add small cmd to rebuild all docker images

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

cmd/build-docker-img/main.go

@@ -0,0 +1,47 @@
+package main
+
+import (
+	"log"
+
+	"github.com/juanfont/headscale/integration"
+	"github.com/juanfont/headscale/integration/tsic"
+	"github.com/ory/dockertest/v3"
+)
+
+func main() {
+	log.Printf("creating docker pool")
+	pool, err := dockertest.NewPool("")
+	if err != nil {
+		log.Fatalf("could not connect to docker: %s", err)
+	}
+
+	log.Printf("creating docker network")
+	network, err := pool.CreateNetwork("docker-integration-net")
+	if err != nil {
+		log.Fatalf("failed to create or get network: %s", err)
+	}
+
+	for _, version := range integration.TailscaleVersions {
+		log.Printf("creating container image for Tailscale (%s)", version)
+
+		tsClient, err := tsic.New(
+			pool,
+			version,
+			network,
+		)
+		if err != nil {
+			log.Fatalf("failed to create tailscale node: %s", err)
+		}
+
+		err = tsClient.Shutdown()
+		if err != nil {
+			log.Fatalf("failed to shut down container: %s", err)
+		}
+	}
+
+	network.Close()
+	err = pool.RemoveNetwork(network)
+	if err != nil {
+		log.Fatalf("failed to remove network: %s", err)
+	}
+}