ruby gem to auto reload config files during runtime - ruby

Question

I am looking for a ruby gem ( or a idea to develop one) which can refresh config files(yaml) during runtime. So that I can store in variable and use them.

Answer 1

There's a config object in Configurabilty (disclosure: I'm the author) which you can use either on its own, or as part of the Configurability mixin. From the documentation:
Configurability also includes Configurability::Config, a fairly simple
configuration object class that can be used to load a YAML configuration file,
and then present both a Hash-like and a Struct-like interface for reading
configuration sections and values; it's meant to be used in tandem with Configurability, but it's also useful on its own.
Here's a quick example to demonstrate some of its features. Suppose you have a
config file that looks like this:
---
database:
development:
adapter: sqlite3
database: db/dev.db
pool: 5
timeout: 5000
testing:
adapter: sqlite3
database: db/testing.db
pool: 2
timeout: 5000
production:
adapter: postgres
database: fixedassets
pool: 25
timeout: 50
ldap:
uri: ldap://ldap.acme.com/dc=acme,dc=com
bind_dn: cn=web,dc=acme,dc=com
bind_pass: Mut#ge.Mix#ge
branding:
header: "#333"
title: "#dedede"
anchor: "#9fc8d4"
You can load this config like so:
require 'configurability/config'
config = Configurability::Config.load( 'examples/config.yml' )
# => #<Configurability::Config:0x1018a7c7016 loaded from
examples/config.yml; 3 sections: database, ldap, branding>
And then access it using struct-like methods:
config.database
# => #<Configurability::Config::Struct:101806fb816
{:development=>{:adapter=>"sqlite3", :database=>"db/dev.db", :pool=>5,
:timeout=>5000}, :testing=>{:adapter=>"sqlite3",
:database=>"db/testing.db", :pool=>2, :timeout=>5000},
:production=>{:adapter=>"postgres", :database=>"fixedassets",
:pool=>25, :timeout=>50}}>
config.database.development.adapter
# => "sqlite3"
config.ldap.uri
# => "ldap://ldap.acme.com/dc=acme,dc=com"
config.branding.title
# => "#dedede"
or using a Hash-like interface using either Symbols, Strings, or a mix of
both:
config[:branding][:title]
# => "#dedede"
config['branding']['header']
# => "#333"
config['branding'][:anchor]
# => "#9fc8d4"
You can install it via the Configurability interface:
config.install
Check to see if the file it was loaded from has changed since you
loaded it:
config.changed?
# => false
# Simulate changing the file by manually changing its mtime
File.utime( Time.now, Time.now, config.path )
config.changed?
# => true
If it has changed (or even if it hasn't), you can reload it, which automatically re-installs it via the Configurability interface:
config.reload
You can make modifications via the same Struct- or Hash-like interfaces and write the modified config back out to the same file:
config.database.testing.adapter = 'mysql'
config[:database]['testing'].database = 't_fixedassets'
then dump it to a YAML string:
config.dump
# => "--- \ndatabase: \n development: \n adapter: sqlite3\n
database: db/dev.db\n pool: 5\n timeout: 5000\n testing: \n
adapter: mysql\n database: t_fixedassets\n pool: 2\n timeout:
5000\n production: \n adapter: postgres\n database:
fixedassets\n pool: 25\n timeout: 50\nldap: \n uri:
ldap://ldap.acme.com/dc=acme,dc=com\n bind_dn:
cn=web,dc=acme,dc=com\n bind_pass: Mut#ge.Mix#ge\nbranding: \n
header: \"#333\"\n title: \"#dedede\"\n anchor: \"#9fc8d4\"\n"
or write it back to the file it was loaded from:
config.write

Answer 2

Using for example Watchr or Guard you can monitor files and act on changes to them.
The actual action to take when a file changes depends entirely on your specific setup and situation, so you're on your own there. Or you need to provide more information.