How do I change the GHCup metadata cache timeout and/or make the updates quieter?
I have seen this quite a few times today:
tc$ ghcup list -t cabal
[ Info ] downloading: https://raw.githubusercontent.com/haskell/ghcup-metadata/master/ghcup-0.0.9.yaml as file /home/cjs/.ghcup/c
ache/ghcup-0.0.9.yaml % Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0
Tool Version Tags Notes
✗ cabal 2.4.1.0
✗ cabal 3.0.0.0
...
In fact, since I'm using ghcup a fair amount while testing some things, I am seeing it every five minutes or so.
The entirety of the documentation on this seems to be:
Metadata cache
The metadata files (also see github.com/haskell/ghcup-metadata) have a 5 minutes cache per default depending on the last access time of the file. That means if you run ghcup list 10 times in a row, only the first time will trigger a download attempt.
Is there any way to change this cache timeout to something much longer? To me it seems reasonable just to check once a day, or once every few hours at most. After all, how often are new versions of GHC/Cabal/HLS/Stack released? (Or is there something I'm missing here that wants faster updates? The ghcup-metadata repo can easily go a couple of weeks without an update.
Answer
The Configuration section of the documentation explains that there is a configuration file. The file syntax is not documented on the site itself (which is why searching the site pages won't find the meta-cache config option), but it directs you to a commented sample file in the source code. Here is the relevant extract:
# The caching for the metadata files containing download info, depending on last access time
# of the file. These usually are in '~/.ghcup/cache/ghcup-<ver>.yaml'.
meta-cache: 300 # in seconds
Thus, adding meta-cache: 86400 to your ~/.ghcup/config.yaml will change the timeout to one day.
Note that later entries override earlier entries (this is not documented), so if you leave the default meta-cache: null that was placed in that file when it was installed, your meta-cache: entry must be in the file after that line in order to override it.