Merge ~brad-marshall/charm-grafana/+git/grafana-charm:http-proxy-install into ~prometheus-charmers/charm-grafana:master

[Brad Marshall]

Added the ability to use a http_proxy for the install file option. I've tested this locally and ensured it went via the proxy.

[Paul Gear (paulgear)]

LGTM

review: Approve

diff --git a/config.yaml b/config.yaml
index 60f282e..f5c4e6c 100644
--- a/config.yaml
+++ b/config.yaml
@@ -127,3 +127,8 @@ options:
       Comma separated list of http(s) URLs where grafana plugin tarballs can be found.
       Example:
         install_plugins: http://my.company.com/packages/grafana/plugins/plugin-panel.tar.gz
+  http_proxy:
+    default: ""
+    type: string
+    description: |
+      Proxy URL to use for install_file
diff --git a/reactive/grafana.py b/reactive/grafana.py
index 91f813f..d3b90bc 100644
--- a/reactive/grafana.py
+++ b/reactive/grafana.py
@@ -44,12 +44,21 @@ def install_packages():
     config = hookenv.config()
     install_opts = ('install_sources', 'install_keys')
     hookenv.status_set('maintenance', 'Installing grafana')
+
+    if config.get('http_proxy'):
+        proxy = {"http": config.get('http_proxy'),
+                 "https": config.get('http_proxy'),
+                 }
+    else:
+        proxy = {}
+
     if config.changed('install_file') and config.get('install_file', False):
         hookenv.status_set('maintenance', 'Installing deb pkgs')
         fetch.apt_install(GRAFANA_DEPS)
         pkg_file = '/tmp/grafana.deb'
         with open(pkg_file, 'wb') as f:
-            r = requests.get(config.get('install_file'), stream=True)
+            r = requests.get(config.get('install_file'), stream=True,
+                             proxies=proxy)
             for block in r.iter_content(1024):
                 f.write(block)
         subprocess.check_call(['dpkg', '-i', pkg_file])