Slack webhook support

README.md

 
 LaS can send messages to a ReportBot instance.
 
+### Slack
+
+LaS accepts Slack-style webhooks. There are no configuration options.
+
 ## Contributing
 
 All code is formatted using [Black](https://github.com/ambv/black) with

lineandsinker/services/__init__.py

 from .gitea import Gitea
 from .jenkins import Jenkins
 from .reportbot import ReportBot
+from .slack import Slack
 
 
 def docker_factory():
     )
 
 
+def slack_factory():
+    return Slack()
+
+
 services = {
     "docker": docker_factory(),
     "gitea": gitea_factory(),
     "jenkins": jenkins_factory(),
     "reportbot": reportbot_factory(),
+    "slack": slack_factory(),
 }

lineandsinker/services/slack.py

+import json
+
+from .service import Service
+
+
+class Slack(Service):
+    def __init__(self):
+        super().__init__("slack")
+
+    def accept_hook(self, identifier, request):
+        if request.content_type == "application/json":
+            content = request.json()
+        else:
+            content = json.loads(request.get_data()["payload"])
+
+        yield {"type": f"slack", "source": identifier, "text": content["text"]}

main.py

             services["reportbot"].announce(
                 f"\002[registry]\002 New manifest pushed to {event['host']}/{event['repo']}:{event['tag']} by {event['user']}"
             )
+        elif event["type"] == "slack":
+            services["reportbot"].announce(
+                f"\002[{event['source']}]\002 {event['text']}"
+            )
 
 
 @app.route("/")