Distribute CouchDB as part of a Rails app?

Question

I am working on a Rails project and the Architect has asked me to investigate bundling CouchDB into to application so that it can be deployed by Capistrano across multiple platforms and managed by Rake.

My expectation was that I could set up the Erlang VM on the various environments and then distribute the CouchDB application with Capistrano. However I can't find any option to download CouchDB without the Erlang runtime. I can, however see an option to build CouchDB from source which I assume is platform dependent.

I am new to Erlang and CouchBD, am I missing something? Is there a way to bundle CouchDB into a Rails app and distribute it across multiple platforms?

Answer 1

Have a look at some of the tools for provisioning Rails services (such as passenger_stack). Passenger Stack will download, make and install the ancillary services for your Rails app ... might be something you can adapt or use as a base to install Erlang and CouchDB.

There are a bunch of alternatives to this as well. Deprec contains recipes for provisioning with Capistrano. Essential idea is the same though.

Answer 2

I think you will not find a silver bullet. Distributing Erlang is similar to distributing Ruby; however Ruby has the advantage of being included in many default OS installs.

I know ejabberd has pre-built binaries for many distros. You might investigate how they do it.

The correct solution probably depends on how many "multiple platforms" you are targeting. If it's "Ubuntu 8.04 plus Ubuntu 10.04" that is different from several Linux distros, plus OSX, plus FreeBSD. Typically only open source projects support those many platforms and ideally you can get patches from the community. For internal projects, I have seen teams standardize on a Linux build and use virtualization on Mac/Windows.

But back to your question:

Building from source is a reasonable option. You could build when you deploy, or pre-build for all platforms and then deploy the binaries. Both Erlang and CouchDB use Autoconf which means you can --prefix them to a dedicated location (more-or-less standalone apps). It will take some trial and error but your build script can

1. Platform-specific dependency setup: gcc, make, autoconf, everything you need. apt-get on Ubuntu, yum on RHEL, Macports, whatever you need to get a common platform on your development and deployment system
2. Compile and install the rest using the tools from step 1. Use configure --prefix=/opt/my_software to keep it all in one place. (You can totally uninstall with rm -rf.)

This is an medium-level challenge--mostly trial and error. If possible, work within a build framework such as Rake or Toby's suggestion passenger_stack. Good luck!