---
checkId: check.integration.slack
plugin: stellaops.doctor.integration
severity: info
tags: [notification, slack, webhook]
---
# Slack Webhook

## What It Checks
Reads the Slack webhook URL from `Slack:WebhookUrl` or `Notify:Slack:WebhookUrl`. First validates the URL format: **warns** if the URL does not start with `https://hooks.slack.com/`. Then tests host reachability by sending an HTTP GET to the base URL (`https://hooks.slack.com`). The check **passes** if the Slack host is reachable, **warns** if the host is unreachable or if the URL format is suspicious. Does not send an actual webhook payload to avoid generating noise in the Slack channel.

## Why It Matters
Slack notifications keep operators informed about deployment status, policy violations, security findings, and approval requests in real time. A misconfigured or unreachable Slack webhook means critical alerts go undelivered, potentially delaying incident response, approval workflows, or security remediation.

## Common Causes
- Network connectivity issues between Stella Ops and Slack
- Firewall blocking outbound HTTPS to `hooks.slack.com`
- Proxy misconfiguration preventing external HTTPS
- Webhook URL is malformed or points to the wrong service
- Slack webhook URL has been regenerated (old URL invalidated)

## How to Fix

### Docker Compose
```bash
# Check Slack webhook configuration
grep 'SLACK__WEBHOOKURL\|NOTIFY__SLACK' .env

# Test connectivity to Slack
docker compose exec gateway curl -sv https://hooks.slack.com/ -o /dev/null

# Update webhook URL
echo 'Slack__WebhookUrl=https://hooks.slack.com/services/T.../B.../xxx' >> .env
docker compose restart platform

# If behind a proxy
echo 'HTTP_PROXY=http://proxy:8080' >> .env
echo 'HTTPS_PROXY=http://proxy:8080' >> .env
docker compose restart platform
```

### Bare Metal / systemd
```bash
# Verify configuration
cat /etc/stellaops/appsettings.Production.json | jq '.Slack'

# Test connectivity
curl -sv https://hooks.slack.com/ -o /dev/null

# Update webhook URL
sudo nano /etc/stellaops/appsettings.Production.json
sudo systemctl restart stellaops-platform
```

### Kubernetes / Helm
```yaml
# values.yaml
slack:
  webhookUrl: https://hooks.slack.com/services/T.../B.../xxx
  # or use an existing secret
  existingSecret: stellaops-slack-webhook
```
```bash
helm upgrade stellaops ./chart -f values.yaml
```

## Verification
```
stella doctor run --check check.integration.slack
```

## Related Checks
- `check.integration.teams` -- Microsoft Teams webhook (alternative notification channel)
- `check.integration.webhooks` -- general webhook health monitoring