Merge ~axino/juju-introspection-proxy-charm/+git/juju-introspection-proxy-charm:axino into juju-introspection-proxy-charm:master

[Junien F]

[Barry Price (barryprice)]

Looks good to me, +1

review: Approve

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..edb8bcd
--- /dev/null
+++ b/README.md
@@ -0,0 +1,14 @@
+Relate this charm to any Juju application to make Juju introspection data
+available over HTTP (for consumption by prometheus, for example).
+
+You will need to build the go binary from
+https://github.com/axw/juju-introspection-proxy and specify it as the "binary"
+resource, for example :
+
+```
+$ juju deploy juju-introspection-proxy --resource binary=/path/to/juju-introspection-proxy
+$ juju add-relation my-awesome-application juju-introspection-proxy
+$ juju expose juju-introspection-proxy
+```
+
+Metrics will be available at ```http://<unit_ip>:19090/metrics```.
diff --git a/config.yaml b/config.yaml
new file mode 100644
index 0000000..2e3969e
--- /dev/null
+++ b/config.yaml
@@ -0,0 +1,6 @@
+options:
+  port:
+    type: int
+    default: 19090
+    description: "Port to listen for connections on"
+
diff --git a/layer.yaml b/layer.yaml
new file mode 100644
index 0000000..102cf18
--- /dev/null
+++ b/layer.yaml
@@ -0,0 +1 @@
+includes: ['layer:basic']  # if you use any interfaces, add them here
diff --git a/metadata.yaml b/metadata.yaml
new file mode 100644
index 0000000..6c25bd0
--- /dev/null
+++ b/metadata.yaml
@@ -0,0 +1,20 @@
+name: juju-introspection-proxy
+summary: A proxy to the Juju introspection metrics
+maintainer: Junien Fridrick <[e-mail]>
+description: |
+  A proxy to the Juju introspection metrics
+tags:
+  - monitoring
+  - performance
+subordinate: true
+series:
+  - xenial
+requires:
+  container:
+    interface: juju-info
+    scope: container
+resources:
+  binary:
+    type: file
+    filename: juju-introspection-proxy
+    description: the Juju introspection proxy binary
diff --git a/reactive/juju_introspection_proxy.py b/reactive/juju_introspection_proxy.py
new file mode 100644
index 0000000..7a5ea6f
--- /dev/null
+++ b/reactive/juju_introspection_proxy.py
@@ -0,0 +1,75 @@
+import os
+import subprocess
+
+from charms.reactive import (
+    set_state,
+    when,
+    when_not,
+)
+
+from charmhelpers.core import (
+    hookenv,
+    templating,
+)
+
+INSTALL_ROOT = "/srv/juju-introspection-proxy"
+INSTALL_PATH = os.path.join(INSTALL_ROOT, 'bin', 'juju-introspection-proxy')
+
+
+@when_not('juju-introspection.installed')
+def install_juju_introspection():
+    ''' Install the proxy application '''
+
+    try:
+        binary = hookenv.resource_get('binary')
+    except Exception:
+        message = 'Error fetching the binary resource.'
+        hookenv.log(message)
+        hookenv.status_set('blocked', message)
+        return
+    if not binary:
+        message = 'Missing binary resource.'
+        hookenv.log(message)
+        hookenv.status_set('blocked', message)
+        return
+
+    install = ['install', '-v', '-D', binary, INSTALL_PATH]
+    subprocess.check_call(install)
+
+    # Create a systemd unit file, and open the port.
+    port = hookenv.config()['port']
+    write_systemd_unit(port)
+    subprocess.check_call(['systemctl', 'enable', 'juju-introspection'])
+    subprocess.check_call(['systemctl', 'start', 'juju-introspection'])
+    hookenv.open_port(port)
+    hookenv.status_set('active', 'serving metrics')
+    set_state('juju-introspection.installed')
+
+
+@when('config.changed.port')
+def update_systemd_unit():
+    config = hookenv.config()
+    new_port = config['port']
+    old_port = config.previous('port')
+
+    write_systemd_unit(new_port)
+    subprocess.check_call(['systemctl', 'daemon-reload'])
+    subprocess.check_call(['systemctl', 'restart', 'juju-introspection'])
+
+    if old_port:
+        hookenv.close_port(old_port)
+    hookenv.open_port(new_port)
+    hookenv.status_set('active', 'serving metrics')
+
+
+def write_systemd_unit(port):
+    listen_addr = ':{}'.format(port)
+    templating.render(
+      'juju-introspection.service',
+      '/etc/systemd/system/juju-introspection.service',
+      {
+        'addr':       listen_addr,
+        'executable': INSTALL_PATH,
+        'unit_name':  hookenv.local_unit(),
+      },
+    )
diff --git a/templates/juju-introspection.service b/templates/juju-introspection.service
new file mode 100644
index 0000000..2400a76
--- /dev/null
+++ b/templates/juju-introspection.service
@@ -0,0 +1,11 @@
+[Unit]
+Description=JujuIntrospection
+
+[Service]
+ExecStart={{executable}} -addr "{{addr}}"
+Environment="JUJU_UNIT_NAME={{unit_name}}"
+Restart=on-failure
+TimeoutSec=300
+
+[Install]
+WantedBy=multi-user.target