feat: Environment not directly configurable but read from APP_ENV

We use mitchellh/mapstructure to parse the values from the configuration
into the Config struct. Any private field is ignored by mapstructure; in
this way it can be read directly from the ENV.

pkg/tracking/config.go

@@ -2,13 +2,14 @@ package tracking
 
 import (
 	"fmt"
+	"os"
 
 	cbuilder "git.lo/microservices/sdk/go-sdk/internal/pkg/configuration/builder"
 )
 
 // Config stores the configuration for the tracking.
 type Config struct {
-	Environment string `mapstructure:"environment"`
+	environment string
 	Release     string `mapstructure:"release"`
 	SentryDSN   string `mapstructure:"dsn"`
 	ServerName  string `mapstructure:"servername"`
@@ -17,6 +18,7 @@ type Config struct {
 // NewConfig returns a new TrackingConfig instance
 func NewConfig() (*Config, error) {
 	config := &Config{}
+	config.environment = os.Getenv("APP_ENV")
 
 	viperBuilder := cbuilder.New("sentry")
 

pkg/tracking/sentry.go

@@ -115,7 +115,7 @@ func NewSentryHook(config *Config) (*Hook, error) {
 		// The release to be sent with events.
 		Release: config.Release,
 		// The environment to be sent with events.
-		Environment: config.Environment,
+		Environment: config.environment,
 	})
 	if err != nil {
 		return nil, err