prometheus · SuperQ · Nov 7, 2024 · Nov 7, 2024
diff --git a/.golangci.yml b/.golangci.yml
@@ -11,13 +11,25 @@ linters:
     - govet
     - ineffassign
     - misspell
+    - perfsprint
     - revive
     - staticcheck
     - testifylint
     - unused
 linters-settings:
   goimports:
     local-prefixes: github.com/prometheus/common
+  perfsprint:
+    # Optimizes even if it requires an int or uint type cast.
+    int-conversion: true
+    # Optimizes into `err.Error()` even if it is only equivalent for non-nil errors.
+    err-error: true
+    # Optimizes `fmt.Errorf`.
+    errorf: true
+    # Optimizes `fmt.Sprintf` with only one argument.
+    sprintf1: true
+    # Optimizes into strings concatenation.
+    strconcat: false
   revive:
     rules:
       # https://github.com/mgechev/revive/blob/master/RULES_DESCRIPTIONS.md#unused-parameter

diff --git a/config/http_config.go b/config/http_config.go
@@ -357,33 +357,33 @@ func nonZeroCount[T comparable](values ...T) int {
 func (c *HTTPClientConfig) Validate() error {
 	// Backwards compatibility with the bearer_token field.
 	if len(c.BearerToken) > 0 && len(c.BearerTokenFile) > 0 {
-		return fmt.Errorf("at most one of bearer_token & bearer_token_file must be configured")
+		return errors.New("at most one of bearer_token & bearer_token_file must be configured")
 	}
 	if (c.BasicAuth != nil || c.OAuth2 != nil) && (len(c.BearerToken) > 0 || len(c.BearerTokenFile) > 0) {
-		return fmt.Errorf("at most one of basic_auth, oauth2, bearer_token & bearer_token_file must be configured")
+		return errors.New("at most one of basic_auth, oauth2, bearer_token & bearer_token_file must be configured")
 	}
 	if c.BasicAuth != nil && nonZeroCount(string(c.BasicAuth.Username) != "", c.BasicAuth.UsernameFile != "", c.BasicAuth.UsernameRef != "") > 1 {
-		return fmt.Errorf("at most one of basic_auth username, username_file & username_ref must be configured")
+		return errors.New("at most one of basic_auth username, username_file & username_ref must be configured")
 	}
 	if c.BasicAuth != nil && nonZeroCount(string(c.BasicAuth.Password) != "", c.BasicAuth.PasswordFile != "", c.BasicAuth.PasswordRef != "") > 1 {
-		return fmt.Errorf("at most one of basic_auth password, password_file & password_ref must be configured")
+		return errors.New("at most one of basic_auth password, password_file & password_ref must be configured")
 	}
 	if c.Authorization != nil {
 		if len(c.BearerToken) > 0 || len(c.BearerTokenFile) > 0 {
-			return fmt.Errorf("authorization is not compatible with bearer_token & bearer_token_file")
+			return errors.New("authorization is not compatible with bearer_token & bearer_token_file")
 		}
 		if nonZeroCount(string(c.Authorization.Credentials) != "", c.Authorization.CredentialsFile != "", c.Authorization.CredentialsRef != "") > 1 {
-			return fmt.Errorf("at most one of authorization credentials & credentials_file must be configured")
+			return errors.New("at most one of authorization credentials & credentials_file must be configured")
 		}
 		c.Authorization.Type = strings.TrimSpace(c.Authorization.Type)
 		if len(c.Authorization.Type) == 0 {
 			c.Authorization.Type = "Bearer"
 		}
 		if strings.ToLower(c.Authorization.Type) == "basic" {
-			return fmt.Errorf(`authorization type cannot be set to "basic", use "basic_auth" instead`)
+			return errors.New(`authorization type cannot be set to "basic", use "basic_auth" instead`)
 		}
 		if c.BasicAuth != nil || c.OAuth2 != nil {
-			return fmt.Errorf("at most one of basic_auth, oauth2 & authorization must be configured")
+			return errors.New("at most one of basic_auth, oauth2 & authorization must be configured")
 		}
 	} else {
 		if len(c.BearerToken) > 0 {
@@ -399,16 +399,16 @@ func (c *HTTPClientConfig) Validate() error {
 	}
 	if c.OAuth2 != nil {
 		if c.BasicAuth != nil {
-			return fmt.Errorf("at most one of basic_auth, oauth2 & authorization must be configured")
+			return errors.New("at most one of basic_auth, oauth2 & authorization must be configured")
 		}
 		if len(c.OAuth2.ClientID) == 0 {
-			return fmt.Errorf("oauth2 client_id must be configured")
+			return errors.New("oauth2 client_id must be configured")
 		}
 		if len(c.OAuth2.TokenURL) == 0 {
-			return fmt.Errorf("oauth2 token_url must be configured")
+			return errors.New("oauth2 token_url must be configured")
 		}
 		if nonZeroCount(len(c.OAuth2.ClientSecret) > 0, len(c.OAuth2.ClientSecretFile) > 0, len(c.OAuth2.ClientSecretRef) > 0) > 1 {
-			return fmt.Errorf("at most one of oauth2 client_secret, client_secret_file & client_secret_ref must be configured")
+			return errors.New("at most one of oauth2 client_secret, client_secret_file & client_secret_ref must be configured")
 		}
 	}
 	if err := c.ProxyConfig.Validate(); err != nil {
@@ -735,7 +735,7 @@ func (s *FileSecret) Fetch(ctx context.Context) (string, error) {
 }
 
 func (s *FileSecret) Description() string {
-	return fmt.Sprintf("file %s", s.file)
+	return "file " + s.file
 }
 
 func (s *FileSecret) Immutable() bool {
@@ -753,7 +753,7 @@ func (s *refSecret) Fetch(ctx context.Context) (string, error) {
 }
 
 func (s *refSecret) Description() string {
-	return fmt.Sprintf("ref %s", s.ref)
+	return "ref " + s.ref
 }
 
 func (s *refSecret) Immutable() bool {
@@ -1045,7 +1045,7 @@ func NewTLSConfigWithContext(ctx context.Context, cfg *TLSConfig, optFuncs ...TL
 
 	if cfg.MaxVersion != 0 && cfg.MinVersion != 0 {
 		if cfg.MaxVersion < cfg.MinVersion {
-			return nil, fmt.Errorf("tls_config.max_version must be greater than or equal to tls_config.min_version if both are specified")
+			return nil, errors.New("tls_config.max_version must be greater than or equal to tls_config.min_version if both are specified")
 		}
 	}
 
@@ -1144,19 +1144,19 @@ func (c *TLSConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
 // used.
 func (c *TLSConfig) Validate() error {
 	if nonZeroCount(len(c.CA) > 0, len(c.CAFile) > 0, len(c.CARef) > 0) > 1 {
-		return fmt.Errorf("at most one of ca, ca_file & ca_ref must be configured")
+		return errors.New("at most one of ca, ca_file & ca_ref must be configured")
 	}
 	if nonZeroCount(len(c.Cert) > 0, len(c.CertFile) > 0, len(c.CertRef) > 0) > 1 {
-		return fmt.Errorf("at most one of cert, cert_file & cert_ref must be configured")
+		return errors.New("at most one of cert, cert_file & cert_ref must be configured")
 	}
 	if nonZeroCount(len(c.Key) > 0, len(c.KeyFile) > 0, len(c.KeyRef) > 0) > 1 {
-		return fmt.Errorf("at most one of key and key_file must be configured")
+		return errors.New("at most one of key and key_file must be configured")
 	}
 
 	if c.usingClientCert() && !c.usingClientKey() {
-		return fmt.Errorf("exactly one of key or key_file must be configured when a client certificate is configured")
+		return errors.New("exactly one of key or key_file must be configured when a client certificate is configured")
 	} else if c.usingClientKey() && !c.usingClientCert() {
-		return fmt.Errorf("exactly one of cert or cert_file must be configured when a client key is configured")
+		return errors.New("exactly one of cert or cert_file must be configured when a client key is configured")
 	}
 
 	return nil
@@ -1460,16 +1460,16 @@ type ProxyConfig struct {
 // UnmarshalYAML implements the yaml.Unmarshaler interface.
 func (c *ProxyConfig) Validate() error {
 	if len(c.ProxyConnectHeader) > 0 && (!c.ProxyFromEnvironment && (c.ProxyURL.URL == nil || c.ProxyURL.String() == "")) {
-		return fmt.Errorf("if proxy_connect_header is configured, proxy_url or proxy_from_environment must also be configured")
+		return errors.New("if proxy_connect_header is configured, proxy_url or proxy_from_environment must also be configured")
 	}
 	if c.ProxyFromEnvironment && c.ProxyURL.URL != nil && c.ProxyURL.String() != "" {
-		return fmt.Errorf("if proxy_from_environment is configured, proxy_url must not be configured")
+		return errors.New("if proxy_from_environment is configured, proxy_url must not be configured")
 	}
 	if c.ProxyFromEnvironment && c.NoProxy != "" {
-		return fmt.Errorf("if proxy_from_environment is configured, no_proxy must not be configured")
+		return errors.New("if proxy_from_environment is configured, no_proxy must not be configured")
 	}
 	if c.ProxyURL.URL == nil && c.NoProxy != "" {
-		return fmt.Errorf("if no_proxy is configured, proxy_url must also be configured")
+		return errors.New("if no_proxy is configured, proxy_url must also be configured")
 	}
 	return nil
 }

diff --git a/config/http_config_test.go b/config/http_config_test.go
@@ -609,7 +609,7 @@ func TestNewClientFromInvalidConfig(t *testing.T) {
 					InsecureSkipVerify: true,
 				},
 			},
-			errorMsg: fmt.Sprintf("unable to read CA cert: unable to read file %s", MissingCA),
+			errorMsg: "unable to read CA cert: unable to read file " + MissingCA,
 		},
 		{
 			clientConfig: HTTPClientConfig{
@@ -618,7 +618,7 @@ func TestNewClientFromInvalidConfig(t *testing.T) {
 					InsecureSkipVerify: true,
 				},
 			},
-			errorMsg: fmt.Sprintf("unable to use specified CA cert file %s", InvalidCA),
+			errorMsg: "unable to use specified CA cert file " + InvalidCA,
 		},
 	}
 
@@ -864,7 +864,7 @@ func TestTLSConfigInvalidCA(t *testing.T) {
 				ServerName:         "",
 				InsecureSkipVerify: false,
 			},
-			errorMessage: fmt.Sprintf("unable to read CA cert: unable to read file %s", MissingCA),
+			errorMessage: "unable to read CA cert: unable to read file " + MissingCA,
 		},
 		{
 			configTLSConfig: TLSConfig{
@@ -874,7 +874,7 @@ func TestTLSConfigInvalidCA(t *testing.T) {
 				ServerName:         "",
 				InsecureSkipVerify: false,
 			},
-			errorMessage: fmt.Sprintf("unable to read specified client cert: unable to read file %s", MissingCert),
+			errorMessage: "unable to read specified client cert: unable to read file " + MissingCert,
 		},
 		{
 			configTLSConfig: TLSConfig{
@@ -884,7 +884,7 @@ func TestTLSConfigInvalidCA(t *testing.T) {
 				ServerName:         "",
 				InsecureSkipVerify: false,
 			},
-			errorMessage: fmt.Sprintf("unable to read specified client key: unable to read file %s", MissingKey),
+			errorMessage: "unable to read specified client key: unable to read file " + MissingKey,
 		},
 		{
 			configTLSConfig: TLSConfig{
@@ -1715,7 +1715,7 @@ func TestOAuth2UserAgent(t *testing.T) {
 		ClientSecret:   "2",
 		Scopes:         []string{"A", "B"},
 		EndpointParams: map[string]string{"hi": "hello"},
-		TokenURL:       fmt.Sprintf("%s/token", ts.URL),
+		TokenURL:       ts.URL + "/token",
 	}
 
 	rt, err := NewRoundTripperFromConfig(config, "test_oauth2", WithUserAgent("myuseragent"))
@@ -2281,7 +2281,7 @@ func TestProxyConfig_Proxy(t *testing.T) {
 		},
 		{
 			name:             "valid proxy_url and localhost",
-			proxyConfig:      fmt.Sprintf(`proxy_url: %s`, proxyServer.URL),
+			proxyConfig:      "proxy_url: " + proxyServer.URL,
 			expectedProxyURL: proxyServer.URL,
 			targetURL:        "http://localhost/",
 		},
@@ -2294,7 +2294,7 @@ no_proxy: prometheus.io`, proxyServer.URL),
 		},
 		{
 			name:             "valid proxy_url",
-			proxyConfig:      fmt.Sprintf(`proxy_url: %s`, proxyServer.URL),
+			proxyConfig:      "proxy_url: " + proxyServer.URL,
 			expectedProxyURL: proxyServer.URL,
 			targetURL:        "http://prometheus.io/",
 		},

diff --git a/config/tls_config_test.go b/config/tls_config_test.go
@@ -17,6 +17,7 @@ import (
 	"bytes"
 	"crypto/tls"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -159,7 +160,7 @@ func TestTLSVersionMarshalYAML(t *testing.T) {
 		{
 			input:    TLSVersion(999),
 			expected: "",
-			err:      fmt.Errorf("unknown TLS version: 999"),
+			err:      errors.New("unknown TLS version: 999"),
 		},
 	}
 
@@ -199,7 +200,7 @@ func TestTLSVersionMarshalJSON(t *testing.T) {
 		{
 			input:    TLSVersion(999),
 			expected: "",
-			err:      fmt.Errorf("unknown TLS version: 999"),
+			err:      errors.New("unknown TLS version: 999"),
 		},
 	}
 

diff --git a/expfmt/encode.go b/expfmt/encode.go
@@ -68,7 +68,7 @@ func Negotiate(h http.Header) Format {
 		if escapeParam := ac.Params[model.EscapingKey]; escapeParam != "" {
 			switch Format(escapeParam) {
 			case model.AllowUTF8, model.EscapeUnderscores, model.EscapeDots, model.EscapeValues:
-				escapingScheme = Format(fmt.Sprintf("; escaping=%s", escapeParam))
+				escapingScheme = Format("; escaping=" + escapeParam)
 			default:
 				// If the escaping parameter is unknown, ignore it.
 			}
@@ -101,7 +101,7 @@ func NegotiateIncludingOpenMetrics(h http.Header) Format {
 		if escapeParam := ac.Params[model.EscapingKey]; escapeParam != "" {
 			switch Format(escapeParam) {
 			case model.AllowUTF8, model.EscapeUnderscores, model.EscapeDots, model.EscapeValues:
-				escapingScheme = Format(fmt.Sprintf("; escaping=%s", escapeParam))
+				escapingScheme = Format("; escaping=" + escapeParam)
 			default:
 				// If the escaping parameter is unknown, ignore it.
 			}

diff --git a/expfmt/expfmt.go b/expfmt/expfmt.go
@@ -15,7 +15,7 @@
 package expfmt
 
 import (
-	"fmt"
+	"errors"
 	"strings"
 
 	"github.com/prometheus/common/model"
@@ -109,7 +109,7 @@ func NewOpenMetricsFormat(version string) (Format, error) {
 	if version == OpenMetricsVersion_1_0_0 {
 		return FmtOpenMetrics_1_0_0, nil
 	}
-	return FmtUnknown, fmt.Errorf("unknown open metrics version string")
+	return FmtUnknown, errors.New("unknown open metrics version string")
 }
 
 // WithEscapingScheme returns a copy of Format with the specified escaping

diff --git a/expfmt/openmetrics_create.go b/expfmt/openmetrics_create.go
@@ -152,8 +152,8 @@ func MetricFamilyToOpenMetrics(out io.Writer, in *dto.MetricFamily, options ...E
 	if metricType == dto.MetricType_COUNTER && strings.HasSuffix(compliantName, "_total") {
 		compliantName = name[:len(name)-6]
 	}
-	if toOM.withUnit && in.Unit != nil && !strings.HasSuffix(compliantName, fmt.Sprintf("_%s", *in.Unit)) {
-		compliantName = compliantName + fmt.Sprintf("_%s", *in.Unit)
+	if toOM.withUnit && in.Unit != nil && !strings.HasSuffix(compliantName, "_"+*in.Unit) {
+		compliantName = compliantName + "_" + *in.Unit
 	}
 
 	// Comments, first HELP, then TYPE.

diff --git a/expfmt/text_parse.go b/expfmt/text_parse.go
@@ -895,7 +895,7 @@ func histogramMetricName(name string) string {
 
 func parseFloat(s string) (float64, error) {
 	if strings.ContainsAny(s, "pP_") {
-		return 0, fmt.Errorf("unsupported character in float")
+		return 0, errors.New("unsupported character in float")
 	}
 	return strconv.ParseFloat(s, 64)
 }
diff --git a/model/alert.go b/model/alert.go
@@ -14,6 +14,7 @@
 package model
 
 import (
+	"errors"
 	"fmt"
 	"time"
 )
@@ -89,16 +90,16 @@ func (a *Alert) StatusAt(ts time.Time) AlertStatus {
 // Validate checks whether the alert data is inconsistent.
 func (a *Alert) Validate() error {
 	if a.StartsAt.IsZero() {
-		return fmt.Errorf("start time missing")
+		return errors.New("start time missing")
 	}
 	if !a.EndsAt.IsZero() && a.EndsAt.Before(a.StartsAt) {
-		return fmt.Errorf("start time must be before end time")
+		return errors.New("start time must be before end time")
 	}
 	if err := a.Labels.Validate(); err != nil {
 		return fmt.Errorf("invalid label set: %w", err)
 	}
 	if len(a.Labels) == 0 {
-		return fmt.Errorf("at least one label pair required")
+		return errors.New("at least one label pair required")
 	}
 	if err := a.Annotations.Validate(); err != nil {
 		return fmt.Errorf("invalid annotations: %w", err)

diff --git a/model/metric.go b/model/metric.go
@@ -14,6 +14,7 @@
 package model
 
 import (
+	"errors"
 	"fmt"
 	"regexp"
 	"sort"
@@ -443,7 +444,7 @@ func (e EscapingScheme) String() string {
 
 func ToEscapingScheme(s string) (EscapingScheme, error) {
 	if s == "" {
-		return NoEscaping, fmt.Errorf("got empty string instead of escaping scheme")
+		return NoEscaping, errors.New("got empty string instead of escaping scheme")
 	}
 	switch s {
 	case AllowUTF8: