superwatcher
v0.2.0
Published
Watch a GiT repository for changes
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Readme
Why Care
Sure, you can watch for local file changes and react to those with a
script, but can you watch for remote file changes in a git
repository?
What It Does
superwatcher
:
- watches
git
repositories for you - keeps those repositores up to date
- triggers an update hook script on each update
With this simple tool combined with forever
you can create an auto updating, auto restarting server. All you need to
do to autodeploy to as many nodes as you like is git push
.
Unlike pretty much every other autodeploy tool, superwatcher
doesn't
assume any specific workflow, you can watch any repository and branch
you like, triggering an optional script after each update. Since that is
just a shell script, you can do what you like
What It Is
superwatcher
is a command line program that leverages good old cron
to create a series of repository watchdogs.
Seems like folks are generally in love with git hooks, which works great
except when one of your nodes is down and misses the hook and jams up
the works. Using hooks is a push method. Using cron
is a pull
method. The benefit is that nodes that are down will eventually catch up
as they pull in new changes. Self healing.
Cron is also nice in that is:
- survives reboots
- is already there and doesn't require installing another daemon as root
The watchdogs will leave configuration in ~/.superwatcher
, just as
plain text so you can hack and poke as you see fit.
How To Use It
npm install -g superwatcher
Yep, you'll need node.
superwatcher --help
...get the lay of the land
Update Triggers
These are just shell scripts, in the root of each watched repository.
Hooks wrap the auto update sequence, which goes like this:
- Ask the git remote if there are missing local changes
- If no, go back to sleep
- If yes, run the
superwatcher_before_update
currently on disk, this will be the prior version, not the one incoming from the remote - Use git to fetch and reset to the current remote revision
- Run the
superwatcher_after_update
currently on disk, this may have been freshly pulled
Environment
Cron is nice, except when it isn't. The exact environment you get in a
cron job isn't always what you would expect, so superwatcher
lets you
set it explicitly. This will be sourced before every autoupdate
sequence, and lets you do fun stuff like pick the right node
, set
PATH
, etc.
Enough Already!
Ok, here is how you use the thing:
npm install -g superwatcher
superwatcher init
superwatcher watch git://github.com/wballard/superwatcher.demo.git ~/demo
superwatcher environment ~/demo/environment
superwatcher start
At this point, everything should run. All you need to do in order to push changes is update the git repository, which is ... well, you'll need to switch to your own repository :).
You can see what is going on with:
superwatcher info
And shut the whole thing down with:
superwatcher stop
Make a Sandwich
To get a super simple, self updating server, combine superwatcher
with
forever --watch --watchDirectory
. This will give you auto update, and self restart on
update.