feat(loki): Add tenant for loki

What :
This change allows to add a "tenant header" in the configuration file at the
loki.tenant key.

Why :
Loki is able to differentiate logs comming from a specific tenant , but
it is needed to add a header in the configuration :

https://grafana.com/docs/loki/latest/operations/multi-tenancy/

This change does not bring any breaking changes.

Signed-off-by: Julien Godin <julien.godin@camptocamp.com>

config.go

@@ -117,6 +117,7 @@ func getConfig() *types.Configuration {
 	v.SetDefault("Loki.MinimumPriority", "")
 	v.SetDefault("Loki.MutualTLS", false)
 	v.SetDefault("Loki.CheckCert", true)
+	v.SetDefault("Loki.Tenant", "")
 
 	v.SetDefault("AWS.AccessKeyID", "")
 	v.SetDefault("AWS.SecretAccessKey", "")

main.go

@@ -192,6 +192,9 @@ func init() {
 			config.Loki.HostPort = ""
 		} else {
 			outputs.EnabledOutputs = append(outputs.EnabledOutputs, "Loki")
+			if config.Loki.Tenant != "" {
+				lokiClient.AddHeader("X-Scope-OrgID", config.Loki.Tenant)
+			}
 		}
 	}
 

types/types.go

@@ -190,6 +190,7 @@ type lokiOutputConfig struct {
 	MinimumPriority string
 	CheckCert       bool
 	MutualTLS       bool
+	Tenant          string
 }
 
 type natsOutputConfig struct {