feat: output change detection in GitHub action mode

README.md

@@ -71,6 +71,9 @@ lint   |    no   | `false` | enable built-in linter
 compact|    no   | `false` | compact instead of pretty-printed output
 raw    |    no   | `false` | output raw strings, not JSON texts
 yaml   |    no   | `false` | output YAML instead of JSON
+ref    |    no   |         | reference output URL for change detection
+
+In GitHub action mode, the change can be indicated by comparing the output to a reference output. The reference output URL can be passed in the `ref` action parameter. The `changed` output variable will be `true` or `false` depending on whether the output has changed or not compared to the reference output.
 
 **Example usage**
 

cmd/k6registry/action.go

@@ -0,0 +1,73 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+//nolint:forbidigo
+func emitOutput() error {
+	out := getenv("INPUT_OUT", "")
+	if len(out) == 0 {
+		return nil
+	}
+
+	ref := getenv("INPUT_REF", "")
+	if len(ref) == 0 {
+		return nil
+	}
+
+	ghOutput := getenv("GITHUB_OUTPUT", "")
+	if len(ghOutput) == 0 {
+		return nil
+	}
+
+	file, err := os.Create(filepath.Clean(ghOutput))
+	if err != nil {
+		return err
+	}
+
+	_, err = fmt.Fprintf(file, "changed=%t\n", isChanged(ref, out))
+	if err != nil {
+		return err
+	}
+
+	return file.Close()
+}
+
+//nolint:forbidigo
+func isChanged(refURL string, localFile string) bool {
+	client := &http.Client{Timeout: httpTimeout}
+
+	req, err := http.NewRequestWithContext(context.TODO(), http.MethodGet, refURL, nil)
+	if err != nil {
+		return true
+	}
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return true
+	}
+
+	defer resp.Body.Close() //nolint:errcheck
+
+	refData, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return true
+	}
+
+	localData, err := os.ReadFile(filepath.Clean(localFile))
+	if err != nil {
+		return true
+	}
+
+	return !bytes.Equal(refData, localData)
+}
+
+const httpTimeout = 10 * time.Second

cmd/k6registry/main.go

@@ -34,6 +34,12 @@ func runCmd(cmd *cobra.Command) {
 	if err := cmd.Execute(); err != nil {
 		log.Fatal(formatError(err))
 	}
+
+	if isGitHubAction() {
+		if err := emitOutput(); err != nil {
+			log.Fatal(formatError(err))
+		}
+	}
 }
 
 //nolint:forbidigo

releases/v0.1.6.md

@@ -0,0 +1,5 @@
+k6registry `v0.1.6` is here 🎉!
+
+This is an internal maintenance release.
+
+The only change is that in GitHub action mode, the change can be indicated by comparing the output to a reference output. The reference output URL can be passed in the `ref` action parameter. The output variable `changed` will be `true` or `false` depending on whether the output has changed or not compared to the reference output.