it still fails with the same error (no buildnumber property). Hmmm.

please allow 15min for config propagation

Ah, I tried again now and got a successful build: https://ci.chromium.org/swarming/task/392310826f62cd10?server=chromium-swarm.appspot.com

nodir@ also told me there is (or will soon be) an API to set the value of the counter the build-number is incrementing, so we can align with current buildbot builds (if needed, I'm not sure we care).

> #15
the API was deployed:
https://apis-explorer.appspot.com/apis-explorer/?base=https://cr-buildbucket.appspot.com/_ah/api#p/swarmbucket/v1/swarmbucket.set_next_build_number