by Ruben Fonseca (rubenfonseca)

Online rails configuration generator using etcd as source data.

• Bring the power of etcd live changes to your Rails app
• Everytime there's a change on an etcd dir, your Rails config files are updated and processes are restarted
• Written in Go so no runtime dependency on your production servers
• Extendable system to support more rendererers (turns etcd data into files) and reloaders (reloads Rails processes)
• Currently supported renderers:
  • YAML - renderes the etcd data to a .yml file
• Currently supported reloaders:
  • Touch - touches tmp/restart.txt for passenger compatible servers.

$ go install github.com/rubenfonseca/rails-configd
$ rails-configd -h

First you have to set the data on your etcd cluster. Let's try to configure the database on our production rails app.

$ export DIR=rails_app01/database/production
$ etcdctl set $DIR/host lan.db01.example.com
$ etcdctl set $DIR/adapter pg
$ etcdctl set $DIR/database db01
$ etcdctl set $DIR/username dbuser

Then, next to each Rails app, you should run a rails-configd daemon:

$ rails-configd --etcd http://localhost:4001 --etcd-dir /rails_app01 \
                --renderer yaml --yaml-file config/database.yml \
                --reloader touch

This will read from etcd under /rails_app01 directory and build the config/database.yml file. After this, any change to a key under the etcd-dir directory will trigger the generation of a new database.yml file, and reload the rails server by touching tmp/restart.txt.

I believe this daemon does only one thing and does it right. I don't want to add another responsability to Rails. Also, since this is written in Go, you can distribute a binary to all your platforms with no runtime dependencies (aka: bundle install...)

I also do :) Then the sollution is to run one rails-configd daemon for each file. Each daemon will read form a different etcd directory, and you can control the output file with the param yaml-file. Don't worry about resources, go daemons like this use very little memory :-)

Then pachtes are welcome :) There's a reloader interface on the code that you can implement with your own reloading method!

rails-configd uses semantic versioning.

rails-configd is under MIT license. See the LICENSE file for details.