FWIW, it looks like the recent "successful" builds are just no-ops because it's a cron builder, so it runs whether or not a new tarball is needed, and for the last few days, it seems to think there isn't one needed.

The last run that actually did something was:
https://ci.chromium.org/buildbot/chromium.infra.cron/publish_tarball/9422

I think it's because 'version' is not in the build properties:
https://cs.chromium.org/chromium/infra/recipes/recipes/publish_tarball.py?rcl=38fae909e791bef4fb775a1901421b64972f1ee2&l=161

eg. This build which had 'version' built and published the tarballs:
https://ci.chromium.org/buildbot/chromium.infra.cron/publish_tarball/9455
But this one without 'version' didn't:
https://ci.chromium.org/buildbot/chromium.infra.cron/publish_tarball/9454

If I understand the flow correctly, the builder actually triggers itself when there's a new version ready, so the "version" property comes from a previous run (see the "trigger" step in https://ci.chromium.org/buildbot/chromium.infra.cron/publish_tarball/9421)

I think I know what's happening.  The script only includes versions that are tagged with stable, beta, or dev, but dev releases don't occur nightly.

Linux doesn't have a canary channel, but perhaps we could include that anyway?

Include what anyway? tarballs for nightly canaries?

Yes.  Ideally I want to get a faster turnaround when making fixes for the tarballs.  eg. I'm currently waiting for a new tarball to verify a fix for  bug 799620 .

Also, I'm planning on adding a bot that does builds from the tarballs, and it would be nice to have it run nightly.

I don't know what the original rationale was for not including canary (I assume it's just too much unnecessary stuff), so I'd be hesitant to add it. However, you could theoretically use buildbucket to trigger one-off builds, by mimicking what the script does to trigger itself. Would that suffice for the current bug?

That works for the current bug.  But like I said, I'm adding a bot that does tarball builds.  The hope is that we'll be able to catch regressions sooner with the nightly builds so that folks who pull the dev (or other) tarballs are less likely to run into some kind of build failure.

The following revision refers to this bug:
  https://chromium.googlesource.com/infra/infra/+/5d34556594153bba1060ff68b79a3a7d9db5b6bb

commit 5d34556594153bba1060ff68b79a3a7d9db5b6bb
Author: Tom Anderson <thomasanderson@chromium.org>
Date: Wed Jan 10 19:22:31 2018

Start publishing nightly Linux tarballs

BUG= 800409 
R=mmoss

Change-Id: Id3c5af16a0f06524b11e6929a40cb07cecf5b11f
Reviewed-on: https://chromium-review.googlesource.com/857958
Reviewed-by: Michael Moss <mmoss@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>

[modify] https://crrev.com/5d34556594153bba1060ff68b79a3a7d9db5b6bb/recipes/recipe_modules/omahaproxy/api.py
[modify] https://crrev.com/5d34556594153bba1060ff68b79a3a7d9db5b6bb/recipes/recipes/publish_tarball.expected/trigger.json
[modify] https://crrev.com/5d34556594153bba1060ff68b79a3a7d9db5b6bb/recipes/recipes/publish_tarball.py