Slack Notifications

Slack channels receive severity-icon-prefixed messages via a Slack Incoming Webhook. Setup takes about two minutes — create one webhook URL in Slack, paste it into Reoclo, done.

Prerequisites

• A Slack workspace where you can install apps (or someone who can install one for you)
• The Slack channel you want notifications to post to

Step 1 — Create the Slack Incoming Webhook

1. Open https://api.slack.com/apps and click Create New App → From scratch.
2. Name it (e.g., Reoclo Alerts) and pick your workspace.
3. In the left sidebar, open Incoming Webhooks and toggle Activate Incoming Webhooks to On.
4. Scroll down and click Add New Webhook to Workspace.
5. Pick the destination Slack channel and click Allow.
6. Copy the Webhook URL — it looks like https://hooks.slack.com/services/T00000000/B00000000/XXXXXXXXXXXXXXXXXXXXXXXX.

Caution

Treat the webhook URL like a password. Anyone who has it can post to your Slack channel.

If your workspace blocks app installs, ask an admin to install the app or use a Workflow Builder webhook instead — Reoclo posts the same simple text message either way.

Step 2 — Create the channel in Reoclo

Dashboard

1. Open Settings → Notification Channels.
2. Click Add Channel → Slack.
3. Give it a name (e.g., #deploys).
4. Paste the webhook URL into Webhook URL.
5. Click Send Test — a [TEST] message should land in the Slack channel within a second.
6. Pick which events this channel receives.
7. Save.

CLI

reoclo channels create slack \
  --name "deploys" \
  --secret "https://hooks.slack.com/services/T0.../B0.../XXX..." \
  --events deploy_succeeded,deploy_failed

Or via YAML for repeatability:

kind: slack
name: deploys
config: {}
secret: ${env:SLACK_WEBHOOK_URL}
events:
  deploy_succeeded: true
  deploy_failed: true

SLACK_WEBHOOK_URL="https://hooks.slack.com/services/..." \
  reoclo channels create slack --from-file slack-deploys.yaml

Message format

Each post is a single text line prefixed with a severity icon and label:

:red_circle: *CRITICAL* — Deployment failed
Deployment of MyApp to prod-1 failed: exit code 137 (OOM)

Severity	Icon
critical	:red_circle:
warn	:warning:
info	:information_source:
none	:bell:

Messages use Slack’s mrkdwn formatting, so *bold* renders bold. Reoclo expects an HTTP 200 response with body ok — Slack’s standard webhook reply.

Troubleshooting

Symptom	Cause	Fix
404 invalid_token	URL copied wrong or app was uninstalled	Generate a new Incoming Webhook URL and update the channel secret
403 invalid_channel	Channel was deleted or app was removed from it	Add the app back to the channel, or regenerate the webhook for a different channel
Test passes, real events silent	Event toggles disabled	Open the channel and enable the events you want
Posts going to wrong channel	Webhooks are pinned to one channel at creation	Create a new webhook for the new channel — webhooks can’t be moved

Routing tips

• One webhook per channel. Create separate Reoclo channels for #deploys, #alerts, #oncall rather than firehosing one Slack channel.
• Use event filters as routing. A deploys Reoclo channel with only deploy_* events enabled keeps #deploys focused.
• Slack rate limits. Slack accepts ~1 message/sec per webhook. Reoclo’s retry/backoff handles bursts, but very chatty configurations may drop messages — split across multiple webhooks if you regularly exceed this.

Next Steps

• Add a PagerDuty channel for after-hours paging so Slack stays informational
• Configure Alert Rules to wire monitor thresholds into this channel