Backend image rendering as plugin (#11966)

* rendering: headless chrome progress

* renderer: minor change

* grpc: version hell

* updated grpc libs

* wip: minor progess

* rendering: new image rendering plugin is starting to work

* feat: now phantomjs works as well and updated alerting to use new rendering service

* refactor: renamed renderer package and service to rendering to make renderer name less confusing (rendering is internal service that handles the renderer plugin now)

* rendering: now render key is passed and render auth is working in plugin mode

* removed unneeded lines from gitignore

* rendering: now plugin mode supports waiting for all panels to complete rendering

* fix: LastSeenAt fix for render calls, was not set which causes a lot of updates to Last Seen at during rendering, this should fix sqlite db locked issues in seen in previous releases

* change: changed render tz url parameter to use proper timezone name as chrome does not handle UTC offset TZ values

* fix: another update to tz param generation

* renderer: added http mode to renderer service, new ini setting [rendering] server_url

vendor/github.com/prometheus/common/expfmt/decode.go

@@ -164,9 +164,9 @@ func (sd *SampleDecoder) Decode(s *model.Vector) error {
 }
 
 // ExtractSamples builds a slice of samples from the provided metric
-// families. If an error occurs during sample extraction, it continues to
+// families. If an error occurrs during sample extraction, it continues to
 // extract from the remaining metric families. The returned error is the last
-// error that has occured.
+// error that has occurred.
 func ExtractSamples(o *DecodeOptions, fams ...*dto.MetricFamily) (model.Vector, error) {
 	var (
 		all     model.Vector

vendor/github.com/prometheus/common/expfmt/expfmt.go

@@ -26,7 +26,7 @@ const (
 
 	// The Content-Type values for the different wire protocols.
 	FmtUnknown      Format = `<unknown>`
-	FmtText         Format = `text/plain; version=` + TextVersion
+	FmtText         Format = `text/plain; version=` + TextVersion + `; charset=utf-8`
 	FmtProtoDelim   Format = ProtoFmt + ` encoding=delimited`
 	FmtProtoText    Format = ProtoFmt + ` encoding=text`
 	FmtProtoCompact Format = ProtoFmt + ` encoding=compact-text`

vendor/github.com/prometheus/common/expfmt/text_parse.go

@@ -556,8 +556,8 @@ func (p *TextParser) readTokenUntilWhitespace() {
 // byte considered is the byte already read (now in p.currentByte).  The first
 // newline byte encountered is still copied into p.currentByte, but not into
 // p.currentToken. If recognizeEscapeSequence is true, two escape sequences are
-// recognized: '\\' tranlates into '\', and '\n' into a line-feed character. All
-// other escape sequences are invalid and cause an error.
+// recognized: '\\' translates into '\', and '\n' into a line-feed character.
+// All other escape sequences are invalid and cause an error.
 func (p *TextParser) readTokenUntilNewline(recognizeEscapeSequence bool) {
 	p.currentToken.Reset()
 	escaped := false

vendor/github.com/prometheus/common/model/silence.go

@@ -59,8 +59,8 @@ func (m *Matcher) Validate() error {
 	return nil
 }
 
-// Silence defines the representation of a silence definiton
-// in the Prometheus eco-system.
+// Silence defines the representation of a silence definition in the Prometheus
+// eco-system.
 type Silence struct {
 	ID uint64 `json:"id,omitempty"`
 

vendor/github.com/prometheus/common/model/value.go

@@ -100,7 +100,7 @@ func (s *SamplePair) UnmarshalJSON(b []byte) error {
 }
 
 // Equal returns true if this SamplePair and o have equal Values and equal
-// Timestamps. The sematics of Value equality is defined by SampleValue.Equal.
+// Timestamps. The semantics of Value equality is defined by SampleValue.Equal.
 func (s *SamplePair) Equal(o *SamplePair) bool {
 	return s == o || (s.Value.Equal(o.Value) && s.Timestamp.Equal(o.Timestamp))
 }
@@ -117,7 +117,7 @@ type Sample struct {
 }
 
 // Equal compares first the metrics, then the timestamp, then the value. The
-// sematics of value equality is defined by SampleValue.Equal.
+// semantics of value equality is defined by SampleValue.Equal.
 func (s *Sample) Equal(o *Sample) bool {
 	if s == o {
 		return true