root: optimise healthchecks (#5337)

* tests: remove redundant healthchecks

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* internal: do healthcheck within proxy instead of wget to use correct port

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* fix docs

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* fix tags

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

---------

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

internal/outpost/ak/healthcheck/cmd.go

@@ -0,0 +1,38 @@
+package healthcheck
+
+import (
+	"fmt"
+	"net/http"
+	"os"
+
+	log "github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
+	"goauthentik.io/internal/config"
+	"goauthentik.io/internal/utils/web"
+)
+
+var Command = &cobra.Command{
+	Use: "healthcheck",
+	Run: func(cmd *cobra.Command, args []string) {
+		config.Get()
+		os.Exit(check())
+	},
+}
+
+func check() int {
+	h := &http.Client{
+		Transport: web.NewUserAgentTransport("goauthentik.io/healthcheck", http.DefaultTransport),
+	}
+	url := fmt.Sprintf("http://%s/outpost.goauthentik.io/ping", config.Get().Listen.Metrics)
+	res, err := h.Head(url)
+	if err != nil {
+		log.WithError(err).Warning("failed to send healthcheck request")
+		return 1
+	}
+	if res.StatusCode >= 400 {
+		log.WithField("status", res.StatusCode).Warning("unhealthy status code")
+		return 1
+	}
+	log.Debug("successfully checked health")
+	return 0
+}