Merge pull request #8 from systemli/update-readme

Readme: Document how to create X-Signature header

Author: doobry-systemli

README.md

@@ -1,3 +1,19 @@
 # userli-webhook-listener
 
 [![Integration](https://github.com/systemli/userli-webhook-listener/actions/workflows/integration.yml/badge.svg)](https://github.com/systemli/userli-webhook-listener/actions/workflows/integration.yml) [![Quality](https://github.com/systemli/userli-webhook-listener/actions/workflows/quality.yml/badge.svg)](https://github.com/systemli/userli-webhook-listener/actions/workflows/quality.yml) [![Quality Gate Status](https://sonarcloud.io/api/project_badges/measure?project=systemli_userli-webhook-listener&metric=alert_status)](https://sonarcloud.io/summary/new_code?id=systemli_userli-webhook-listener) [![Coverage](https://sonarcloud.io/api/project_badges/measure?project=systemli_userli-webhook-listener&metric=coverage)](https://sonarcloud.io/summary/new_code?id=systemli_userli-webhook-listener) [![Maintainability Rating](https://sonarcloud.io/api/project_badges/measure?project=systemli_userli-webhook-listener&metric=sqale_rating)](https://sonarcloud.io/summary/new_code?id=systemli_userli-webhook-listener)
+
+## Debugging
+
+Cheat sheet for sending requests with X-Signature header:
+
+```shell
+WEBHOOK_LISTENER_URL="https://example.org"
+SECRET="secret"
+PAYLOAD='{"type":"user.deleted","timestamp":"2025-01-01T00:00:00.000000Z","data":{"email":"user@example.org"}}'
+SIGNATURE=$(printf '%s' "$PAYLOAD" | openssl dgst -sha256 -hmac "$SECRET" | sed 's/^.* //')
+
+curl -i "$WEBHOOK_URL 
+	-H "Content-Type: application/json" 
+	-H "X-Signature: $SIGNATURE" 
+	-d "$PAYLOAD"
+```