render-lab-tasks-slack

Slack messaging for Render Workflows. Version 0.1.1 implements all ten registered tasks and the registration-free webhook adapter. Version 0.1.0 contained only slack.postMessage.

Install from PyPI with Python 3.12+:

pip install render-lab-tasks-slack==0.1.1

from render import TaskContext, Workflows
from render_lab_tasks_slack.tasks import app as slack_app, post_message

app = Workflows.from_workflows(slack_app)


@app.task(name="example.notify")
async def notify(ctx: TaskContext):
    return await ctx.run(post_message, {"text": "Hello from Python"})

Call app.start() from the workflow entry point. .tasks also exports post_message_impl(ctx, input, deps=...) for testing and re-registration under your own task name. Inject SlackDeps with fake SlackPort/SlackWebPort objects.

Contract

Input requires text and supports title, context, markdown, blocks, attachments, channel, and username. Explicit blocks (including an empty list) override generated blocks. Titles, context, and markdown generate Block Kit; double-star markdown bold becomes Slack single-star bold.

Delivery matches the TypeScript task:

1. A channel plus SLACK_BOT_TOKEN uses chat.postMessage and returns {delivered: true, channel, ts}. This route sends text and blocks; legacy attachments and username are webhook-only, matching the TS implementation.
2. Otherwise SLACK_WEBHOOK_URL is used. Its destination is fixed by Slack; the input channel is informational and is not sent in the webhook payload.
3. Without a usable webhook, print the fallback text and return delivered: false. A bot token without a channel does not select the Web API route.

Absent optional result fields are omitted rather than serialized as null.

Environment

Credentials are read at execution time. HTTPX has a 30-second timeout and no automatic retries. Render retries failures up to four times with a 1000 ms base delay and 2x backoff. Slack Web API ok: false responses raise even with HTTP 200. Slack posts are not exactly-once: a retry after an uncertain delivery can duplicate a message. Webhook exceptions omit the credential-bearing URL.

Full Web API surface

open_thread, update_message, await_reaction, await_reply, add_reaction, schedule_message, list_channel_history, get_permalink, and upload_file are available from .tasks with raw *_impl exports. They require SLACK_BOT_TOKEN or an injected SlackDeps.web. Await operations make one read per durable attempt and throw while the requested reaction/reply is absent. The upload port preserves the pinned TS files.upload endpoint; its current vendor availability remains a live-verification backlog item in both repos.

Webhook adapter

render_lab_tasks_slack.webhooks.slack_adapter(on_event, ...) returns a registration-free adapter for render_lab_triggers. The callback receives the verified event and returns {"task": "namespace.task", "args": [event]} or None. The signing credential SLACK_SIGNING_SECRET is read inside verification unless provided explicitly. Importing this module does not register tasks. Signature checks use the raw body; live delivery remains in the testing backlog.