worker: add metrics

use prometheus to gather metrics

internal/worker/server.go

@@ -19,6 +19,7 @@ import (
 	"github.com/labstack/echo/v4"
 
 	"github.com/osbuild/osbuild-composer/internal/jobqueue"
+	"github.com/osbuild/osbuild-composer/internal/prometheus"
 	"github.com/osbuild/osbuild-composer/internal/worker/api"
 )
 
@@ -300,6 +301,16 @@ func (s *Server) FinishJob(token uuid.UUID, result json.RawMessage) error {
 		}
 	}
 
+	var jobResult OSBuildJobResult
+	_, _, err = s.JobStatus(jobId, &jobResult)
+	if err != nil {
+		return fmt.Errorf("error finding job status: %v", err)
+	}
+
+	if jobResult.Success {
+		prometheus.ComposeSuccesses.Inc()
+	}
+
 	// Move artifacts from the temporary location to the final job
 	// location. Log any errors, but do not treat them as fatal. The job is
 	// already finished.