chenwei791129 Slack Notify
Send messages to Slack channels via Incoming Webhook with mrkdwn formatting support.
Prerequisites
A Slack Incoming Webhook URL is required. Provide it via either:
- Environment variable (recommended for repeated use):
export SLACK_WEBHOOK_URL="https://hooks.slack.com/services/T.../B.../xxx" --webhook-urlargument (for one-off or per-channel sends):uv run scripts/send_slack.py --webhook-url "https://hooks.slack.com/services/..." --text "hello"
The --webhook-url argument takes priority over the environment variable when both are present.
Usage
Send a simple message:
uv run scripts/send_slack.py --text "Deployment complete :rocket:"
Send with mrkdwn formatting:
uv run scripts/send_slack.py --text "*Build succeeded*\nBranch: \`main\`\nCommit: <https://github.com/org/repo/commit/abc123|abc123>"
Send a multiline message via stdin (useful for longer content):
cat <<'EOF' | uv run scripts/send_slack.py
*Daily Report* :bar_chart:
> Total requests: 12,345
> Error rate: 0.02%
> P99 latency: 120ms
_Generated at 2025-03-22 09:00 UTC_
EOF
Send to a specific webhook (overrides env var):
uv run scripts/send_slack.py --webhook-url "https://hooks.slack.com/services/T.../B.../xxx" --text "Alert!"
Arguments
| Argument | Description |
|---|---|
--text, -t |
Message text in mrkdwn format |
--webhook-url |
Incoming Webhook URL (overrides SLACK_WEBHOOK_URL) |
| (stdin) | If --text is not provided, reads message from stdin |
mrkdwn Quick Reference
Slack uses its own markup syntax called mrkdwn (not standard Markdown). Key differences from Markdown:
| Syntax | Renders as |
|---|---|
*bold* |
bold |
_italic_ |
italic |
~strikethrough~ |
|
`inline code` |
inline code |
```code block``` |
code block |
> quote |
blockquote |
\n |
newline (in --text arg) |
<URL|display text> |
hyperlink |
<@U012ABC> |
mention user |
<!channel> |
@channel |
<!here> |
@here |
:emoji_name: |
emoji |
Important rules:
- Slack mrkdwn is NOT standard Markdown.
**bold**will not work — use*bold*instead. - Formatting markers (
*,_,~,`) MUST have a whitespace or newline before the opening marker. They will NOT render after punctuation (especially CJK punctuation like：,，,。). For example:狀態： *running*— works (space before*)狀態：*running*— broken (no space before*)*running*at line start — works
Workflow
When using this skill to send notifications:
- Compose the message content using mrkdwn syntax
- Choose the delivery method:
--textfor single-line or short messages- stdin pipe for multiline or template-based messages
- Run the script via
uv run - Verify the output is
ok
Exit Codes
| Code | Meaning |
|---|---|
| 0 | Message sent successfully |
| 1 | Error (missing webhook URL, missing message, or Slack API error) |
Troubleshooting
| Error | Solution |
|---|---|
| "no webhook URL provided" | Set SLACK_WEBHOOK_URL env var or pass --webhook-url |
| "no message provided" | Pass --text or pipe content via stdin |
| Slack returned non-200 | Check webhook URL is valid and not revoked |
| "channel_not_found" | The webhook's associated channel was deleted |
| "invalid_payload" | Check message formatting — mrkdwn syntax may be malformed |