Provide command for local previews

cmd/tf-preview-gh/main.go

@@ -0,0 +1,260 @@
+package main
+
+import (
+	"bufio"
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"os"
+	"os/exec"
+	"os/signal"
+	"slices"
+	"strings"
+	"syscall"
+	"time"
+
+	"github.com/cenkalti/backoff"
+	"github.com/google/go-github/v57/github"
+	"github.com/hashicorp/go-slug"
+	"golang.ngrok.com/ngrok"
+	"golang.ngrok.com/ngrok/config"
+)
+
+type LocalContent struct {
+	dir string
+}
+
+func (c *LocalContent) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
+	rw.Header().Set("Content-Type", "application/octet-stream")
+
+	_, err := slug.Pack(c.dir, rw, true)
+	if err != nil {
+		fmt.Printf("failed to pack contents: %+v\n", err)
+		return
+	}
+
+	fmt.Println("workspace was downloaded")
+}
+
+func startServer(ctx context.Context) (string, error) {
+	listenerCtx, cancelListener := context.WithCancel(context.Background())
+
+	connected := make(chan struct{})
+	go func() {
+		select {
+		case <-connected:
+		case <-time.After(10 * time.Second):
+			cancelListener()
+		}
+	}()
+
+	listener, err := ngrok.Listen(listenerCtx, config.HTTPEndpoint(), ngrok.WithAuthtokenFromEnv())
+	if err != nil {
+		return "", err
+	}
+	close(connected)
+
+	cwd, err := os.Getwd()
+	if err != nil {
+		listener.Close()
+		return "", err
+	}
+	handler := &LocalContent{
+		dir: cwd,
+	}
+
+	server := &http.Server{
+		Handler: handler,
+	}
+
+	go func() {
+		<-ctx.Done()
+		shutdownCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+		defer cancel()
+		if err := server.Shutdown(shutdownCtx); err != nil {
+			fmt.Printf("failed to shutdown server: %+v\n", err)
+		}
+	}()
+
+	go func() {
+		if err := server.Serve(listener); err != http.ErrServerClosed {
+			fmt.Printf("server failed: %+v\n", err)
+		}
+	}()
+
+	return listener.URL(), nil
+}
+
+type countingReader struct {
+	io.Reader
+	readBytes int
+}
+
+func (c *countingReader) Read(dst []byte) (int, error) {
+	n, err := c.Reader.Read(dst)
+	c.readBytes += n
+	return n, err
+}
+
+var ignoredGroupNames = []string{
+	"Operating System",
+	"Runner Image",
+	"Runner Image Provisioner",
+	"GITHUB_TOKEN Permissions",
+}
+
+func streamLogs(logsURL *url.URL, skip int64) (int64, error) {
+	logs, err := http.Get(logsURL.String())
+	if err != nil {
+		return 0, err
+	}
+	if logs.StatusCode != http.StatusOK {
+		return 0, fmt.Errorf("invalid status for logs: %d", logs.StatusCode)
+	}
+	defer logs.Body.Close()
+
+	if _, err := io.Copy(io.Discard, io.LimitReader(logs.Body, skip)); err != nil {
+		return 0, err
+	}
+
+	r := &countingReader{Reader: logs.Body}
+	scanner := bufio.NewScanner(r)
+	groupDepth := 0
+	for scanner.Scan() {
+		line := scanner.Text()
+		ts, rest, ok := strings.Cut(line, " ")
+		if !ok {
+			rest = ts
+		}
+		if groupName, ok := strings.CutPrefix(rest, "##[group]"); ok {
+			groupDepth++
+			if !slices.Contains(ignoredGroupNames, groupName) {
+				fmt.Printf("\n# %s\n", groupName)
+			}
+		}
+		if groupDepth == 0 {
+			fmt.Println(rest)
+		}
+		if strings.HasPrefix(rest, "##[endgroup]") {
+			groupDepth--
+		}
+	}
+	if err := scanner.Err(); err != nil {
+		return int64(r.readBytes), err
+	}
+
+	return int64(r.readBytes), err
+}
+
+const (
+	owner            = "ffddorf"
+	repo             = "terraform-playground"
+	workflowFilename = "preview.yaml"
+)
+
+func main() {
+	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
+	defer cancel()
+
+	serverURL, err := startServer(ctx)
+	if err != nil {
+		panic(err)
+	}
+
+	// steal token from GH CLI
+	cmd := exec.CommandContext(ctx, "gh", "auth", "token")
+	out, err := cmd.Output()
+	if err != nil {
+		panic(err)
+	}
+
+	token := strings.TrimSpace(string(out))
+	gh := github.NewClient(nil).WithAuthToken(token)
+
+	startedAt := time.Now().UTC()
+
+	// start workflow
+	_, err = gh.Actions.CreateWorkflowDispatchEventByFileName(ctx,
+		owner, repo, workflowFilename,
+		github.CreateWorkflowDispatchEventRequest{
+			Ref: "main",
+			Inputs: map[string]interface{}{
+				"workspace_transfer_url": serverURL,
+			},
+		},
+	)
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Println("Waiting for run to start...")
+
+	// find workflow run
+	var run *github.WorkflowRun
+	err = backoff.Retry(func() error {
+		workflows, _, err := gh.Actions.ListWorkflowRunsByFileName(
+			ctx, owner, repo, workflowFilename,
+			&github.ListWorkflowRunsOptions{
+				Created: fmt.Sprintf(">=%s", startedAt.Format("2006-01-02T15:04")),
+			},
+		)
+		if err != nil {
+			return backoff.Permanent(err)
+		}
+		if len(workflows.WorkflowRuns) == 0 {
+			return fmt.Errorf("no workflow runs found")
+		}
+
+		run = workflows.WorkflowRuns[0]
+		return nil
+	}, backoff.NewExponentialBackOff())
+	if err != nil {
+		panic(err)
+	}
+
+	var jobID int64
+	err = backoff.Retry(func() error {
+		jobs, _, err := gh.Actions.ListWorkflowJobs(ctx,
+			owner, repo, *run.ID,
+			&github.ListWorkflowJobsOptions{},
+		)
+		if err != nil {
+			return backoff.Permanent(err)
+		}
+		if len(jobs.Jobs) == 0 {
+			return fmt.Errorf("no jobs found")
+		}
+
+		jobID = *jobs.Jobs[0].ID
+		return nil
+	}, backoff.NewExponentialBackOff())
+	if err != nil {
+		panic(err)
+	}
+
+	logsURL, _, err := gh.Actions.GetWorkflowJobLogs(ctx, owner, repo, jobID, 2)
+	if err != nil {
+		panic(err)
+	}
+
+	var readBytes int64
+	for {
+		n, err := streamLogs(logsURL, readBytes)
+		if err != nil {
+			panic(err)
+		}
+		readBytes += n
+
+		// check if job is done
+		job, _, err := gh.Actions.GetWorkflowJobByID(ctx, owner, repo, jobID)
+		if err != nil {
+			panic(err)
+		}
+		if job.CompletedAt != nil {
+			fmt.Println("Job complete.")
+			break
+		}
+	}
+}