Add ping command to server to allow container healthchecks (#2030)

Fixes: https://github.com/woodpecker-ci/woodpecker/issues/1943

Note: Kubernetes ignores the container `HEALTHCHECK` by default.

---------

Co-authored-by: 6543 <6543@obermui.de>

cmd/server/health.go

@@ -0,0 +1,63 @@
+// Copyright 2023 Woodpecker Authors
+// Copyright 2018 Drone.IO Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"fmt"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/rs/zerolog/log"
+	"github.com/urfave/cli/v2"
+)
+
+const pingTimeout = 1 * time.Second
+
+// handles pinging the endpoint and returns an error if the
+// server is in an unhealthy state.
+func pinger(c *cli.Context) error {
+	scheme := "http"
+	serverAddr := c.String("server-addr")
+	if strings.HasPrefix(serverAddr, ":") {
+		// this seems sufficient according to https://pkg.go.dev/net#Dial
+		serverAddr = "localhost" + serverAddr
+	}
+
+	// if woodpecker do ssl on it's own
+	if c.String("server-cert") != "" || c.Bool("lets-encrypt") {
+		scheme = "https"
+	}
+
+	// create the health url
+	healthURL := fmt.Sprintf("%s://%s/healthz", scheme, serverAddr)
+	log.Trace().Msgf("try to ping with url '%s'", healthURL)
+
+	// ask server if all is healthy
+	client := http.Client{Timeout: pingTimeout}
+	resp, err := client.Get(healthURL)
+	if err != nil {
+		if strings.Contains(err.Error(), "deadline exceeded") {
+			return fmt.Errorf("ping timeout reached after %s", pingTimeout)
+		}
+		return err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("server returned non-200 status code")
+	}
+	return nil
+}

cmd/server/main.go

@@ -31,6 +31,13 @@ func main() {
 	app.Version = version.String()
 	app.Usage = "woodpecker server"
 	app.Action = run
+	app.Commands = []*cli.Command{
+		{
+			Name:   "ping",
+			Usage:  "ping the server",
+			Action: pinger,
+		},
+	}
 	app.Flags = flags
 
 	setupSwaggerStaticConfig()

docker/Dockerfile.server.alpine.multiarch

@@ -11,4 +11,5 @@ EXPOSE 8000 9000 80 443
 
 COPY dist/server/${TARGETOS}/${TARGETARCH}/woodpecker-server /bin/
 
+HEALTHCHECK CMD ["/bin/woodpecker-server", "ping"]
 ENTRYPOINT ["/bin/woodpecker-server"]

docker/Dockerfile.server.multiarch

@@ -14,4 +14,5 @@ COPY --from=certs /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certifica
 # copy server binary
 COPY dist/server/${TARGETOS}/${TARGETARCH}/woodpecker-server /bin/
 
+HEALTHCHECK CMD ["/bin/woodpecker-server", "ping"]
 ENTRYPOINT ["/bin/woodpecker-server"]