feat(ui): allow acknowledging alerts using short lived silences

docs/CONFIGURATION.md

@@ -229,6 +229,70 @@ setting multiple Alertmanager servers. For cases where only a single server
 needs to be configured without a config file see
 [Simplified Configuration](#simplified-configuration).
 
+### Alert acknowledgement
+
+Prometheus Alertmanager allows alerts to be in 3 states:
+
+- `active` - when alert is firing
+- `suppressed` - when alert is either silenced by a
+  [silence rule](https://prometheus.io/docs/alerting/alertmanager/#silences) or
+  inhibited by another alert using
+  [inhibition rules](https://prometheus.io/docs/alerting/alertmanager/#inhibition)
+- `unprocessed` - initial state for new alerts before they are checked against
+  all silence rules so Alertmanager doesn't yet know if the alert should be
+  `active` or `supported`
+
+A silence rule can be used to mark an alert as acknowledged and being worked on.
+To simplify creating of such silences karma provides a one click button that
+will create a silence matching alert group it was clicked for.
+`alertAcknowledgement` allows to enable this feature and customize it's
+configuration.
+Syntax:
+
+```YAML
+alertAcknowledgement:
+  enabled: bool
+  duration: duration
+  author: string
+  commentPrefix: string
+```
+
+- `enabled` - setting it to true will enable creation of short lived
+  acknowledgement silences.
+- `duration` - duration for acknowledgement silences, value is a string in
+  [time.Duration](https://golang.org/pkg/time/#ParseDuration) format.
+- `author` - default author for acknowledgement silences. If user set the
+  author field on the silence form then that value will be used instead.
+- `commentPrefix` - a string that will be added as a prefix to autogenerated
+  silence comment (optional).
+
+Defaults:
+
+```YAML
+alertAcknowledgement:
+  enabled: false
+  duration: 15m0s
+  author: karma
+  commentPrefix: ACK!
+```
+
+A common problem is setting a correct duration for the silence.
+If set for too short it can expire before the issue is resolved, and will
+require re-silencing all the alerts.
+If set for too long it mask the same problem reoccurring in the future. This
+requires user to expire the silence once the issue is resolved.
+
+[kthxbye](https://github.com/prymitive/kthxbye) is a tiny daemon that can help
+with managing short lived acknowledged silences. It will continuously extend
+short lived acknowledgement silences if there are alerts firing against those
+silences, which means that the user doesn't need to worry about setting proper
+duration for such silences.
+To use it run an instance of kthxbye with every alertmanager instance or
+cluster and configure it to use the same comment prefix as `commentPrefix`.
+With this setup when user clicks to acknowledge an alert karma will create
+a short lived silence and kthxbye will keep that silence in Alertmanager
+until there are no alerts matching it, meaning that the issue was resolved.
+
 ### Annotations
 
 `annotations` section allows configuring how alert annotation are displayed in