add healthz API endpoint

cmd/main.go

@@ -72,6 +72,7 @@ func run(cfg *config.Config) {
 	router.Use(APIMiddleware(svrs, short, cfg))
 	router.Use(StaticMiddleware(cfg))
 
+	router.GET(apiBase+"/healthz", handlers.HandleHealthz)
 	router.GET(apiBase+"/config", handlers.HandleConfigWith(version, commit, date))
 	router.POST(apiBase+"/initiate", handlers.HandleInitiate)
 	router.POST(apiBase+"/part", handlers.HandlePart)

pkg/handlers/healthz.go

@@ -0,0 +1,23 @@
+package handlers
+
+import (
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+	"github.com/stv0g/gose/pkg/server"
+)
+
+// HandleConfigWith returns runtime configuration to the frontend
+func HandleHealthz(c *gin.Context) {
+	svrs := c.MustGet("servers").(server.List)
+
+	// TODO: check health status of notifier?
+	// TODO: check health status of shortener?
+	// shortener := c.MustGet("shortener").(*shortener.Shortener)
+
+	for _, svr := range svrs {
+		if !svr.Healthy() {
+			c.AbortWithStatus(http.StatusInternalServerError)
+		}
+	}
+}

pkg/server/server.go

@@ -5,6 +5,7 @@ import (
 	"net/url"
 	"strings"
 
+	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/service/s3"
 	"github.com/stv0g/gose/pkg/config"
 )
@@ -87,3 +88,12 @@ func (s *Server) DetectImplementation() Implementation {
 		}
 	}
 }
+
+func (s *Server) Healthy() bool {
+	_, err := s.S3.ListObjects(&s3.ListObjectsInput{
+		Bucket:  aws.String(s.Config.Bucket),
+		MaxKeys: aws.Int64(0),
+	})
+
+	return err == nil
+}