With "nix build", just the build of xmonad-contrib itself takes 3
minutes (it builds twice, the second build with profiling enabled), so
it ends up being almost 6 minutes in total, making this workflow the
slowest one.
Building xmonad-contrib benefits greatly from compiling modules in
parallel. Vanessa McHale suggested setting ghc-options in
xmonad-contrib.cabal in #431, but that's bad practice—these options
should be set by the user/environment where it's being built, not
selfishly hardcoded for specific package. In stack.yaml and
cabal.haskell-ci, we know for sure that xmonad-contrib is the terminal
(leaf) library, so we can set it there and speed up builds in our CI and
also for anyone who uses our stack.yaml (not that anyone should).
Closes: https://github.com/xmonad/xmonad-contrib/pull/431
Turns out `commit: master` doesn't really mean latest master, because
it's cached. It sometimes works, because when the GHA cache comes from
a job that depended on xmonad-0.15, then the master archive isn't cached
and is fetched. When the cache comes from a job that previously fetched
master, it's not fetched again.
The least ugly way to fix it I found is to use the `[<refname>]@{<date>}`
git revision format, and substitute current date/time before invoking
stack. To make stack-master.yaml valid without the substitution, we use
`master@{today}` which is a valid git revision that GitHub understands.
GitHub Actions writes caches on the first miss and then never updates
them again. If the CI is used frequently, the caches never expire and
as they get old, become less useful.
To avoid this, force refreshing the caches once a month.
When building with an LTS version that has exactly the dependencies we
need (xmonad-0.15), stack doesn't need to download the Hackage index. If
GitHub Actions cache locking chooses this job as the one that writes the
cache, then the "stack-pantry-Linux" cache entry stays empty, possibly
forever.
Force Hackage index update to prevent this from happening.
This further reduces our usage of cache storage by caching the metadata
only once per repo. Now the metadata cache is ~250MB and the individual
caches with built dependencies are ~10M each.
Related: cfe99998fc
Related: https://github.com/xmonad/X11/pull/75
Stack installation of GHC takes more than a gigabyte, so caching it
wastes space (GitHub docs say it will be aggressively evicted after
reaching the 5G limit) and also time (compression, decompression).
Related: 9fce3805fc
Related: a5cee9bac2
Related: https://github.com/xmonad/X11/pull/75
Drop nightly and lts-15: they don't add GHC versions to the matrix and
new deps are better tested in the haskell-ci (cabal) workflow.
There's also little point in testing against both xmonad 0.15 and xmonad
master with all LTS versions. Drop most of those, reduces GitHub cache
and CPU time usage.
Related: fd243ca1c1
Related: https://github.com/xmonad/X11/pull/75
Last released xmonad doesn't build with GHC 9.0 and haskell-ci doesn't
let us tweak the test matrix easily. Let's hope the stack.yml workflow
is sufficient to test backward compat.
Related: 2a1a18023a
* split into buildenv deps and stack build
* make the deps list more git-friendly
* use stack from github environment (I've seen the curl fail intermittently)
* indent consistency
