From 0f7e13222d087d85c1afd67d22d36f544a39801d Mon Sep 17 00:00:00 2001
From: Julien Dessaux
Date: Sat, 28 Sep 2024 09:45:03 +0200
Subject: feat(tfstate): bootstrap an http server that answers /healthz

---
 .gitignore             |  1 +
 cmd/tfstate/healthz.go | 12 +++++++
 cmd/tfstate/main.go    | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++
 cmd/tfstate/routes.go  |  7 ++++
 go.mod                 |  3 ++
 5 files changed, 116 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 cmd/tfstate/healthz.go
 create mode 100644 cmd/tfstate/main.go
 create mode 100644 cmd/tfstate/routes.go
 create mode 100644 go.mod

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..1788154
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+tfstate
diff --git a/cmd/tfstate/healthz.go b/cmd/tfstate/healthz.go
new file mode 100644
index 0000000..20c72c9
--- /dev/null
+++ b/cmd/tfstate/healthz.go
@@ -0,0 +1,12 @@
+package main
+
+import "net/http"
+
+func handleHealthz() http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Cache-Control", "no-store, no-cache")
+		w.Header().Set("Content-Type", "application/json")
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("{}"))
+	})
+}
diff --git a/cmd/tfstate/main.go b/cmd/tfstate/main.go
new file mode 100644
index 0000000..e0b33a5
--- /dev/null
+++ b/cmd/tfstate/main.go
@@ -0,0 +1,93 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"log"
+	"log/slog"
+	"net"
+	"net/http"
+	"os"
+	"os/signal"
+	"sync"
+	"time"
+)
+
+type Config struct {
+	Host string
+	Port string
+}
+
+func run(
+	ctx context.Context,
+	config *Config,
+	args []string,
+	getenv func(string) string,
+	stdin io.Reader,
+	stdout, stderr io.Writer,
+) error {
+	ctx, cancel := signal.NotifyContext(ctx, os.Interrupt)
+	defer cancel()
+
+	mux := http.NewServeMux()
+	addRoutes(
+		mux,
+	)
+	httpServer := &http.Server{
+		Addr:    net.JoinHostPort(config.Host, config.Port),
+		Handler: mux,
+	}
+	go func() {
+		log.Printf("listening on %s\n", httpServer.Addr)
+		if err := httpServer.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+			fmt.Fprintf(os.Stderr, "error listening and serving: %+v\n", err)
+		}
+	}()
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		<-ctx.Done()
+		shutdownCtx := context.Background()
+		shutdownCtx, cancel := context.WithTimeout(shutdownCtx, 10*time.Second)
+		defer cancel()
+		if err := httpServer.Shutdown(shutdownCtx); err != nil {
+			fmt.Fprintf(os.Stderr, "error shutting down http server: %+v\n", err)
+		}
+	}()
+	wg.Wait()
+
+	return nil
+}
+
+func main() {
+	ctx := context.Background()
+
+	var opts *slog.HandlerOptions
+	if os.Getenv("TFSTATE_DEBUG") != "" {
+		opts = &slog.HandlerOptions{
+			AddSource: true,
+			Level:     slog.LevelDebug,
+		}
+	}
+	logger := slog.New(slog.NewJSONHandler(os.Stdout, opts))
+	slog.SetDefault(logger)
+
+	config := Config{
+		Host: "0.0.0.0",
+		Port: "8080",
+	}
+
+	if err := run(
+		ctx,
+		&config,
+		os.Args,
+		os.Getenv,
+		os.Stdin,
+		os.Stdout, os.Stderr,
+	); err != nil {
+		fmt.Fprintf(os.Stderr, "%+v\n", err)
+		os.Exit(1)
+	}
+}
diff --git a/cmd/tfstate/routes.go b/cmd/tfstate/routes.go
new file mode 100644
index 0000000..f583fc7
--- /dev/null
+++ b/cmd/tfstate/routes.go
@@ -0,0 +1,7 @@
+package main
+
+import "net/http"
+
+func addRoutes(mux *http.ServeMux) {
+	mux.Handle("GET /healthz", handleHealthz())
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..0fa79e2
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module git.adyxax.org/adyxax/tfstate
+
+go 1.23.1
-- 
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