mark disable_compat_1.9 to deprecate in 1.13, change default to true (#12675)

Co-authored-by: R.B. Boyer <4903+rboyer@users.noreply.github.com>

.changelog/12675.txt

@@ -0,0 +1,3 @@
+```release-note:breaking-change
+telemetry: the disable_compat_1.9 option now defaults to true. 1.9 style `consul.http...` metrics can still be enabled by setting `disable_compat_1.9 = false`. However, we will remove these metrics in 1.13.
+```

agent/agent.go

@@ -698,7 +698,7 @@ func (a *Agent) Start(ctx context.Context) error {
 	// DEPRECATED: Warn users if they're emitting deprecated metrics. Remove this warning and the flagged metrics in a
 	// future release of Consul.
 	if !a.config.Telemetry.DisableCompatOneNine {
-		a.logger.Warn("DEPRECATED Backwards compatibility with pre-1.9 metrics enabled. These metrics will be removed in a future version of Consul. Set `telemetry { disable_compat_1.9 = true }` to disable them.")
+		a.logger.Warn("DEPRECATED Backwards compatibility with pre-1.9 metrics enabled. These metrics will be removed in Consul 1.13. Consider not using this flag and rework instrumentation for 1.10 style http metrics.")
 	}
 
 	if a.tlsConfigurator.Cert() != nil {
@@ -3797,7 +3797,7 @@ func (a *Agent) reloadConfig(autoReload bool) error {
 	// DEPRECATED: Warn users on reload if they're emitting deprecated metrics. Remove this warning and the flagged
 	// metrics in a future release of Consul.
 	if !a.config.Telemetry.DisableCompatOneNine {
-		a.logger.Warn("DEPRECATED Backwards compatibility with pre-1.9 metrics enabled. These metrics will be removed in a future version of Consul. Set `telemetry { disable_compat_1.9 = true }` to disable them.")
+		a.logger.Warn("DEPRECATED Backwards compatibility with pre-1.9 metrics enabled. These metrics will be removed in Consul 1.13. Consider not using this flag and rework instrumentation for 1.10 style http metrics.")
 	}
 
 	return a.reloadConfigInternal(newCfg)

agent/config/builder.go

@@ -910,7 +910,7 @@ func (b *builder) build() (rt RuntimeConfig, err error) {
 			CirconusCheckTags:                  stringVal(c.Telemetry.CirconusCheckTags),
 			CirconusSubmissionInterval:         stringVal(c.Telemetry.CirconusSubmissionInterval),
 			CirconusSubmissionURL:              stringVal(c.Telemetry.CirconusSubmissionURL),
-			DisableCompatOneNine:               boolVal(c.Telemetry.DisableCompatOneNine),
+			DisableCompatOneNine:               boolValWithDefault(c.Telemetry.DisableCompatOneNine, true),
 			DisableHostname:                    boolVal(c.Telemetry.DisableHostname),
 			DogstatsdAddr:                      stringVal(c.Telemetry.DogstatsdAddr),
 			DogstatsdTags:                      c.Telemetry.DogstatsdTags,

agent/http.go

@@ -228,8 +228,7 @@ func (s *HTTPHandlers) handler(enableDebug bool) http.Handler {
 			labels := []metrics.Label{{Name: "method", Value: req.Method}, {Name: "path", Value: path_label}}
 			metrics.MeasureSinceWithLabels([]string{"api", "http"}, start, labels)
 
-			// DEPRECATED Emit pre-1.9 metric as `consul.http...` to maintain backwards compatibility. Enabled by
-			// default. Users may set `telemetry { disable_compat_1.9 = true }`
+			// DEPRECATED Emit pre-1.9 metric as `consul.http...`. This will be removed in 1.13.
 			if !s.agent.config.Telemetry.DisableCompatOneNine {
 				key := append([]string{"http", req.Method}, parts...)
 				metrics.MeasureSince(key, start)

agent/metrics_test.go

@@ -255,6 +255,67 @@ func TestHTTPHandlers_AgentMetrics_ConsulAutopilot_Prometheus(t *testing.T) {
 	})
 }
 
+// TestHTTPHandlers_AgentMetrics_Disable1Dot9MetricsChange adds testing around the 1.9 style metrics
+// https://www.consul.io/docs/agent/options#telemetry-disable_compat_1.9
+func TestHTTPHandlers_AgentMetrics_Disable1Dot9MetricsChange(t *testing.T) {
+	skipIfShortTesting(t)
+	// This test cannot use t.Parallel() since we modify global state, ie the global metrics instance
+
+	// 1.9 style http metrics looked like this:
+	// agent_http_2_http_GET_v1_agent_members{quantile="0.5"} 0.1329520046710968
+	t.Run("check that no consul.http metrics are emitted by default", func(t *testing.T) {
+		hcl := `
+		telemetry = {
+			prometheus_retention_time = "5s"
+			disable_hostname = true
+			metrics_prefix = "agent_http"
+		}
+	`
+
+		a := StartTestAgent(t, TestAgent{HCL: hcl})
+		defer a.Shutdown()
+
+		// we have to use the `a.srv.handler()` to actually trigger the wrapped function
+		uri := fmt.Sprintf("http://%s%s", a.HTTPAddr(), "/v1/agent/members")
+		req, err := http.NewRequest("GET", uri, nil)
+		require.NoError(t, err)
+		resp := httptest.NewRecorder()
+		handler := a.srv.handler(true)
+		handler.ServeHTTP(resp, req)
+
+		respRec := httptest.NewRecorder()
+		recordPromMetrics(t, a, respRec)
+
+		assertMetricNotExists(t, respRec, "agent_http_http_GET_v1_agent_members")
+	})
+
+	t.Run("check that we can still turn on consul.http metrics", func(t *testing.T) {
+		hcl := `
+		telemetry = {
+			prometheus_retention_time = "5s",
+			disable_compat_1.9 = false
+			metrics_prefix = "agent_http_2"
+		}
+		`
+
+		a := StartTestAgent(t, TestAgent{HCL: hcl})
+		defer a.Shutdown()
+
+		uri := fmt.Sprintf("http://%s%s", a.HTTPAddr(), "/v1/agent/members")
+		req, err := http.NewRequest("GET", uri, nil)
+		require.NoError(t, err)
+		resp := httptest.NewRecorder()
+
+		handler := a.srv.handler(true)
+		handler.ServeHTTP(resp, req)
+
+		respRec := httptest.NewRecorder()
+		recordPromMetrics(t, a, respRec)
+
+		assertMetricExists(t, respRec, "agent_http_2_http_GET_v1_agent_members")
+	})
+}
+
 func TestHTTPHandlers_AgentMetrics_TLSCertExpiry_Prometheus(t *testing.T) {
 	skipIfShortTesting(t)
 	// This test cannot use t.Parallel() since we modify global state, ie the global metrics instance

website/content/docs/agent/options.mdx

@@ -2175,7 +2175,7 @@ There are also a number of common configuration options supported by all provide
     geo location or datacenter, dc:sfo). By default, this is left blank and not used.
 
   - `disable_compat_1.9` ((#telemetry-disable_compat_1.9))
-    This allows users to disable metrics deprecated in 1.9 so they are no longer emitted, saving on performance and storage in large deployments. Defaults to false.
+    This allows users to disable metrics deprecated in 1.9 so they are no longer emitted, improving performance and reducing storage in large deployments. As of 1.12 this defaults to `true` and will be removed, along with 1.9 style http metrics in 1.13.
 
   - `disable_hostname` ((#telemetry-disable_hostname))
     This controls whether or not to prepend runtime telemetry with the machine's

website/content/docs/upgrading/upgrade-specific.mdx

@@ -14,12 +14,24 @@ provided for their upgrades as a result of new features or changed behavior.
 This page is used to document those details separately from the standard
 upgrade flow.
 
+## Consul 1.12.0
+
+### 1.9 Telemetry Compatibility
+
+#### Changing the default behavior for option
+
+The [`disable_compat_19`](/docs/agent/options#telemetry-disable_compat_1.9) telemetry configuration option now defaults
+to `true`. In prior Consul versions (1.10.x through 1.11.x), the config defaulted to `false`. If you require 1.9 style
+`consul.http...` metrics, you may enable them by setting the flag to `false`. However, be advised that these metrics, as
+well as the flag will be removed in upcoming Consul 1.13. We recommend changing your instrumentation to use 1.10 and later
+style `consul.api.http...` metrics and removing the configuration flag from your setup.
+
 ## Consul 1.11.0
 
 ### 1.10 Compatibility <EnterpriseAlert inline />
 Consul Enterprise versions 1.10.0 through 1.10.4 contain a latent bug that
 causes those client or server agents to deregister their own services or health
-checks when some of the servers have been upgraded to 1.11. Before upgrading Consul Enterprise servers to 1.11, all Consul agents should first 
+checks when some of the servers have been upgraded to 1.11. Before upgrading Consul Enterprise servers to 1.11, all Consul agents should first
 be upgraded to 1.10.7 or higher to ensure forward compatibility and prevent
 flapping of catalog registrations.