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Comment by csomar | Hacker News Reader

> i have very high and unusual standards,

> this script runs every minute on a cronjob, and rebuilds my site if the git repo has been updated.

He is pulling the git repo 525,600 times a year for the few commits he'll be making in that year... I guess that explains the "unusual" word?

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git fetch is basically just one string comparison if there are no new commits [0], I don’t think it’s as costly as you make it sound.

[0] https://stackoverflow.com/a/44476803

I guess that would have been fine if we didn't have alternatives (ie: callbacks). He is already running a web server, so he could listen through that for updates.

If he breaks the server, then a callback/webhook notification for the fix won't work either.

If you want to use a callback for this I'd recommend still polling periodically anyway.

Problem with self-hosting though, if his server breaks, so does the callbacks.

It might be a string comparison, but one of the strings usually comes from a remote server, which can be costly.

Maybe, but Git has hooks. The author could deploy on push to do it only when needed, and immediately when relevant, rather than having to decide on a trade-off between immediacy and doing a lot of useless operations.

Obviously, this approach might not work for everyone, but I like to self-host my repos and use a git hook (post-receive) like this:

  #!/bin/sh
  BUILDDIR=/home/buildhook/.ib-build
  BUILD=`grep build |cut -d" " -f2`
  if [ -n "$BUILD" ]
  then
          touch $BUILDDIR/$BUILD
  fi

And then the buildhook user has a job that runs every minute by cron:

  #!/bin/sh
  BUILDDIR=/home/buildhook/.ib-build
  BUILD=`ls -t $BUILDDIR | head -1`
  if [ -n "$BUILD" ]
  then
          rm -f $BUILDDIR/$BUILD
          (
          echo Building $BUILD on builder...
          ssh builder time ./build $BUILD
          ) 2>&1 | mail -s "Building $BUILD on builder" build@example.com
  fi

For my use case, on this repo, pushing to a branch with the word "build" in its name will trigger a build of that commit, which builds and packages it into a dpkg, and the build server hosts a private apt repository so I can just `apt-get update; apt-get install blah` on all the servers.

An alternative strategy is pushing to a different repo on a build server, etc.

Unusual would be crazy in this circumstance.

Tell, don't ask.

you're making a lot of assumptions about how my deployment works here!

my git repositories are all on the same server that hosts my website - git is not doing a remote fetch - it's a local fetch, which makes it basically instantaneous.

even if it were a remote fetch, i would be fine with it. 525,600 http requests per year is less wasteful than NetworkManager's heartbeat (which defaults to 1 heartbeat request per _30 seconds_ on Arch)

for some context, a stock nginx server with 8 cpus can handle ~500k+ http requests _per second_.

Did you remember that number from Rent?

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