We recently deployed an HTTP caching1 layer for pages2, lead by Mac Chaffee3.
All pages sites are now blazing fast -- sorry, I had to say it.
With HTTP caching we need a way to automatically and manually clear the cache. Whenever a user updates their site we will wipe the cache for it. Further, we also provide a remote CLI to let users clear their cache manually:
1ssh pgs.sh cache {project} --write
We are still working through the feature-set for HTTP caching but we think we landed on something that should cover our use cases for awhile.
If anyone notices their site not updating when it should, please let us know so we can investigate.
impl #
Finding an off-the-shelf http caching service was not exactly straight-forward. We spent a considerable amount of time experimenting with various techniques. First we tried caching within our pages service, then decided that it might be better to put it inside our reverse proxy (caddy), and then ultimately decided to put it back inside of our pages service.
There are only a handful of Go http caching libraries and most of them have been archived. It seems, that fully implementing RFC72344 is non-trivial and hard for open-source contributors to maintain.
Thankfully we found souin5 which we can plainly see has had a ton of work put into it. Kudos, darkweak, your hard work on this library was much appreciated -- I really didn't want to implement RFC72344 myself.
Like everything else at pico, we are always looking for ways to dogfood our
services. The cache clearing mechanism mentioned at the beginning of the post
was enabled by pipe[^6], which is our authenticated, networked *nix pipes
service.
We created a pipe topic cache-drain where we send all requests to clear
caches. Then we have a function that subscribes to the cache-drain and clears
our HTTP cache.
What's really nice is our observability over the cache drain. We now have a
single channel where we can view all requests being sent through our
cache-drain:
1ssh pipe.pico.sh sub cache-drain
During development, it was very easy for us to test this system because we can just clear any HTTP cache through the topic:
1echo 'erock-neovimcraft' | ssh pipe.pico.sh pub cache-drain
That's it!