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frontend: refactor metrics #1413

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merged 1 commit into from
Feb 27, 2025
Merged

frontend: refactor metrics #1413

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5 changes: 1 addition & 4 deletions frontend/cmd/cmd.go
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Original file line number Diff line number Diff line change
Expand Up @@ -109,9 +109,6 @@ func (opts *FrontendOpts) Run() error {
logger := util.DefaultLogger()
logger.Info(fmt.Sprintf("%s (%s) started", frontend.ProgramName, util.Version()))

// Initialize the Prometheus emitter.
prometheusEmitter := frontend.NewPrometheusEmitter(prometheus.DefaultRegisterer)

// Initialize the global OpenTelemetry tracer.
otelShutdown, err := frontend.ConfigureOpenTelemetryTracer(ctx, logger, semconv.CloudRegion(opts.location))
if err != nil {
Expand Down Expand Up @@ -179,7 +176,7 @@ func (opts *FrontendOpts) Run() error {
}
logger.Info(fmt.Sprintf("Application running in %s", opts.location))

f := frontend.NewFrontend(logger, listener, metricsListener, prometheusEmitter, dbClient, opts.location, &csClient)
f := frontend.NewFrontend(logger, listener, metricsListener, prometheus.DefaultRegisterer, dbClient, opts.location, &csClient)

stop := make(chan struct{})
signalChannel := make(chan os.Signal, 1)
Expand Down
3 changes: 1 addition & 2 deletions frontend/go.mod
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Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,6 @@ require (
go.opentelemetry.io/otel/sdk v1.34.0
go.opentelemetry.io/otel/trace v1.34.0
go.uber.org/mock v0.5.0
golang.org/x/exp v0.0.0-20241009180824-f66d83c29e7c
golang.org/x/sync v0.11.0
)

Expand Down Expand Up @@ -86,7 +85,7 @@ require (
github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
github.com/openshift/api v0.0.0-20240429104249-ac9356ba1784
github.com/pkg/browser v0.0.0-20240102092130-5ac0b6a4141c // indirect
github.com/prometheus/client_model v0.6.1 // indirect
github.com/prometheus/client_model v0.6.1
github.com/prometheus/common v0.62.0 // indirect
github.com/prometheus/procfs v0.15.1 // indirect
github.com/skratchdot/open-golang v0.0.0-20200116055534-eef842397966 // indirect
Expand Down
2 changes: 0 additions & 2 deletions frontend/go.sum
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Original file line number Diff line number Diff line change
Expand Up @@ -228,8 +228,6 @@ golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8U
golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
golang.org/x/crypto v0.33.0 h1:IOBPskki6Lysi0lo9qQvbxiQ+FvsCC/YWOecCHAixus=
golang.org/x/crypto v0.33.0/go.mod h1:bVdXmD7IV/4GdElGPozy6U7lWdRXA4qyRVGJV57uQ5M=
golang.org/x/exp v0.0.0-20241009180824-f66d83c29e7c h1:7dEasQXItcW1xKJ2+gg5VOiBnqWrJc+rq0DPKyvvdbY=
golang.org/x/exp v0.0.0-20241009180824-f66d83c29e7c/go.mod h1:NQtJDoLvd6faHhE7m4T/1IY708gDefGGjR/iUW8yQQ8=
golang.org/x/mod v0.2.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
Expand Down
7 changes: 7 additions & 0 deletions frontend/pkg/frontend/const.go
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Original file line number Diff line number Diff line change
Expand Up @@ -18,4 +18,11 @@ const (
PathSegmentResourceGroupName = "resourcegroupname"
PathSegmentResourceName = "resourcename"
PathSegmentSubscriptionID = "subscriptionid"

healthGaugeName = "frontend_health"
requestCounterName = "frontend_http_requests_total"
requestDurationName = "frontend_http_requests_duration_seconds"

noMatchRouteLabel = "<no match>"
unknownVersionLabel = "<unknown>"
)
46 changes: 45 additions & 1 deletion frontend/pkg/frontend/context.go
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@mbarnes mbarnes Feb 27, 2025 •
edited
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Appreciate the refactoring of the context API. I won't ask for it this time but in the future it would be good to split refactoring into one or more focused commits for easier review. There's a lot packed into this one commit.

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Right, I got a bit too enthusiastic here.

Original file line number Diff line number Diff line change
Expand Up @@ -15,17 +15,43 @@ import (

type ContextError struct {
got any
key contextKey
}

func (c *ContextError) Error() string {
return fmt.Sprintf(
"error retrieving value from context, value obtained was '%v' and type obtained was '%T'",
"error retrieving value for key %q from context, value obtained was '%v' and type obtained was '%T'",
c.key,
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Nice.

c.got,
c.got)
}

type contextKey int

func (c contextKey) String() string {
switch c {
case contextKeyOriginalPath:
return "originalPath"
case contextKeyBody:
return "body"
case contextKeyLogger:
return "logger"
case contextKeyVersion:
return "version"
case contextKeyDBClient:
return "dbClient"
case contextKeyResourceID:
return "resourceID"
case contextKeyCorrelationData:
return "correlationData"
case contextKeySystemData:
return "systemData"
case contextKeyPattern:
return "pattern"
}
return "<unknown>"
}

const (
// Keys for request-scoped data in http.Request contexts
contextKeyOriginalPath contextKey = iota
Expand All @@ -36,6 +62,7 @@ const (
contextKeyResourceID
contextKeyCorrelationData
contextKeySystemData
contextKeyPattern
)

func ContextWithOriginalPath(ctx context.Context, originalPath string) context.Context {
Expand All @@ -47,6 +74,7 @@ func OriginalPathFromContext(ctx context.Context) (string, error) {
if !ok {
err := &ContextError{
got: originalPath,
key: contextKeyOriginalPath,
}
return originalPath, err
}
Expand All @@ -62,6 +90,7 @@ func BodyFromContext(ctx context.Context) ([]byte, error) {
if !ok {
err := &ContextError{
got: body,
key: contextKeyBody,
}
return body, err
}
Expand All @@ -77,6 +106,7 @@ func LoggerFromContext(ctx context.Context) *slog.Logger {
if !ok {
err := &ContextError{
got: logger,
key: contextKeyLogger,
}
// Return the default logger as a fail-safe, but log
// the failure to obtain the logger from the context.
Expand All @@ -95,6 +125,7 @@ func VersionFromContext(ctx context.Context) (api.Version, error) {
if !ok {
err := &ContextError{
got: version,
key: contextKeyVersion,
}
return version, err
}
Expand All @@ -110,6 +141,7 @@ func DBClientFromContext(ctx context.Context) (database.DBClient, error) {
if !ok {
err := &ContextError{
got: dbClient,
key: contextKeyDBClient,
}
return dbClient, err
}
Expand All @@ -125,6 +157,7 @@ func ResourceIDFromContext(ctx context.Context) (*azcorearm.ResourceID, error) {
if !ok {
err := &ContextError{
got: resourceID,
key: contextKeyResourceID,
}
return resourceID, err
}
Expand All @@ -140,6 +173,7 @@ func CorrelationDataFromContext(ctx context.Context) (*arm.CorrelationData, erro
if !ok {
err := &ContextError{
got: correlationData,
key: contextKeyCorrelationData,
}
return correlationData, err
}
Expand All @@ -155,8 +189,18 @@ func SystemDataFromContext(ctx context.Context) (*arm.SystemData, error) {
if !ok {
err := &ContextError{
got: systemData,
key: contextKeySystemData,
}
return systemData, err
}
return systemData, nil
}

func ContextWithPattern(ctx context.Context, pattern *string) context.Context {
return context.WithValue(ctx, contextKeyPattern, pattern)
}

func PatternFromContext(ctx context.Context) *string {
pattern, _ := ctx.Value(contextKeyPattern).(*string)
return pattern
}
46 changes: 28 additions & 18 deletions frontend/pkg/frontend/frontend.go
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@ import (
azcorearm "github.com/Azure/azure-sdk-for-go/sdk/azcore/arm"
arohcpv1alpha1 "github.com/openshift-online/ocm-sdk-go/arohcp/v1alpha1"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promauto"
"golang.org/x/sync/errgroup"

"github.com/Azure/ARO-HCP/frontend/pkg/metrics"
Expand All @@ -39,16 +40,24 @@ type Frontend struct {
dbClient database.DBClient
ready atomic.Value
done chan struct{}
metrics Emitter
location string
collector *metrics.SubscriptionCollector
healthGauge prometheus.Gauge
}

func NewFrontend(logger *slog.Logger, listener net.Listener, metricsListener net.Listener, emitter Emitter, dbClient database.DBClient, location string, csClient ocm.ClusterServiceClientSpec) *Frontend {
func NewFrontend(
logger *slog.Logger,
listener net.Listener,
metricsListener net.Listener,
reg prometheus.Registerer,
dbClient database.DBClient,
location string,
csClient ocm.ClusterServiceClientSpec,
) *Frontend {
f := &Frontend{
clusterServiceClient: csClient,
listener: listener,
metricsListener: metricsListener,
metrics: emitter,
server: http.Server{
ErrorLog: slog.NewLogLogger(logger.Handler(), slog.LevelError),
BaseContext: func(net.Listener) context.Context {
Expand All @@ -64,12 +73,19 @@ func NewFrontend(logger *slog.Logger, listener net.Listener, metricsListener net
return ContextWithLogger(context.Background(), logger)
},
},
dbClient: dbClient,
done: make(chan struct{}),
location: strings.ToLower(location),
dbClient: dbClient,
done: make(chan struct{}),
location: strings.ToLower(location),
collector: metrics.NewSubscriptionCollector(reg, dbClient, location),
healthGauge: promauto.With(reg).NewGauge(
prometheus.GaugeOpts{
Name: healthGaugeName,
Help: "Reports the health status of the service (0: not healthy, 1: healthy).",
},
),
}

f.server.Handler = f.routes()
f.server.Handler = f.routes(reg)
f.metricsServer.Handler = f.metricsRoutes()

return f
Expand Down Expand Up @@ -101,8 +117,7 @@ func (f *Frontend) Run(ctx context.Context, stop <-chan struct{}) {
return f.metricsServer.Serve(f.metricsListener)
})
errs.Go(func() error {
collector := metrics.NewSubscriptionCollector(prometheus.DefaultRegisterer, f.dbClient, f.location)
collector.Run(logger, stop)
f.collector.Run(logger, stop)
return nil
})

Expand Down Expand Up @@ -137,19 +152,14 @@ func (f *Frontend) NotFound(writer http.ResponseWriter, request *http.Request) {
}

func (f *Frontend) Healthz(writer http.ResponseWriter, request *http.Request) {
var healthStatus float64

if f.CheckReady(request.Context()) {
writer.WriteHeader(http.StatusOK)
healthStatus = 1.0
} else {
arm.WriteInternalServerError(writer)
healthStatus = 0.0
f.healthGauge.Set(1.0)
return
}

f.metrics.EmitGauge("frontend_health", healthStatus, map[string]string{
"endpoint": "/healthz",
})
arm.WriteInternalServerError(writer)
f.healthGauge.Set(0.0)
}

func (f *Frontend) ArmResourceList(writer http.ResponseWriter, request *http.Request) {
Expand Down
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