Merge pull request #8 from juju-solutions/java

Refactors to support dynamic Java charm binding

layer.yaml

@@ -1,5 +1,5 @@
 repo: git@github.com:juju-solutions/layer-hadoop-client.git
-includes: ['layer:basic', 'interface:hadoop-plugin']
+includes: ['layer:basic', 'interface:hadoop-plugin', 'interface:java']
 defines:
   packages:
     description: >

metadata.yaml

@@ -12,3 +12,7 @@ tags: ["bigdata", "hadoop"]
 provides:
   hadoop:
     interface: hadoop-plugin
+    scope: container
+  java:
+    interface: java
+    scope: container

reactive/hadoop_client.py

@@ -1,5 +1,5 @@
 # pylint: disable=unused-argument
-from charms.reactive import when, when_not
+from charms.reactive import when, when_not, when_not_all, is_state
 from charmhelpers.core import hookenv
 from charms import layer
 
@@ -12,11 +12,22 @@ def report_ready(hadoop):
         hookenv.status_set('active', 'Ready')
 
 
-@when_not('hadoop.joined')
+@when_not_all('hadoop.joined', 'java.ready')
 def report_blocked():
     cfg = layer.options('hadoop-client')
     if not cfg.get('silent'):
-        hookenv.status_set('blocked', 'Waiting for relation to Hadoop Plugin')
+        missing = []
+        if not is_state('hadoop.joined'):
+            missing.append('relation to Hadoop Plugin')
+        if not is_state('java.ready'):
+            missing.append('Java')
+        missing = ' & '.join(missing)
+        hookenv.status_set('blocked', 'Waiting for {}'.format(missing))
+
+
+@when('hadoop.joined', 'java.ready')
+def proxy_java(hadoop, java):
+    hadoop.set_java_info(java.java_home(), java.java_version())
 
 
 @when('hadoop.joined')