chore!: adopt log/slog, drop go-kit/log (prometheus#4089)

* chore!: adopt log/slog, drop go-kit/log

The bulk of this change set was automated by the following script which
is being used to aid in converting the various exporters/projects to use
slog:

https://gist.github.com/tjhop/49f96fb7ebbe55b12deee0b0312d8434

This commit includes several changes:
- bump exporter-tookit to v0.13.1 for log/slog support
- updates golangci-lint deprecated configs
- enables sloglint linter
- removes old go-kit/log linter configs
- introduce some `if logger == nil { $newLogger }` additions to prevent
  nil references
- converts cluster membership config to use a stdlib compatible slog
  adapter, rather than creating a custom io.Writer for use as the
membership `logOutput` config

Signed-off-by: TJ Hoplock <[email protected]>

* chore: address PR feedback

Signed-off-by: TJ Hoplock <[email protected]>

---------

Signed-off-by: TJ Hoplock <[email protected]>

Author: tjhop

.golangci.yml

@@ -1,9 +1,3 @@
-run:
-  skip-files:
-    # Skip autogenerated files.
-    - ^.*\.(pb|y)\.go$
-  timeout: 5m
-
 output:
   sort-results: true
 
@@ -17,6 +11,7 @@ linters:
     - misspell
     - revive
     - testifylint
+    - sloglint
 
 issues:
   max-issues-per-linter: 0
@@ -25,6 +20,10 @@ issues:
     - path: _test.go
       linters:
         - errcheck
+  exclude-files:
+    # Skip autogenerated files.
+    - ^.*\.(pb|y)\.go$
+  timeout: 5m
 
 linters-settings:
   depguard:
@@ -48,8 +47,6 @@ linters-settings:
       - (net/http.ResponseWriter).Write
       # No need to check for errors on server's shutdown.
       - (*net/http.Server).Shutdown
-      # Never check for logger errors.
-      - (github.com/go-kit/log.Logger).Log
       # Never check for rollback errors as Rollback() is called when a previous error was detected.
       - (github.com/prometheus/prometheus/storage.Appender).Rollback
   godot:

api/api.go

@@ -16,13 +16,14 @@ package api
 import (
 	"errors"
 	"fmt"
+	"log/slog"
 	"net/http"
 	"runtime"
 	"time"
 
-	"github.com/go-kit/log"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/model"
+	"github.com/prometheus/common/promslog"
 	"github.com/prometheus/common/route"
 
 	apiv2 "github.com/prometheus/alertmanager/api/v2"
@@ -70,7 +71,7 @@ type Options struct {
 	// the concurrency limit.
 	Concurrency int
 	// Logger is used for logging, if nil, no logging will happen.
-	Logger log.Logger
+	Logger *slog.Logger
 	// Registry is used to register Prometheus metrics. If nil, no metrics
 	// registration will happen.
 	Registry prometheus.Registerer
@@ -107,7 +108,7 @@ func New(opts Options) (*API, error) {
 	}
 	l := opts.Logger
 	if l == nil {
-		l = log.NewNopLogger()
+		l = promslog.NewNopLogger()
 	}
 	concurrency := opts.Concurrency
 	if concurrency < 1 {
@@ -124,7 +125,7 @@ func New(opts Options) (*API, error) {
 		opts.GroupMutedFunc,
 		opts.Silences,
 		opts.Peer,
-		log.With(l, "version", "v2"),
+		l.With("version", "v2"),
 		opts.Registry,
 	)
 	if err != nil {
@@ -153,7 +154,7 @@ func New(opts Options) (*API, error) {
 	}
 
 	return &API{
-		deprecationRouter:        NewV1DeprecationRouter(log.With(l, "version", "v1")),
+		deprecationRouter:        NewV1DeprecationRouter(l.With("version", "v1")),
 		v2:                       v2,
 		requestsInFlight:         requestsInFlight,
 		concurrencyLimitExceeded: concurrencyLimitExceeded,

api/v1_deprecation_router.go

@@ -13,20 +13,19 @@ package api
 
 import (
 	"encoding/json"
+	"log/slog"
 	"net/http"
 
-	"github.com/go-kit/log"
-	"github.com/go-kit/log/level"
 	"github.com/prometheus/common/route"
 )
 
 // V1DeprecationRouter is the router to signal v1 users that the API v1 is now removed.
 type V1DeprecationRouter struct {
-	logger log.Logger
+	logger *slog.Logger
 }
 
 // NewV1DeprecationRouter returns a new V1DeprecationRouter.
-func NewV1DeprecationRouter(l log.Logger) *V1DeprecationRouter {
+func NewV1DeprecationRouter(l *slog.Logger) *V1DeprecationRouter {
 	return &V1DeprecationRouter{
 		logger: l,
 	}
@@ -47,7 +46,7 @@ func (dr *V1DeprecationRouter) Register(r *route.Router) {
 }
 
 func (dr *V1DeprecationRouter) deprecationHandler(w http.ResponseWriter, req *http.Request) {
-	level.Warn(dr.logger).Log("msg", "v1 API received a request on a removed endpoint", "path", req.URL.Path, "method", req.Method)
+	dr.logger.Warn("v1 API received a request on a removed endpoint", "path", req.URL.Path, "method", req.Method)
 
 	resp := struct {
 		Status string `json:"status"`
@@ -61,6 +60,6 @@ func (dr *V1DeprecationRouter) deprecationHandler(w http.ResponseWriter, req *ht
 	w.WriteHeader(410)
 
 	if err := json.NewEncoder(w).Encode(resp); err != nil {
-		level.Error(dr.logger).Log("msg", "failed to write response", "err", err)
+		dr.logger.Error("failed to write response", "err", err)
 	}
 }

api/v2/api.go

@@ -16,14 +16,13 @@ package v2
 import (
 	"errors"
 	"fmt"
+	"log/slog"
 	"net/http"
 	"regexp"
 	"sort"
 	"sync"
 	"time"
 
-	"github.com/go-kit/log"
-	"github.com/go-kit/log/level"
 	"github.com/go-openapi/analysis"
 	"github.com/go-openapi/loads"
 	"github.com/go-openapi/runtime/middleware"
@@ -71,7 +70,7 @@ type API struct {
 	route              *dispatch.Route
 	setAlertStatus     setAlertStatusFn
 
-	logger log.Logger
+	logger *slog.Logger
 	m      *metrics.Alerts
 
 	Handler http.Handler
@@ -92,7 +91,7 @@ func NewAPI(
 	gmf groupMutedFunc,
 	silences *silence.Silences,
 	peer cluster.ClusterPeer,
-	l log.Logger,
+	l *slog.Logger,
 	r prometheus.Registerer,
 ) (*API, error) {
 	api := API{
@@ -154,8 +153,8 @@ func setResponseHeaders(h http.Handler) http.Handler {
 	})
 }
 
-func (api *API) requestLogger(req *http.Request) log.Logger {
-	return log.With(api.logger, "path", req.URL.Path, "method", req.Method)
+func (api *API) requestLogger(req *http.Request) *slog.Logger {
+	return api.logger.With("path", req.URL.Path, "method", req.Method)
 }
 
 // Update sets the API struct members that may change between reloads of alertmanager.
@@ -249,14 +248,14 @@ func (api *API) getAlertsHandler(params alert_ops.GetAlertsParams) middleware.Re
 
 	matchers, err := parseFilter(params.Filter)
 	if err != nil {
-		level.Debug(logger).Log("msg", "Failed to parse matchers", "err", err)
+		logger.Debug("Failed to parse matchers", "err", err)
 		return alertgroup_ops.NewGetAlertGroupsBadRequest().WithPayload(err.Error())
 	}
 
 	if params.Receiver != nil {
 		receiverFilter, err = regexp.Compile("^(?:" + *params.Receiver + ")$")
 		if err != nil {
-			level.Debug(logger).Log("msg", "Failed to compile receiver regex", "err", err)
+			logger.Debug("Failed to compile receiver regex", "err", err)
 			return alert_ops.
 				NewGetAlertsBadRequest().
 				WithPayload(
@@ -301,7 +300,7 @@ func (api *API) getAlertsHandler(params alert_ops.GetAlertsParams) middleware.Re
 	api.mtx.RUnlock()
 
 	if err != nil {
-		level.Error(logger).Log("msg", "Failed to get alerts", "err", err)
+		logger.Error("Failed to get alerts", "err", err)
 		return alert_ops.NewGetAlertsInternalServerError().WithPayload(err.Error())
 	}
 	sort.Slice(res, func(i, j int) bool {
@@ -361,12 +360,12 @@ func (api *API) postAlertsHandler(params alert_ops.PostAlertsParams) middleware.
 		validAlerts = append(validAlerts, a)
 	}
 	if err := api.alerts.Put(validAlerts...); err != nil {
-		level.Error(logger).Log("msg", "Failed to create alerts", "err", err)
+		logger.Error("Failed to create alerts", "err", err)
 		return alert_ops.NewPostAlertsInternalServerError().WithPayload(err.Error())
 	}
 
 	if validationErrs.Len() > 0 {
-		level.Error(logger).Log("msg", "Failed to validate alerts", "err", validationErrs.Error())
+		logger.Error("Failed to validate alerts", "err", validationErrs.Error())
 		return alert_ops.NewPostAlertsBadRequest().WithPayload(validationErrs.Error())
 	}
 
@@ -378,15 +377,15 @@ func (api *API) getAlertGroupsHandler(params alertgroup_ops.GetAlertGroupsParams
 
 	matchers, err := parseFilter(params.Filter)
 	if err != nil {
-		level.Debug(logger).Log("msg", "Failed to parse matchers", "err", err)
+		logger.Debug("Failed to parse matchers", "err", err)
 		return alertgroup_ops.NewGetAlertGroupsBadRequest().WithPayload(err.Error())
 	}
 
 	var receiverFilter *regexp.Regexp
 	if params.Receiver != nil {
 		receiverFilter, err = regexp.Compile("^(?:" + *params.Receiver + ")$")
 		if err != nil {
-			level.Error(logger).Log("msg", "Failed to compile receiver regex", "err", err)
+			logger.Error("Failed to compile receiver regex", "err", err)
 			return alertgroup_ops.
 				NewGetAlertGroupsBadRequest().
 				WithPayload(
@@ -518,13 +517,13 @@ func (api *API) getSilencesHandler(params silence_ops.GetSilencesParams) middlew
 
 	matchers, err := parseFilter(params.Filter)
 	if err != nil {
-		level.Debug(logger).Log("msg", "Failed to parse matchers", "err", err)
+		logger.Debug("Failed to parse matchers", "err", err)
 		return silence_ops.NewGetSilencesBadRequest().WithPayload(err.Error())
 	}
 
 	psils, _, err := api.silences.Query()
 	if err != nil {
-		level.Error(logger).Log("msg", "Failed to get silences", "err", err)
+		logger.Error("Failed to get silences", "err", err)
 		return silence_ops.NewGetSilencesInternalServerError().WithPayload(err.Error())
 	}
 
@@ -535,7 +534,7 @@ func (api *API) getSilencesHandler(params silence_ops.GetSilencesParams) middlew
 		}
 		silence, err := GettableSilenceFromProto(ps)
 		if err != nil {
-			level.Error(logger).Log("msg", "Failed to unmarshal silence from proto", "err", err)
+			logger.Error("Failed to unmarshal silence from proto", "err", err)
 			return silence_ops.NewGetSilencesInternalServerError().WithPayload(err.Error())
 		}
 		sils = append(sils, &silence)
@@ -614,18 +613,18 @@ func (api *API) getSilenceHandler(params silence_ops.GetSilenceParams) middlewar
 
 	sils, _, err := api.silences.Query(silence.QIDs(params.SilenceID.String()))
 	if err != nil {
-		level.Error(logger).Log("msg", "Failed to get silence by id", "err", err, "id", params.SilenceID.String())
+		logger.Error("Failed to get silence by id", "err", err, "id", params.SilenceID.String())
 		return silence_ops.NewGetSilenceInternalServerError().WithPayload(err.Error())
 	}
 
 	if len(sils) == 0 {
-		level.Error(logger).Log("msg", "Failed to find silence", "err", err, "id", params.SilenceID.String())
+		logger.Error("Failed to find silence", "err", err, "id", params.SilenceID.String())
 		return silence_ops.NewGetSilenceNotFound()
 	}
 
 	sil, err := GettableSilenceFromProto(sils[0])
 	if err != nil {
-		level.Error(logger).Log("msg", "Failed to convert unmarshal from proto", "err", err)
+		logger.Error("Failed to convert unmarshal from proto", "err", err)
 		return silence_ops.NewGetSilenceInternalServerError().WithPayload(err.Error())
 	}
 
@@ -637,7 +636,7 @@ func (api *API) deleteSilenceHandler(params silence_ops.DeleteSilenceParams) mid
 
 	sid := params.SilenceID.String()
 	if err := api.silences.Expire(sid); err != nil {
-		level.Error(logger).Log("msg", "Failed to expire silence", "err", err)
+		logger.Error("Failed to expire silence", "err", err)
 		if errors.Is(err, silence.ErrNotFound) {
 			return silence_ops.NewDeleteSilenceNotFound()
 		}
@@ -651,26 +650,26 @@ func (api *API) postSilencesHandler(params silence_ops.PostSilencesParams) middl
 
 	sil, err := PostableSilenceToProto(params.Silence)
 	if err != nil {
-		level.Error(logger).Log("msg", "Failed to marshal silence to proto", "err", err)
+		logger.Error("Failed to marshal silence to proto", "err", err)
 		return silence_ops.NewPostSilencesBadRequest().WithPayload(
 			fmt.Sprintf("failed to convert API silence to internal silence: %v", err.Error()),
 		)
 	}
 
 	if sil.StartsAt.After(sil.EndsAt) || sil.StartsAt.Equal(sil.EndsAt) {
 		msg := "Failed to create silence: start time must be before end time"
-		level.Error(logger).Log("msg", msg, "starts_at", sil.StartsAt, "ends_at", sil.EndsAt)
+		logger.Error(msg, "starts_at", sil.StartsAt, "ends_at", sil.EndsAt)
 		return silence_ops.NewPostSilencesBadRequest().WithPayload(msg)
 	}
 
 	if sil.EndsAt.Before(time.Now()) {
 		msg := "Failed to create silence: end time can't be in the past"
-		level.Error(logger).Log("msg", msg, "ends_at", sil.EndsAt)
+		logger.Error(msg, "ends_at", sil.EndsAt)
 		return silence_ops.NewPostSilencesBadRequest().WithPayload(msg)
 	}
 
 	if err = api.silences.Set(sil); err != nil {
-		level.Error(logger).Log("msg", "Failed to create silence", "err", err)
+		logger.Error("Failed to create silence", "err", err)
 		if errors.Is(err, silence.ErrNotFound) {
 			return silence_ops.NewPostSilencesNotFound().WithPayload(err.Error())
 		}

api/v2/api_test.go

@@ -28,6 +28,7 @@ import (
 	"github.com/go-openapi/runtime/middleware"
 	"github.com/go-openapi/strfmt"
 	"github.com/prometheus/common/model"
+	"github.com/prometheus/common/promslog"
 	"github.com/stretchr/testify/require"
 
 	open_api_models "github.com/prometheus/alertmanager/api/v2/models"
@@ -39,8 +40,6 @@ import (
 	"github.com/prometheus/alertmanager/silence"
 	"github.com/prometheus/alertmanager/silence/silencepb"
 	"github.com/prometheus/alertmanager/types"
-
-	"github.com/go-kit/log"
 )
 
 // If api.peers == nil, Alertmanager cluster feature is disabled. Make sure to
@@ -192,7 +191,7 @@ func TestDeleteSilenceHandler(t *testing.T) {
 		api := API{
 			uptime:   time.Now(),
 			silences: silences,
-			logger:   log.NewNopLogger(),
+			logger:   promslog.NewNopLogger(),
 		}
 
 		r, err := http.NewRequest("DELETE", "/api/v2/silence/${tc.sid}", nil)
@@ -274,7 +273,7 @@ func TestPostSilencesHandler(t *testing.T) {
 				api := API{
 					uptime:   time.Now(),
 					silences: silences,
-					logger:   log.NewNopLogger(),
+					logger:   promslog.NewNopLogger(),
 				}
 
 				sil := createSilence(t, tc.sid, "silenceCreator", tc.start, tc.end)
@@ -293,7 +292,7 @@ func TestPostSilencesHandlerMissingIdCreatesSilence(t *testing.T) {
 	api := API{
 		uptime:   time.Now(),
 		silences: silences,
-		logger:   log.NewNopLogger(),
+		logger:   promslog.NewNopLogger(),
 	}
 
 	// Create a new silence. It should be assigned a random UUID.
@@ -557,7 +556,7 @@ receivers:
 	cfg, _ := config.Load(in)
 	api := API{
 		uptime:             time.Now(),
-		logger:             log.NewNopLogger(),
+		logger:             promslog.NewNopLogger(),
 		alertmanagerConfig: cfg,
 	}