* lib/discovery/consul: update services on the watcher's start
Previously, watcher's start was only initing goroutines for discovery
but not waiting for the first iteration to end. It means first Consul
discovery wasn't returning discovered targets until the next iteration.
The change makes the watcher's start blocking until we get first discovery
iteration done and all registries updated.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* vmalert: remove workarounds for consul SD
Now when consul SD lib properly updates services
on the first start, we don't need workarounds in vmalert.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* lib/discovery/consul: update after review
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* wip
Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
* lib/promscrape: support prometheus-like duration in scrape configs
The change allows to specify duration values like `1d`, `1w`
for fields `scrape_interval`, `scrape_timeout`, etc.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/817#issuecomment-1033384766
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* lib/blockcache: make linter happy
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* lib/promscrape: support prometheus-like duration in scrape configs
* add support for extra fields `scrape_align_interval` and `scrape_offset`;
* support Prometheus duration parsing for `__scrape_interval__`
and `__scrape_duration__` labels;
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* wip
* wip
* docs/CHANGELOG.md: document the feature
Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
* Mention about the ability to configure vmalert notifiers via files in docs/CHANGELOG.md
* Mention about the ability to use Consul service discovery for vmalert notifiers in docs/CHANGELOG.md
* Run `make docs-sync` in order to sync app/vmalert/README.md to docs/vmalert.md
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: check if remoteWrite is configured for replay mode
The purpose of `replay` mode is to backfill results of recording
or alerting rules. So `remoteWrite.url` should be required.
Otherwise, process can fail on attempt to send data.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* Update app/vmalert/main.go
Co-authored-by: Aliaksandr Valialkin <valyala@victoriametrics.com>
When using `vmalert` with older Prometheus versions, the passed
`step=2m` may be parsed by Prometheus with an err: "cannot parse \"2m0s\" to a valid duration".
In order to improve compatibility vmalert will always convert step duration to seconds.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1943
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Service labels like `alertname` or `alertgroup` were attached
after template expanding for `labels` section. Because of this,
labels `alertname` or `alertgroup` weren't available for templating
in `labels` section of alert's definition.
This commit changes the order of labels attaching and adds a test
for verifying these labels availability.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1921
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* vmalert: introduce additional HTTP URL params per-group configuration
The new group field `params` allows to configure custom HTTP URL params
per each group. These params will be applied to every request before
executing rule's expression. Hot config reload is also supported.
Field `extra_filter_labels` was deprecated in favour of `params` field.
vmalert will print deprecation log message if config file contains
the deprecated field.
`params` fields are supported by both Prometheus and Graphite datasource types.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* vmalert: provide more examples for `params` field
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* vmalert: set higher priority for `params` setting
If there would be a conflict between URL params set in `datasource.url` flag
and params in group definition the latter will have higher priority.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
The bump was required for `vmalert` package.
`vmalert` docs now also contain an updated description.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Previously, vmalert would print an err message and set vmalert_config_last_reload_successful=0
only once during a hot reload of a bad config. Such behaviour may result into non noticed
event of a bad config reload attempt
Now, it continues to print error messages and keep vmalert_config_last_reload_successful state
until successful attempt will be made or config state will be rolled back to prev state.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
For a long time notifier.Addr flag was required. The assumption was that vmalert will
be always used for alerting. However, practice shows that some users need only
recording rules. In this case, requirement of notifier.Addr is ambigious.
The change verifies if loaded config contains recording or alerting rules and
if there are corresponding flags set. This is true for initial config load
and hot reload.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
This removes the unneeded level of indirection and improves code readability.
The "prometheus" and "graphite" constants aren't going to change in the future, so there is no sense in hiding them behind constants.
Previously only the lower part of 64-bit hash was used for calculating the offset.
This may give uneven distribution in some cases. So let's use all the available 64 bits from the hash
for calculating the offset.
Prometheus allows to have groups with no rules, so we should support
it in vmalert as well for compatibility reasons.
It is also allowed to hot-reload empty groups by adding or removing rules.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Previously, ID for alert entity was generated without alertname or groupname.
This led to collision, when multiple alerting rules within the same group
producing same labelsets. E.g. expr: `sum(metric1) by (job) > 0` and
expr: `sum(metric2) by (job) > 0` could result into same labelset `job: "job"`.
The issue affects only UI and Web API parts of vmalert, because alert ID is used
only for displaying and finding active alerts. It does not affect state restore
procedure, since this label was added right before pushing to remote storage.
The change now adds all extra labels right after receiving response from the datasource.
And removes adding extra labels before pushing to remote storage.
Additionally, change introduces a new flag `Restored` which will be displayed in UI
for alerts which have been restored from remote storage on restart.
Commit fixes potential race condition when group update
and generating of ID() happens simultaneously.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Regression was introduced during code refactoring. It potentially
could lead to situation when SIGHUP signals were ignored while
vmalert was still busy with initing group manager.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
The extra `/` may cause issues when additional path prefixes
are configured. Also, removing it makes it consistent
with the rest of declarations.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* vmalert: adjust `http.Transport.MaxIdleConns` value accordingly to `http.Transport.MaxIdleConnsPerHost`
`http.Transport.MaxIdleConnsPerHost` setting is controlled by `datasource.maxIdleConnections` flag,
while `http.Transport.MaxIdleConns` is inherited from DefaultTransport and is equal to `100`.
The fix adjusts `http.Transport.MaxIdleConns` value if it is lower than `http.Transport.MaxIdleConnsPerHost`.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* vmauth: adjust `http.Transport.MaxIdleConns` value accordingly to `http.Transport.MaxIdleConnsPerHost`
`http.Transport.MaxIdleConnsPerHost` setting is controlled by `maxIdleConnsPerBackend` flag,
while `http.Transport.MaxIdleConns` is inherited from DefaultTransport and is equal to `100`.
The fix adjusts `http.Transport.MaxIdleConns` value if it is lower than `http.Transport.MaxIdleConnsPerHost`.
Signed-off-by: hagen1778 <roman@victoriametrics.com>
The source link is controlled by `external.url` and `external.alert.source`
flags, in the same way as for alertmanager notifications.
The source link is added to Alerts list view, and specific Alert view.
`omitempty` tag resulted into skipping this param on marshaling,
which was used as a checksum for groups configuration. Since on
config reload checksums are compared before applying changes,
any change to `interval` only didn't trigger config reload.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1641
Signed-off-by: hagen1778 <roman@victoriametrics.com>
* vmalert: add flag to limit the max value for auto-resovle duration for alerts
The new flag `rule.maxResolveDuration` suppose to limit max value for
alert.End param, which is used by notifiers like Alertmanager for alerts auto resolve.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1586
New UI pages:
/ - welcome page with API handlers list;
/groups - list of all rules per group;
/alerts - list of all active alerts;
/groupID/alertID/status - status of the active alert;
* vmalert: allow extra GET params in datasource package
ExtraParams will be added as GET params to every HTTP request made by datasource.
The `roundDigits` param, for example, was substituted by corresponding extra param.
* vmalert: add nocache=1 param for replay process
The `nocache=1` param is VictoriaMetrics specific parameter which prevents it
from caching and boundaries aligning for queries. We set it to avoid cache
pollution in `replay` mode and also to avoid unnecessary time range boundaries
alignment.
* vmalert: mention nocache=1 in replay description
* vmalert: fix bug with unused param
* 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.
* vmalert: allow to disable automatically added path to remote write address via disablePathAppend flag
* docs: update docs to include remoteWrite.disablePathAppend
* vmalert: expose new metrics for tracking number of produced samples during last evaluation
Two new metrics were added to track the number of samples produced during the last evaluation:
* vmalert_recording_rules_last_evaluation_samples
* vmalert_alerting_rules_last_evaluation_samples
The gauge type is used to remain consistent with Prometheus metric
`prometheus_rule_group_last_evaluation_samples` which is on the group level.
However, the counter type was considered as well.
Two metrics instead of one are used to make it easier to separate recording and
alerting rules. It is likely, number of samples produced by recording rules is
more important so people will refer to it more frequently.
The expected usage of the new metric is the following:
```
- alert: RecordingRuleReturnsEmptyResults
expr: sum(vmalert_recording_rules_last_evaluation_samples) by(recording) < 1
annotations:
summary: Recording rule {{$labels.recording}} returns empty results.
Please verify expression correctness.
```
Addresses https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1494
* vmalert: rename `vmalert_alerts_error` to `vmalert_alerting_rules_error` to remain consistent with recording rules metrics
* vmalert: fix mistake with object reuse while parsing response
During the refactoring, the wrong optimisations was applied in
parse function which caused metric fields reset. The change removes
optimisation.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1369
* vmalert: add test to cover multiple metrics in one response
* vmalert: support rules backfilling (aka `replay`)
vmalert can `replay` configured rules in the past
and backfill results via remote write protocol.
It supports MetricsQL/PromQL storage as data source,
and can backfill data to remote write compatible
storage.
Supports recording and alerting rules `replay`. See more
details in README.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/836
* vmalert: review fixes
* vmalert: readme fixes
New flag `-rule.configCheckInterval` defines how often `vmalert` will re-read
config file. If it detects any changes, the config will be reloaded.
This behaviour is turned off by default.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/512
The new setting `extra_filter_labels` may be assigned to group.
If it is, then all rules within a group will automatically filter
for configured labels. The feature is well-described here
https://docs.victoriametrics.com#prometheus-querying-api-enhancements
New setting is compatible only with VM datasource.
* changes vmalert query function
for prometheus rules compatibility its better to use labels as map.
it simplifies template evaluation and allow to ignore can't evaluate field error
because map will return default value.
fixes https://github.com/VictoriaMetrics/operator/issues/243
duplicates map helps to determine wheter extra labels has overriden
labels which make time series unique. It was using a sorted hashed
labels sequence as a key. But hashing algorithm could have collisions,
so it is more convenient to not use hashing at all.
Log message for recording rules duplicates was improved as well.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1293
Starting from v1.56.0 VM supports `round_digits` which allows to limit
the number of digits after the decimal point in response value. The feature
can be used to reduce entropy of produced by recording rules values
and significantly improve the compression. See more details in link below.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/525
Previously, `startGroup` could exit on restore errors despite the
`remoteRead.ignoreRestoreErrors` flag value. Now vmalert checks the
flag value before deciding whether to return error or just log it.
Alerting rules now can return specific error type ErrStateRestore to indicate
whether restore state procedure failed. Such errors were returned and logged
before as well. But now user can specify whether to just log these errors
(remoteRead.ignoreRestoreErrors=true) or to stop the process
(remoteRead.ignoreRestoreErrors=false). The latter is important when VM isn't
ready yet to serve queries from vmalert and it needs to wait.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/1252
* Simplify arguments list for fn `queryDataSource` to improve readbility
* vmalert: adjust `time` param according to rule evaluation interval
With this change, vmalert will start to use rule's evaluation interval
for truncating the `time` param. This is mostly needed to produce consistent
time series with timestamps unaffected by vmalert start time. Now, timestamp
becomes predictable.
Additionally, adjustment is similar to what Grafana does for plotting range graphs.
Hence, recording rule series and recording rule expression plotted in grafana
suppose to become similar in most of cases.
* changes vmalert Querier with per rule querier
it allows to changes some parametrs based on rule setting
for instance - alert type, tenant for cluster version or event endpoint url.
Previously, vmalert used `lastExecTime` timestamp when writing recording rules
to the remote storage. This may be incorrect, if vmalert uses `datasource.lookback` flag,
which means rule's expression will be executed at some moment in the past.
To avoid such situations, vmalert now will use returned timestamp instead of `lastExecTime`.
The major change is adding `sort` directive to docs. For those docs which are copied
from internal packages `sort` is added via makefile command. For the rest it is added
manually since they're updated manually as well.
The rest of changes is connected with markdown formatting. For example, changing headers
in some files (`##` => `#`) makes navigation on .github.io to look better. This especially
useful for `changelog` docs.
Table of contents for `vmctl` is dropped, since we already have it autogenerated on .github.io.
No link changes expected. The corresponding PR to `cluster` branch will be made in follow-up PR.
3s evaluation interval is too small for practical setups. It can result in increased load on datasource.
So it is better to remove it from example config args, which are usually copy-pasted by novice users.
The archive contains the following executables for Windows:
* vmagent
* vmalert
* vmauth
* vmctl
Other components - vmbackup, vmrestore, victoria-metrics - aren't supported for Windows yet
* init implementation for graphite alerts
* adds graphite support for vmalert
* small fix
* changes vmalert graphite api with type
* updates tests
* small fix
* fixes graphite parse
* Fixes graphite from time
On templates validation stage vmalert does not acutally send queries, so for complex
chained expression validation may fail. To avoid this, we add a blank sample in response
so validation can pass successfully. Later, during the rule execution, stub will be replaced
with real `query` function.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/989
The commit adds a support for template function `query`,
`first` and `value`. The function `query` executes
a MetricsQL query for active alerts. In vmalert we
update templates on every evaluation for active alerts
to keep them up to date. With `query` func it may become
a perf issue since it will fire a query on every execution.
We should keep it in mind for now.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/539
The previous implementation treated extra labels (global and rule labels) as
separate label set to returned time series labels. Hence, time series always contained
only original labels and alert ID was generated from sorted labels key-values.
Extra labels didn't affect the generated ID and were applied on the following actions:
- templating for Summary and Annotations;
- persisting state via remote write;
- restoring state via remote read.
Such behaviour caused difficulties on restore procedure because extra labels had to be dropped
before checking the alert ID, but that not always worked. Consider the case when expression
returns the following time series `up{job="foo"}` and rule has extra label `job=bar`.
This would mean that restored alert ID will be always different to the real time series because
of collision.
To solve the situation extra labels are now always applied beforehand and `vmalert` doesn't
store original labels anymore. However, this could result into a new error situation.
Consider the case when expression returns two time series `up{job="foo"}` and `up{job="baz"}`,
while rule has extra label `job=bar`. In such case, applying extra labels will result into
two identical time series and `vmalert` will return error:
`result contains metrics with the same labelset after applying rule labels`
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/870
Label `alertgroup` was introduced in #611 and automatically added to generated
time series. By mistake, this new label wasn't correctly purged on restore event
and affected alert's ID uniqueness. This commit removes `alertgroup` label
in restore function.
https://github.com/VictoriaMetrics/VictoriaMetrics/issues/870
On config reload event `vmalert` reloads configuration for every group. While
it works for simple configurations, the more complex and heavy installations may
suffer from frequent config reloads.
The change introduces the `checksum` field for every group and is set to md5 hash
of yaml configuration. The checksum will change if on any change to group
definition like rules order or annotation change. Comparing the `checksum` field
on config reload event helps to detect if group should be updated.
The groups update is now done concurrently, so reload duration will be limited by
the slowest group now.
Partially solves #691 by improving config reload speed.
* VMAlert start with empty rules dir
There are some applications (operator for instance), that generates alerts configuration at runtime
and vmalert must start correctly without rules to support this behaviour.
Later application will add rules files and send SIGHUP to vmalert,
which will trigger reading rules files and start rules exectuion.
Removing rules files with SIGHUP signal must stop rules execution and
vmalert will wait for new rules.
* imports sorted
* added test cases for empty rules, removed blank line
* fixed imports conflict
* updated tests
* feat: spread load of rule evaluation by group when starting new groups
* review: reduce the resulting diff.
* Update app/vmalert/group.go
Co-authored-by: Roman Khavronenko <hagen1778@gmail.com>
Co-authored-by: Aliaksandr Valialkin <valyala@gmail.com>
Co-authored-by: Roman Khavronenko <hagen1778@gmail.com>
Description for `-rule` flag uses as example specific chars like asterisks
which could be interpreted wrong by different shells. To avoid this, description
now contains quoted flag values.
See also #708
* app/vmalert: extend metrics set exported by `vmalert` #573
New metrics were added to improve observability:
+ vmalert_alerts_pending{alertname, group} - number of pending alerts per group
per alert;
+ vmalert_alerts_acitve{alertname, group} - number of active alerts per group
per alert;
+ vmalert_alerts_error{alertname, group} - is 1 if alertname ended up with error
during prev execution, is 0 if no errors happened;
+ vmalert_recording_rules_error{recording, group} - is 1 if recording rule
ended up with error during prev execution, is 0 if no errors happened;
* vmalert_iteration_total{group, file} - now contains group and file name labels.
This should improve control over specific groups;
* vmalert_iteration_duration_seconds{group, file} - now contains group and file name labels. This should improve control over specific groups;
Some collisions for alerts and recording rules are possible, because neither
group name nor alert/recording rule name are unique for compatibility reasons.
Commit contains list of TODOs for Unregistering metrics since groups and rules
are ephemeral and could be removed without application restart. In order to
unlock Unregistering feature corresponding PR was filed - https://github.com/VictoriaMetrics/metrics/pull/13
* app/vmalert: extend metrics set exported by `vmalert` #573
The changes are following:
* add an ID label to rules metrics, since `name` collisions within one group is
a common case - see the k8s example alerts;
* supports metrics unregistering on rule updates. Consider the case when one rule
was added or removed from the group, or the whole group was added or removed.
The change depends on https://github.com/VictoriaMetrics/metrics/pull/16
where race condition for Unregister method was fixed.
`external.label` flag supposed to help to distinguish alert or recording rules
source in situations when more than one `vmalert` runs for the same datasource
or AlertManager.
* app/vmalert: add retries to remotewrite
Remotewrite pkg now does limited number of retries if write request failed.
This suppose to make vmalert state persisting more reliable.
New metrics were added to remotewrite in order to track rows/bytes sent/dropped.
defaultFlushInterval was increased from 1s to 5s for sanity reasons.
* fix
* wip
* wip
* wip
* fix bits alignment bug for 32-bit systems
* fix mistakenly dropped field
* Fix Auto metrics relabeled errors
* Finalize auto-genenated Labels
* Fix Test Errors
* fix error logs when queue is full
Co-authored-by: xinyulong <xinyulong@kuaishou.com>
* 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.
The change adds no new functionality and aims to move flags definitions
to subpackages that are using them. This should improve readability
of the main function.
app/vmalert: add support for TLS configuration
Add support for TLS optional configuration in a similar fashion to what
is currently supported in other vmutils such as vmagent. TLS
configuration options are distinct for datasource, remoteRead,
remoteWrite as well as notifier.
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
Uniqueness of rule is now defined by combination of its name, expression and
labels. The hash of the combination is now used as rule ID and identifies rule within the group.
Set of rules from coreos/kube-prometheus was added for testing purposes to
verify compatibility. The check also showed that `vmalert` doesn't support
`query` template function that was mentioned as limitation in README.
The feature allows to speed up group rules execution by
executing them concurrently.
Change also contains README changes to reflect configuration
details.
* vmalert: Add recording rules support.
Recording rules support required additional service refactoring since
it wasn't planned to support them from the very beginning. The list
of changes is following:
* new entity RecordingRule was added for writing results of MetricsQL
expressions into remote storage;
* interface Rule now unites both recording and alerting rules;
* configuration parser was moved to separate package and now performs
more strict validation;
* new endpoint for listing all groups and rules in json format was added;
* evaluation interval may be set to every particular group;
* vmalert: uncomment tests
* vmalert: rm outdated TODO
* vmalert: fix typos in README
Before the change we were sending notifications to notifier
if following conditions are met:
* alert is in Fire state
* alert is in Inactive state
We were sending Inactive notifications to resolve alert ASAP.
Unfortunately, we were sending resolves for Pending alerts that become
Inactive, which is wrong.
In this change we delete alert from the active list if
it was Pending and become Inactive. In this way we now
have Inactive alerts only if they were in state Fire before.
See test change for example.
During group's update rules deletion was causing slice
mutations while slice index was assumed to be unchanged.
This caused "slice bounds out of range" errors when multiple
rules were deleted sequentially.
The check for non-nil remoteRead was mistakenly dropped
during refactoring which caused panics when `vmalert`
wasn't configured with `remoteRead` flag.
* feat: add remoteWrite.maxQueueSize to reduce queue full
* rename remote(write|read) flags to remote(Write|Read) for the sake of consistency
Co-authored-by: xiaobeibei <xiaobeibei@bigo.sg>
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.
* app/vmalert: restore alerts state from datasource metrics
Vmalert will restore alerts state for rules that have `rule.For` > 0 from previously written timeseries via `remotewrite.url` flag.
* app/vmalert: mention remotewerite and remoteread configuration in README
* app/vmalert: initial remote-write support for alerts state persistence.
If `remotewrite.url` flag is set, vmalert will send alerts state via remote-write protocol to remote storage. The sending is asynchronous to avoid blocking calls in rules evaluation loop.
* app/vmalert: merge with master
* app/vmalert: write both `instant` and `for` alerts timeseries states in remote storage.
vmalert: Extend web responses for alerts
* populate apiAlert object with additional fields
* return all active alerts, not only firing
* sort list of API alerts for deterministic output
* add helper for available path list
* 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
