Tracing configuration json marshal/unmarshal

tracing/config/tracing.go

@@ -17,6 +17,7 @@ limitations under the License.
 package config
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"reflect"
@@ -139,3 +140,43 @@ func NewTracingConfigFromMap(cfgMap map[string]string) (*Config, error) {
 func NewTracingConfigFromConfigMap(config *corev1.ConfigMap) (*Config, error) {
 	return NewTracingConfigFromMap(config.Data)
 }
+
+// JsonToTracingConfig converts a json string of a Config.
+// Returns a non-nil Config always and an eventual error.
+func JsonToTracingConfig(jsonCfg string) (*Config, error) {
+	if jsonCfg == "" {
+		return defaultConfig(), errors.New("empty json tracing config")
+	}
+
+	var configMap map[string]string
+	if err := json.Unmarshal([]byte(jsonCfg), &configMap); err != nil {
+		return defaultConfig(), err
+	}
+
+	cfg, err := NewTracingConfigFromMap(configMap)
+	if err != nil {
+		return defaultConfig(), nil
+	}
+	return cfg, nil
+}
+
+// TracingConfigToJson converts a Config to a json string.
+func TracingConfigToJson(cfg *Config) (string, error) {
+	if cfg == nil {
+		return "", nil
+	}
+
+	out := make(map[string]string, 5)
+	out[backendKey] = string(cfg.Backend)
+	if cfg.ZipkinEndpoint != "" {
+		out[zipkinEndpointKey] = cfg.ZipkinEndpoint
+	}
+	if cfg.StackdriverProjectID != "" {
+		out[stackdriverProjectIDKey] = cfg.StackdriverProjectID
+	}
+	out[debugKey] = fmt.Sprint(cfg.Debug)
+	out[sampleRateKey] = fmt.Sprint(cfg.SampleRate)
+
+	jsonCfg, err := json.Marshal(out)
+	return string(jsonCfg), err
+}

tracing/config/tracing_test.go

@@ -137,6 +137,102 @@ func TestNewConfigSuccess(t *testing.T) {
 	}
 }
 
+func TestNewConfigJson(t *testing.T) {
+	tt := []struct {
+		name   string
+		input  map[string]string
+		output *Config
+	}{{
+		name:   "Empty map",
+		input:  map[string]string{},
+		output: defaultConfig(),
+	}, {
+		name: "Everything enabled (legacy)",
+		input: map[string]string{
+			enableKey:         "true",
+			zipkinEndpointKey: "some-endpoint",
+			debugKey:          "true",
+			sampleRateKey:     "0.5",
+		},
+		output: &Config{
+			Backend:        Zipkin,
+			Debug:          true,
+			ZipkinEndpoint: "some-endpoint",
+			SampleRate:     0.5,
+		},
+	}, {
+		name: "Everything enabled (zipkin)",
+		input: map[string]string{
+			backendKey:        "zipkin",
+			zipkinEndpointKey: "some-endpoint",
+			debugKey:          "true",
+			sampleRateKey:     "0.5",
+		},
+		output: &Config{
+			Backend:        Zipkin,
+			Debug:          true,
+			ZipkinEndpoint: "some-endpoint",
+			SampleRate:     0.5,
+		},
+	}, {
+		name: "Everything enabled (stackdriver)",
+		input: map[string]string{
+			backendKey:              "stackdriver",
+			zipkinEndpointKey:       "some-endpoint",
+			stackdriverProjectIDKey: "my-project",
+			debugKey:                "true",
+			sampleRateKey:           "0.5",
+		},
+		output: &Config{
+			Backend:              Stackdriver,
+			Debug:                true,
+			ZipkinEndpoint:       "some-endpoint",
+			StackdriverProjectID: "my-project",
+			SampleRate:           0.5,
+		},
+	}, {
+		name: "Everything enabled (stackdriver, with enabled)",
+		input: map[string]string{
+			enableKey:               "true",
+			backendKey:              "stackdriver",
+			zipkinEndpointKey:       "some-endpoint",
+			stackdriverProjectIDKey: "my-project",
+			debugKey:                "true",
+			sampleRateKey:           "0.5",
+		},
+		output: &Config{
+			Backend:              Stackdriver,
+			Debug:                true,
+			ZipkinEndpoint:       "some-endpoint",
+			StackdriverProjectID: "my-project",
+			SampleRate:           0.5,
+		},
+	}}
+
+	for _, tc := range tt {
+		t.Run(tc.name, func(t *testing.T) {
+			config, err := NewTracingConfigFromMap(tc.input)
+			if err != nil {
+				t.Fatal("Failed to create tracing config:", err)
+			}
+
+			json, err := TracingConfigToJson(config)
+			if err != nil {
+				t.Fatal("Failed to create tracing config:", err)
+			}
+
+			haveConfig, err := JsonToTracingConfig(json)
+			if err != nil {
+				t.Fatal("Failed to create tracing config:", err)
+			}
+
+			if !cmp.Equal(tc.output, haveConfig) {
+				t.Error("Got config from map (-want, +got) =", cmp.Diff(tc.output, haveConfig))
+			}
+		})
+	}
+}
+
 func TestNewConfigFailures(t *testing.T) {
 	tests := []struct {
 		name  string