Rebuild FIDO2 dependencies on failure

[codingllama]

Attempt to detect builder environment inconsistencies by compiling a toy FIDO2 program - if this fails, then clear the cache and try again.

Builders are sometimes getting into inconsistent states, this should help avoiding manual intervention in order to fix them.

[codingllama]

Two Mondays in a row now I've had headers missing from include/ inside cached libraries. It's not clear how the builders are getting into that state - the script itself is not destructive and my expectation would be for /tmp to cleared entirely.

This is a an attempt to avoid rebuilding everything on every job, which saves time and energy (plus rebuilding brings its own complications). If this keeps causing us woes, then I would reconsider.

[espadolini]

@codingllama according to https://superuser.com/a/187105, files in /tmp are cleared out after 3 days of not being accessed - which aligns suspiciously with the amount of time that passes between EoB on friday and SoB on monday 👀

Perhaps we just need to move the build cache away from /tmp and into ~/.teleport-fido2-cache?

[codingllama]

@espadolini yep, it does look like a period cleanup. The interesting part is that it deletes a bunch of headers but has tendency to keep libs around (even dylibs that we don't use), whereas I was (innocently) expecting a folder-wipe kind of deal.

Drone changes $HOME to a per-build temporary directory, that's why many of our "script caches" use /tmp instead.

[codingllama]

Friendly ping @EdwardDowling @smallinsky ?

[smallinsky]

LGTM.

The other approach is to calculated and store in a file the directory checksum for each lib dir content like: find $CBOR_PATH -type f -exec shasum {} \; | sort -k 2 | shasum and compare the saved value with value calculated based on current build state.

[espadolini]

Still, isn't there some other persistent absolute path we could use?

[codingllama]

@espadolini and I discussed a few options, the only persistent path that builders can write to is $HOME (or /Users/$(whoami)). The latter is easy enough to do, just a bit outside of what a Drone script should do (although one could argue this ship kind of sailed already).

What do you say we give this a try? If it bites us again then I'll backpedal into separate library builds for every pipeline, which is of course slower but nicely isolated.

[codingllama]

Friendly ping @EdwardDowling @espadolini ? Could we get this one in?

[espadolini]

+1 for just using /Users/$(whoami)/.teleport-fido2-cache too

[codingllama]

Thanks for the quick reply.

I'm hoping this script will go away in favor of a better solution in the near future, so I'll push as-is. I may revisit with the shasum//Users/$(whoami) ideas if I get some spare time soon.

[codingllama]

/gcbrun