new: [postgres-alpine] added charm.

postgres-alpine/hooks/postgres_database-relation-joined

@@ -0,0 +1,21 @@
+#!/bin/bash
+
+## When writing relation script, remember:
+##  - they should be idempotents
+##  - they can be launched while the dockers is already up
+##  - they are launched from the host
+##  - the target of the link is launched first, and get a chance to ``relation-set``
+##  - both side of the scripts get to use ``relation-get``.
+
+USER=$(relation-get user)
+PASSWORD="$(relation-get password 2>/dev/null)" || PASSWORD="$(gen_password)"
+
+config-add "\
+services:
+  $TARGET_CHARM_NAME:
+    environment:
+      POSTGRES_USER: $USER
+      POSTGRES_PASSWORD: $PASSWORD
+"
+
+relation-set password "$PASSWORD"

postgres-alpine/metadata.yml

@@ -0,0 +1,4 @@
+
+docker-image: postgres:9.3-alpine
+data-resources:
+  - /var/lib/postgresql/data