vmalert: support configuration file for notifiers
* vmalert notifiers now can be configured via file
see https://docs.victoriametrics.com/vmalert.html#notifier-configuration-file
* add support of Consul service discovery for notifiers config
see https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1947
* add UI section for currently loaded/discovered notifiers
* deprecate `-rule.configCheckInterval` in favour of `-configCheckInterval`
* add ability to suppress logs for duplicated targets for notifiers discovery
* change behaviour of `vmalert_alerts_send_errors_total` - it now accounts
for failed alerts, not HTTP calls.
* vmalert: remove `vmalert_execution_duration_seconds` metric
The summary for `vmalert_execution_duration_seconds` metric gives no additional
value comparing to `vmalert_iteration_duration_seconds` metric.
* vmalert: update config reload success metric properly
Previously, if there was unsuccessfull attempt to reload config and then
rollback to previous version - the metric remained set to 0.
* vmalert: add Grafana dashboard to overview application metrics
* docker: include vmalert target into list for scraping
* vmalert: extend notifier metrics with addr label
The change adds an `addr` label to metrics for alerts_sent and alerts_send_errors
to identify which exact address is having issues.
The according change was made to vmalert dashboard.
* vmalert: update documentation and docker environment for vmalert's dashboard
Mention Grafana's dashboard in vmalert's README in a new section #Monitoring.
Update docker-compose env to automatically add vmalert's dashboard.
Update docker-compose README with additional info about services.
* app/vmalert: support multiple notifier urls (#584)
User now can set multiple notifier URLs in the same fashion
as for other vmutils (e.g. vmagent). The same is correct for
TLS setting for every configured URL. Alerts sending is done
in sequential way for respecting the specified URLs order.
* app/vmalert: add basicAuth support for notifier client (#585)
The change adds possibility to set basicAuth creds for notifier
client in the same fasion as for remote write/read and datasource.
app/vmalert: Support custom URL for alerts source
Add flag `external.alert.source` for configuring custom URL
for alert's source. This may be handy to re-point default source
URL to other systems like Grafana.
Updates #517
The change introduces new entity `manager` which replaces
`watchdog`, decouples requestHandler and groups. Manager
supposed to control life cycle of groups, rules and
config reloads.
Groups export an ID method which returns a hash
from filename and group name. ID supposed to be unique
identifier across all loaded groups.
Some tests were added to improve coverage.
Bug with wrong annotation value if $value is used in
templates after metrics being restored fixed.
Notifier interface was extended to accept context.
New set of metrics was introduced for config reload.
* Initial rules evaluation support.
Rules are now store alerts state in private field `alerts`. Every evaluation updates
the alerts and state. Every unique metric received from datastore represents a unique alert,
uniqueness is guaranteed by hashing ordered labelset.
* merge with master
* cleanup
* support endAt parameter as 3*evaluationInterval for active alerts
* make golint happy
