Configuration

Contents

• Modes of Configuration
• Order of Precedence
• Data Structure

Modes of Configuration

cmr-service-bridge is configured in several ways:

• Configuration file (see resources/config/cmr-opendap/config.edn) - this is generally for providing more-or-less static defaults.
• Java system properties - provided either with the -Dsome.prop.name=value as a command line option, or in the project.clj file with :jvm-opts=["-Dcmr.some.prop.name=value"]. This is the recommended way to set values for local development environments. Note that only property names starting with “cmr.” will be recognized. Also: configuration will be nested under keys created from the property name, so the above example would be available as {:cmr {:some {:prop {:name "value"}}}}. Values that can be parsed as integers are converted to integers in the resulting configuration data structure.
• Environment variables - this is the recommended way to override configuration values in different deployment environments. Environment variables must be prefixed with CMR_, HTTPD_, or LOGGING_. Variables names are split on underscores in the same way that system properties are split on the period character. As such, when executing CMR_SOME_PROP_NAME=value lein run, the configuration data will have the same nested data as show above, namely: {:cmr {:some {:prop {:name "value"}}}}. As with system property conifguration, environment variables that can be based as integers, are.

Order of Precedence

1. Environment variables reign supreme: they override all other means of configuration.
2. Next are options set, e.g., via the command line with java or in lein’s :jvm-opts; these take precedence over entries made in the configuration file.
3. Finally, anything set in the configuration file that wasn’t specified in the above will be interpreted.

Data Structure

Once environment variables, JVM options system properties, and the EDN config file have all been parsed, they are merged (using deep merge) into a hash map something like the following:

 {:cmr
   {:opendap
   	 {:public
   	 	{:protocol ""
   	 	 :host ""
   	     :port nnn}
   	  :host ""
   	  :port nnn
   	  :relative
   	    {:root
   	      {:url ""}}
   	  :version "x.y.z"}}
   {:access
     {:control
     	{:protocol ""
     	 :host ""
     	 :port nnn}}}
   {:echo
     {:rest
     	{:protocol ""
     	 :host ""
     	 :port nnn
     	 :context ""}}}
   {:ingest
     {:protocol ""
 	  :host ""
 	  :port nnn}}
   {:search
     {:protocol ""
 	  :host ""
 	  :port nnn}}}