The unix process model is a simple and powerful abstraction for running server-side programs. Applied to web apps, the process model gives us a unique way to think about dividing our workloads and scaling up over time.

Mark Mayo describes how the profession of sysadmin is changing:

The dreaded “wedged Mongrel” - your app server stuck on one request, with others piling up, waiting infinitely for it to come free - is a problem all production Rails apps face sooner or later. The solution most commonly used is to restart the app servers frequently, via something like Monit, or just on a cron job.

The unix shell (bash) and remote login (ssh) are centerpieces of the server and app deployment process. While building Heroku, however, Orion and I became aware that these tools are pretty far out of step with modern, agile development practices.

The ability to mount a remote filesystem and read and write to it is something everyone has wanted to do for a long, long time. SMB was an ok solution in the 90s, at least for users with minimal needs. Another dinosaur that we all love to hate is NFS. Despite its synchronization and locking issues, NFS actually works pretty well. But it’s a real headache when it comes to firewalls and certainly is not suitable for use over the open internet. Sysadmins will always tell you “don’t use NFS, it sucks,” but when you ask for a better alternative they just shrug and hastily excuse themselves from the conversation.

And now for one of my favorite bits of black magic from the unix poweruser’s toolkit: ssh tunnels.

Like most good tricks, this one is simple. It lets you bounce TCP traffic through an ssh connection. This is handy in a variety of situations, but the one I’ve used it most often for is to access a website which is available only inside of a corporate LAN. If you’ve got external ssh access, you can set up a tunnel that will let you point your browser at a local port to access that site.