Modify the unix script. (#3059)

Modifies the line containing `CLASSPATH=` in generated unix script file and add entries for

1. $APP_HOME/ext-lib/* - To be used to add extra jars to classpath
2. $APP_HOME/config - To be used to add custom application.conf

Author: chetanmeh

build.gradle

@@ -10,4 +10,30 @@ buildscript {
 subprojects {
     apply plugin: 'scalafmt'
     scalafmt.configFilePath = gradle.scalafmt.config
+
+    afterEvaluate {
+        if (project.plugins.hasPlugin('application')
+                && project.plugins.hasPlugin('scala')) {
+            startScripts {
+                doLast {
+                    unixScript.text = configureUnixClasspath(unixScript)
+                }
+            }
+        }
+    }
+}
+
+def configureUnixClasspath(File script) {
+    script
+        .readLines()
+        .collect { line ->
+            // Looking for the line that starts with CLASSPATH=
+            line = line.replaceAll(~/^CLASSPATH=.*$/) { original ->
+
+                // Get original line and append it
+                // with the configuration directory.
+                original += ':$APP_HOME/ext-lib/*:$APP_HOME/config'
+            }
+        }
+        .join('\n')
 }

docs/spi.md

@@ -62,3 +62,15 @@ Since SPI implementations are loaded from the classpath, and a specific implemen
 * Include all implementations, and only use the specified implementations.
 * Include some combination of defaults and alternative implementations, and use the specified implementations for the alternatives, and default implementations for the rest.
 
+## Including the implementation
+
+Base openwhisk docker images provide 2 extension points in the classpath for including the implementation.
+
+### Application Jars
+
+The application jars can be added to `$APP_HOME/ext-lib` for e.g. in `openwhisk/controller` image the implementation jars can be added to `/controller/ext-lib` and for `openwhisk/invoker` they can be added to `/invoker/ext-lib`.
+
+### Application Configuration
+
+The configuration files can be added to `$APP_HOME/config`.
+