Update README

README.md

@@ -1,2 +1,86 @@
 # JIRAlert
-JIRA integration for Prometheus Alertmanager
+JIRA integration for [Prometheus Alertmanager](https://github.com/prometheus/alertmanager).
+
+## Overview
+
+JIRAlert implements Alertmanager's webhook HTTP API and creates highly configurable JIRA issues when notified. One issue
+is created per distinct group key — as defined by the [`group_by`](https://prometheus.io/docs/alerting/configuration/#<route>)
+parameter of Alertmanager's `route` configuration section — but not closed when the alert is resolved. The expectation
+is that a human will look at the issue, take any necessary action, then close it.  If no human interaction is necessary
+then it should probably not alert in the first place.
+
+If a corresponding JIRA issue already exists but is resolved, it is reopened. A JIRA transition must exist between the
+resolved state and the reopened state — as defined by `reopen_state` — or reopening will fail. Optionally a "won't
+fix" resolution — defined by `wont_fix_resolution` — may be defined: a JIRA issue with this resolution will not be
+reopened by JIRAlert.
+
+## Usage
+
+Get JIRAlert, either as a [packaged release](https://github.com/alin-sinpalean/jiralert/releases) or build it yourself:
+
+```
+$ go get github.com/alin-sinpalean/jiralert/cmd/jiralert
+```
+
+then run it from the command line:
+
+```
+$ jiralert
+```
+
+Use the `-help` flag to get help information.
+
+```
+$ jiralert -help
+Usage of jiralert:
+  -config string
+      The JIRAlert configuration file (default "config/jiralert.yml")
+  -listen-address string
+      The address to listen on for HTTP requests. (default ":2197")
+  [...]
+```
+
+## Testing
+
+JIRAlert expects a JSON object from Alertmanager. The format of this JSON is described in the [Alertmanager
+documentation](https://prometheus.io/docs/alerting/configuration/#<webhook_config>) or, alternatively,
+in the [Alertmanager GoDoc](https://godoc.org/github.com/prometheus/alertmanager/template#Data).
+
+To quickly test if JIRAlert is working you can run:
+
+```bash
+$ curl -H "Content-type: application/json" -X POST \
+  -d '{"receiver": "jira-ab", "status": "firing", "alerts": [{"status": "firing", "labels": {"alertname": "TestAlert", "key": "value"} }], "groupLabels": {"alertname": "TestAlert"}}' \
+  http://localhost:2197/alert
+```
+
+## Configuration
+
+The configuration file is essentially a list of receivers matching 1-1 all Alertmanager receivers pointing to JIRAlert
+plus defaults (also as a receiver) and a pointer to the template file.
+
+Each receiver must have a unique name (matching the Alertmanager receiver name), JIRA API access fields (URL, username
+and password), a handful of required issue fields (such as the JIRA project and issue summary), some optional issue
+fields (e.g. priority) and a `fields` map for other (standard or custom) JIRA fields. Most of these may use [Go
+templating](https://golang.org/pkg/text/template/) to generate the actual field values based on the contents of the
+Alertmanager notification. The exact same data structures and functions as those defined in the [Alertmanager template
+reference](https://prometheus.io/docs/alerting/notifications/) are available in JIRAlert.
+
+## Alertmanager configuration
+
+To enable Alertmanager to talk to JIRAlert you need to configure a webhook in Alertmanager. You can do that by adding a
+webhook receiver to your Alertmanager configuration. 
+
+```yaml
+receivers:
+- name: 'jira-ab'
+  webhook_configs:
+  - url: 'http://localhost:2197/alert'
+    # JIRAlert ignores resolved alerts, avoid unnecessary noise
+    send_resolved: false
+```
+
+## License
+
+JIRAlert is licensed under the [MIT License](https://github.com/alin-sinpalean/jiralert/blob/master/LICENSE).
+Copyright (c) 2016, Alin Sinpalean