log internal errors only if HUMANLOG_LOG_LEVEL appropriately set

cmd/humanlog/log.go

@@ -0,0 +1,54 @@
+package main
+
+import (
+	"log"
+	"os"
+)
+
+type loglevel int
+
+const (
+	debuglvl loglevel = iota
+	infolvl
+	warnlvl
+	errorlvl
+)
+
+var logLevel = func() loglevel {
+	switch os.Getenv("HUMANLOG_LOG_LEVEL") {
+	case "debug":
+		return debuglvl
+	case "info":
+		return infolvl
+	case "warn":
+		return warnlvl
+	case "error":
+		return errorlvl
+	default:
+		return errorlvl
+	}
+}()
+
+func logdebug(format string, args ...interface{}) {
+	if logLevel <= debuglvl {
+		log.Printf("[debug] "+format, args...)
+	}
+}
+
+func loginfo(format string, args ...interface{}) {
+	if logLevel <= infolvl {
+		log.Printf("[info] "+format, args...)
+	}
+}
+
+func logwarn(format string, args ...interface{}) {
+	if logLevel <= warnlvl {
+		log.Printf("[warn] "+format, args...)
+	}
+}
+
+func logerror(format string, args ...interface{}) {
+	if logLevel <= errorlvl {
+		log.Printf("[error] "+format, args...)
+	}
+}

cmd/humanlog/versions.go

@@ -190,7 +190,7 @@ func checkForUpdate(ctx context.Context, cfg *config.Config, state *state.State)
 		return nil, nil, false, err
 	}
 	if err := updateFromResMeta(state, msg.Meta, &nextSV, &lastCheckAt); err != nil {
-		log.Printf("failed to persist internal state: %v", err)
+		logwarn("failed to persist internal state: %v", err)
 	}
 
 	return msg.NextVersion, msg.NextArtifact, currentSV.LT(nextSV), nil
@@ -206,12 +206,12 @@ func asyncCheckForUpdate(ctx context.Context, req *checkForUpdateReq, cfg *confi
 				return
 			}
 			// TODO: log to diagnostic file?
-			log.Printf("failed to check for update: %v", err)
+			logwarn("failed to check for update: %v", err)
 			return
 		}
 		nexVersion, err := nextVersion.AsSemver()
 		if err != nil {
-			log.Printf("next version is not a valid semver: %v", err)
+			logwarn("next version is not a valid semver: %v", err)
 			return
 		}
 		out <- &checkForUpdateRes{