From 16c85d0dc5bcae4af0c21269f6a61140fedfd263 Mon Sep 17 00:00:00 2001
From: Xe Iaso <xe@tailscale.com>
Date: Fri, 15 Jul 2022 10:20:54 -0400
Subject: [PATCH] cmd/gitops-pusher: support GitHub Actions error syntax
 (#5060)

GitHub Actions lets you annotate lines in files as errors[1]. This syntax
will only fire on syntax errors. Future improvements can extend this to
properly annotate ACL tests too.

[1]: https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#setting-an-error-message

Signed-off-by: Xe <xe@tailscale.com>
---
 cmd/gitops-pusher/gitops-pusher.go | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/cmd/gitops-pusher/gitops-pusher.go b/cmd/gitops-pusher/gitops-pusher.go
index 0a1427a4b..14efbc363 100644
--- a/cmd/gitops-pusher/gitops-pusher.go
+++ b/cmd/gitops-pusher/gitops-pusher.go
@@ -17,13 +17,15 @@ import (
 	"log"
 	"net/http"
 	"os"
+	"regexp"
 	"strings"
 	"time"
 )
 
 var (
-	policyFname = flag.String("policy-file", "./policy.hujson", "filename for policy file")
-	timeout     = flag.Duration("timeout", 5*time.Minute, "timeout for the entire CI run")
+	policyFname  = flag.String("policy-file", "./policy.hujson", "filename for policy file")
+	timeout      = flag.Duration("timeout", 5*time.Minute, "timeout for the entire CI run")
+	githubSyntax = flag.Bool("github-syntax", true, "use GitHub Action error syntax (https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#setting-an-error-message)")
 )
 
 func main() {
@@ -177,13 +179,15 @@ func testNewACLs(ctx context.Context, tailnet, apiKey, policyFname string) error
 		return err
 	}
 
-	if len(ate.Data) != 0 {
+	if len(ate.Message) != 0 || len(ate.Data) != 0 {
 		return ate
 	}
 
 	return nil
 }
 
+var lineColMessageSplit = regexp.MustCompile(`^line ([0-9]+), column ([0-9]+): (.*)$`)
+
 type ACLTestError struct {
 	Message string               `json:"message"`
 	Data    []ACLTestErrorDetail `json:"data"`
@@ -192,7 +196,17 @@ type ACLTestError struct {
 func (ate ACLTestError) Error() string {
 	var sb strings.Builder
 
-	fmt.Fprintln(&sb, ate.Message)
+	if *githubSyntax && lineColMessageSplit.MatchString(ate.Message) {
+		sp := lineColMessageSplit.FindStringSubmatch(ate.Message)
+
+		line := sp[1]
+		col := sp[2]
+		msg := sp[3]
+
+		fmt.Fprintf(&sb, "::error file=%s,line=%s,col=%s::%s", *policyFname, line, col, msg)
+	} else {
+		fmt.Fprintln(&sb, ate.Message)
+	}
 	fmt.Fprintln(&sb)
 
 	for _, data := range ate.Data {