tom-henderson · January 7, 2020 03:18 · Jan 7, 2020
diff --git a/slack.py b/slack.py
@@ -0,0 +1,134 @@
+#!/usr/bin/env python3
+
+import os
+import sys
+import json
+import requests
+import argparse
+import re
+
+SLACK_WEBHOOK_URL = os.environ.get("SLACK_WEBHOOK_URL")
+SLACK_DEFAULT_USER = os.environ.get("SLACK_DEFAULT_USER", "Python")
+SLACK_DEFAULT_ICON = os.environ.get("SLACK_DEFAULT_ICON", "python")
+
+def valid_channel(channel):
+    if channel[0] in ("@", "#"):
+        return channel
+    raise argparse.ArgumentTypeError(f"Invalid channel: {channel} does not begin with # or @.")
+
+def valid_icon(icon):
+    if icon[0] != ":":
+        icon = f":{icon}"
+
+    if icon[-1] != ":":
+        icon = f"{icon}:"
+
+    return icon
+
+def valid_colour(colour):
+    named_colours = [
+        "good",
+        "warning",
+        "danger",
+    ]
+
+    if colour in named_colours or re.match(r"^#([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})$", colour):
+        return colour
+
+    raise argparse.ArgumentTypeError(f"Invalid colour: {colour}")
+
+
+parser = argparse.ArgumentParser(description="Send a slack message.")
+parser.add_argument(
+    '-c', '--channel',
+    required=True,
+    type=valid_channel,
+    help="Channel to post to. Must begin with # or @."
+)
+parser.add_argument(
+    '-u', '--username',
+    default=SLACK_DEFAULT_USER,
+    help="Username to post as."
+)
+parser.add_argument(
+    '-m', '--message',
+    default=None,
+    help="Message to send."
+)
+parser.add_argument(
+    '-i', '--icon_emoji',
+    default=SLACK_DEFAULT_ICON,
+    type=valid_icon,
+    help="Emoji to use as icon."
+)
+parser.add_argument(
+    '--colour',
+    default=None,
+    type=valid_colour,
+    help="Post message as a block with a coloured left border."
+)
+args = parser.parse_args()
+
+
+def post_json(url, payload):
+    req = urllib2.Request(url)
+    req.add_header('Content-Type', 'application/json')
+    response = urllib2.urlopen(req, json.dumps(payload))
+    return response
+
+
+def post_to_slack(channel, username, message, icon_emoji, colour=None):
+    headers = {
+        'Content-Type': 'application/json'
+    }
+
+    if (args.colour):
+        payload = json.dumps({
+            'channel': channel,
+            'username': username,
+            'icon_emoji': icon_emoji,
+            "attachments": [
+                {
+                    "text": message.replace('\\n', '\n'),
+                    "color": args.colour,
+                    "mrkdwn_in": ["text"]
+                }
+            ]
+        })
+    else:
+        payload = json.dumps({
+            'channel': channel,
+            'username': username,
+            'text': message.replace('\\n', '\n'),
+            'icon_emoji': icon_emoji,
+        })
+
+    response = requests.post(
+        SLACK_WEBHOOK_URL,
+        data=payload,
+        headers=headers
+    )
+    return response
+
+
+
+if __name__ == '__main__':
+    if not SLACK_WEBHOOK_URL:
+        print('ERROR: SLACK_WEBHOOK_URL is not defined.')
+        sys.exit(1)
+
+    if not args.message:
+        args.message = "".join(sys.stdin.readlines())
+
+    response = post_to_slack(
+        channel=args.channel,
+        username=args.username,
+        message=args.message,
+        icon_emoji=args.icon_emoji,
+        colour=args.colour
+    )
+
+    if response:
+        sys.exit(0)
+    else:
+        sys.exit(1)