[Prometheus Remote Write Exporter for Cortex] Add Enhancements and Fixes (#326)

* Add default quantiles, update config tests, and add quantile tests

* Change sendRequest test to use non-empty request and verify the payload

* Refactor createLabelSet to use label.KeyValue instead of strings

* Refactor ConvertToTimeSeries to add the correct labels for histogram and distribution timeseries

* Change createTimeSeries to use specified NumberKind and update conversion functions

* Remove validCheckpointSet test

* Change mock time to milliseconds for conversion tests

* Fix error where results in TestConvertToTimeSeries weren't being compared

* Update convertFromSum, convertFromLastValue tests to use multiple values

* Add tests for quantiles and distributions in utils module

* Update docker-compose and reduce sleep time in main.go for example project

* Fix docker-compose to pass CI test

* Run make precommit

* Update default Config quantiles

* Update tests to match new quantile defaults

* Run make precommit

Author: Eric Lee

exporters/metric/cortex/config.go

@@ -41,6 +41,9 @@ var (
 	// ErrNoBasicAuthPassword occurs when no password or password file was provided for
 	// basic authentication.
 	ErrNoBasicAuthPassword = fmt.Errorf("no password or password file provided for basic authentication")
+
+	// ErrInvalidQuantiles occurs when the supplied quantiles are not between 0 and 1.
+	ErrInvalidQuantiles = fmt.Errorf("cannot have quantiles that are less than 0 or greater than 1")
 )
 
 // Config contains properties the Exporter uses to export metrics data to Cortex.
@@ -86,6 +89,15 @@ func (c *Config) Validate() error {
 		return ErrTwoBearerTokens
 	}
 
+	// Verify that provided quantiles are between 0 and 1.
+	if c.Quantiles != nil {
+		for _, quantile := range c.Quantiles {
+			if quantile < 0 || quantile > 1 {
+				return ErrInvalidQuantiles
+			}
+		}
+	}
+
 	// Add default values for missing properties.
 	if c.Endpoint == "" {
 		c.Endpoint = "/api/prom/push"
@@ -97,6 +109,9 @@ func (c *Config) Validate() error {
 	if c.PushInterval == 0 {
 		c.PushInterval = 10 * time.Second
 	}
+	if c.Quantiles == nil {
+		c.Quantiles = []float64{0.5, 0.9, 0.95, 0.99}
+	}
 
 	return nil
 }

exporters/metric/cortex/config_data_test.go

@@ -26,6 +26,7 @@ var validatedStandardConfig = cortex.Config{
 	Name:          "Config",
 	RemoteTimeout: 30 * time.Second,
 	PushInterval:  10 * time.Second,
+	Quantiles:     []float64{0.5, 0.9, 0.95, 0.99},
 }
 
 // Config struct with default values other than the remote timeout. This is used to verify
@@ -35,6 +36,17 @@ var validatedCustomTimeoutConfig = cortex.Config{
 	Name:          "Config",
 	RemoteTimeout: 10 * time.Second,
 	PushInterval:  10 * time.Second,
+	Quantiles:     []float64{0.5, 0.9, 0.95, 0.99},
+}
+
+// Config struct with default values other than the quantiles. This is used to verify
+// the output of Validate().
+var validatedQuantilesConfig = cortex.Config{
+	Endpoint:      "/api/prom/push",
+	Name:          "Config",
+	RemoteTimeout: 30 * time.Second,
+	PushInterval:  10 * time.Second,
+	Quantiles:     []float64{0, 0.5, 1},
 }
 
 // Example Config struct with a custom remote timeout.
@@ -110,7 +122,7 @@ var exampleTwoAuthConfig = cortex.Config{
 	BearerToken: "bearer_token",
 }
 
-// Example Config struct with no password for basic authentication
+// Example Config struct with no password for basic authentication.
 var exampleNoPasswordConfig = cortex.Config{
 	Endpoint:      "/api/prom/push",
 	Name:          "Config",
@@ -121,7 +133,7 @@ var exampleNoPasswordConfig = cortex.Config{
 	},
 }
 
-// Example Config struct with no password for basic authentication
+// Example Config struct with no password for basic authentication.
 var exampleNoUsernameConfig = cortex.Config{
 	Endpoint:      "/api/prom/push",
 	Name:          "Config",
@@ -131,3 +143,21 @@ var exampleNoUsernameConfig = cortex.Config{
 		"password": "password",
 	},
 }
+
+// Example Config struct with invalid quantiles.
+var exampleInvalidQuantilesConfig = cortex.Config{
+	Endpoint:      "/api/prom/push",
+	Name:          "Config",
+	RemoteTimeout: 30 * time.Second,
+	PushInterval:  10 * time.Second,
+	Quantiles:     []float64{0, 1, 2, 3},
+}
+
+// Example Config struct with valid quantiles.
+var exampleValidQuantilesConfig = cortex.Config{
+	Endpoint:      "/api/prom/push",
+	Name:          "Config",
+	RemoteTimeout: 30 * time.Second,
+	PushInterval:  10 * time.Second,
+	Quantiles:     []float64{0, 0.5, 1},
+}

exporters/metric/cortex/config_test.go

@@ -91,6 +91,18 @@ func TestValidate(t *testing.T) {
 			expectedConfig: nil,
 			expectedError:  cortex.ErrConflictingAuthorization,
 		},
+		{
+			testName:       "Config with Invalid Quantiles",
+			config:         &exampleInvalidQuantilesConfig,
+			expectedConfig: nil,
+			expectedError:  cortex.ErrInvalidQuantiles,
+		},
+		{
+			testName:       "Config with Valid Quantiles",
+			config:         &exampleValidQuantilesConfig,
+			expectedConfig: &validatedQuantilesConfig,
+			expectedError:  nil,
+		},
 	}
 	for _, test := range tests {
 		t.Run(test.testName, func(t *testing.T) {