keter/README.md
2012-05-06 07:27:10 +03:00

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Deployment system for Yesod (and other Haskell) web apps.
Components:
* Logger: provides a file descriptor to redirect output to. Takes the name of
the app.
* Process: Give it all the information (executable, working directory,
environment, args) for a process, and it will start the process and monitor
it. If the process dies, it will restart. Binds the output to the logger.
Allows you to terminate the process.
* Postgres: Ask it for database information for an app. If no information is
available, it will create a database/user.
* Nginx: Send it commands to add/modify/remove a virtual host. It will write
the config file and reload nginx. Also handles management of the pool of open
ports to be assigned.
* App: Started with a path to an app bundle. Unpacks into a random folder
inside the temp folder, gets a random port, starts a Process, updates Nginx,
and waits for commands. Accepts two commands: reload and terminate.
* Terminate kills the existing process, removes from Nginx, and deletes the
folder.
* Reload gets a new random port, unpacks to a new folder in the temp
folder, starts a Process, waits till the process is "ready" (checks with
an HTTP request)- canceling after a certain timeout.
* If process is not ready within timeout, terminate the new process and
delete the new folder.
* If a process *is* ready, tell Nginx to use the new port, wait some
amount of time (20 seconds?), send a TERM to the old process, wait
some more (1 minute?) and delete the old folder.
* Keter: Delete temp folder, start the Nginx, logger, and port assigner. Start
a new App for each app in the incoming folder. Monitor for file changes in
the incoming folder, and appropriately start a new app, reload an existing app,
or delete an existing app. Also provide a web interface based on logger.