use env vars in geoserver config

app/services/geo_concerns/delivery/geoserver.rb

@@ -1,6 +1,7 @@
 require 'active_support/core_ext/hash/indifferent_access'
 require 'rgeoserver'
 require 'yaml'
+require 'erb'
 
 module GeoConcerns
   module Delivery
@@ -15,7 +16,7 @@ class Geoserver
 
       def initialize
         begin
-          data = File.read(Rails.root.join('config', 'geoserver.yml'))
+          data = ERB.new(File.read(Rails.root.join('config', 'geoserver.yml'))).result
           @config = YAML.load(data)['geoserver'].with_indifferent_access.freeze
         rescue Errno::ENOENT
           @config = DEFAULT_CONFIG

lib/generators/geo_concerns/templates/config/geoserver.yml

@@ -1,17 +1,15 @@
 geoserver:
   # Set to the REST API for the GeoServer
-  url: "http://localhost:8181/geoserver/rest"
+  url: <%= ENV['GEOSERVER_URL'] || "http://192.168.99.100:8181/geoserver/rest" %>
   # Optional user/password, set to false to disable
-  user: "admin"
-  password: "geoserver"
-  # Set to your GWC server, or "builtin" for the one bundled with GeoServer
-  geowebcache_url: "builtin"
+  user: <%= ENV['GEOSERVER_USER'] || "admin" %>
+  password: <%= ENV['GEOSERVER_PASSWORD'] || "geoserver" %>
+  # Set to your GWC server, or "builtin" for the one bundled with GeoServer  
+  geowebcache_url: <%= ENV['GEOSERVER_GWC_URL'] || "builtin" %>""
 
   # RestClient:
   restclient:
-    # Set to false to disable or stdout/stderr or 'filename.out'
     logfile: stderr
-    # Timeout (in seconds)
     timeout: 300
     # Open Timeout (in seconds)
     open_timeout: 60