Alerts & Notifications

Sentro's alerting system has two parts: channels (where to send notifications) and rules (when to send them). For advanced on-call scenarios, escalation policies let you define ordered notification sequences.

Alert channels

A channel is a destination for notifications. You configure the channel once, then attach it to one or more alert rules.

Supported channels

Channel	Configuration	Plan
Email	List of recipient email addresses.	All plans
Webhook	URL and optional signing secret.	All plans
Slack	Incoming webhook URL.	All plans
Discord	Discord channel webhook URL.	Starter+
Microsoft Teams	Teams incoming webhook URL.	Pro+
Telegram	Bot token and chat ID.	Pro+
Google Chat	Google Chat space webhook URL.	Pro+
Mattermost	Mattermost incoming webhook URL.	Pro+
PagerDuty	Events API v2 integration key.	Max
OpsGenie	OpsGenie API key.	Max

Channel credentials are encrypted at rest (AES-256-GCM) and are never exposed in API responses.

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Setting up a Slack channel

Slack notifications use Incoming Webhooks — no OAuth app install is required.

Step 1 — Create an Incoming Webhook in Slack

1. Go to api.slack.com/apps and click Create New App → From scratch.
2. Give the app a name (e.g. "Sentro Alerts") and select your workspace.
3. In the left sidebar, click Incoming Webhooks, then toggle Activate Incoming Webhooks on.
4. Click Add New Webhook to Workspace, choose the channel to post to (e.g. #alerts), and click Allow.
5. Copy the webhook URL — it looks like https://hooks.slack.com/services/T.../B.../....

Step 2 — Add the channel in Sentro

1. Open Alerts in the dashboard and click Add Channel.
2. Set Type to Slack and give it a name (e.g. "Ops Slack").
3. Paste the webhook URL and click Create Channel.

Step 3 — Attach an alert rule

Create a rule that targets your new Slack channel. Set the trigger (DOWN, UP, etc.), optionally scope it to a specific monitor, and configure consecutive failures and cooldown to your preference.

Sentro posts a color-coded Block Kit message to the channel on each alert, including the monitor name, status, timestamps, duration, and failure cause.

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Setting up Discord

Discord uses the same Incoming Webhooks mechanism as Slack. In Discord, go to Channel Settings → Integrations → Create Webhook, copy the URL, and add a Discord channel in Sentro using that URL. Alerts appear as rich embeds with color-coded status.

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Setting up Microsoft Teams

1. In your Teams channel, click ⋯ → Connectors → Incoming Webhook.
2. Give it a name, optionally upload an icon, and click Create.
3. Copy the webhook URL and add a Teams channel in Sentro.

Alerts appear as MessageCard notifications in the channel.

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Setting up Telegram

1. Create a bot via @BotFather — run /newbot and follow the prompts. Copy the bot token.
2. Add the bot to your group or channel, then get the chat ID (you can use @userinfobot or the Telegram API).
3. Add a Telegram channel in Sentro, entering the bot token and chat ID.

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Setting up PagerDuty

1. In PagerDuty, go to Services → Add Service (or select an existing one) → Integrations → Add an Integration → choose Events API v2.
2. Copy the Integration Key.
3. Add a PagerDuty channel in Sentro with that key.

Sentro automatically triggers a PagerDuty incident on DOWN/DEGRADED and resolves it on UP using the monitor ID as the deduplication key — no duplicate incidents.

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Setting up OpsGenie

1. In OpsGenie, go to Settings → API key management and create a key with Write access.
2. Add an OpsGenie channel in Sentro with the API key.

Sentro creates a P1 alert on DOWN and automatically closes it on UP.

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Alert rules

An alert rule connects a trigger condition to a channel. When the condition is met, a notification is sent through the channel.

Trigger types

Trigger	Fires when
DOWN	A monitor check fails.
UP	A monitor recovers after being down.
DEGRADED	Response time exceeds the monitor's degraded threshold.
SSL_EXPIRING	An SSL certificate is expiring within the configured window.
DOMAIN_EXPIRING	A domain registration is expiring soon.
HEARTBEAT_MISSED	A heartbeat monitor has not received a ping within its expected interval.

Rule configuration

Alert rules decide who is told and when. Whether something counts as an outage at all is decided first, by the monitor's confirmations setting -- so a rule set to fire after one failure fires as soon as the outage is confirmed, not on an isolated failed check.

Setting	Description	Default
Channel	Which alert channel to notify.	Required
Trigger	Which condition fires this rule.	Required
Monitor	Scope the rule to a specific monitor, or leave empty for all monitors in the organization.	All monitors
Consecutive failures	How many checks in a row must have failed before this channel is told. Lets one channel be notified straight away and another only once an outage has proved itself.	1
Cooldown	Minutes to wait between repeat notifications for the same condition.	5 minutes
Enabled	Toggle the rule on or off without deleting it.	Enabled

Common setups

Basic alerting: Create a DOWN rule and a UP rule on the same email channel. You get notified when things break and when they recover.

Escalation: Create a DOWN rule on Slack with consecutive failures set to 1 (fires as soon as the outage is confirmed). Create another DOWN rule on a webhook channel with consecutive failures set to 5 (fires only if the outage is still going several checks later). Each channel is told at most once per incident.

SSL monitoring: Create an SSL_EXPIRING rule with a long cooldown (1440 minutes = once per day) to get a daily reminder as certificate expiry approaches.

Catch-all rule: Leave the monitor field empty to create an organization-wide rule. Every monitor triggers alerts through this channel. Useful for a shared ops Slack channel.

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Alert history

The dashboard shows a log of all dispatched alerts with:

• Status -- Whether the alert was sent successfully, failed, or was skipped (e.g., during cooldown).
• Channel -- Which channel the alert was sent through.
• Timestamp -- When the alert was dispatched.
• Error details -- If a delivery failed, the reason is captured.

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Escalation policies

note

Escalation policies are available on Pro and Max plans.

An escalation policy defines an ordered sequence of notification steps that fire automatically when an incident opens on a monitor that uses the policy.

How it works

Step	Behavior
Step 0	Fires immediately when the incident is created.
Step 1, 2, …	Fires after the configured delay (minutes) if the incident is still open.
Resolution	All pending steps are cancelled when the incident resolves.

Each step can target multiple channels. For example:

• Step 0 (0 min): Slack #incidents
• Step 1 (5 min): Email to on-call
• Step 2 (15 min): PagerDuty

Creating a policy

1. Go to Settings → Escalation Policies and click New Policy.
2. Give the policy a name (e.g. "Production On-Call").
3. Add steps. For each step, set the delay (Step 0 is always 0 minutes) and pick the channels to notify.
4. Save the policy.

Linking a policy to a monitor

Open the monitor's settings and select the escalation policy from the Escalation Policy dropdown. When the policy is active, alert rules attached to the monitor are bypassed in favour of the policy sequence.

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Circuit breaker

Sentro uses a circuit breaker pattern for alert delivery. If a channel fails 5 times in a row, it is temporarily disabled (circuit open) for 60 seconds. After the cooldown, a single test delivery is attempted (half-open). If it succeeds, the circuit closes and normal delivery resumes. This prevents a broken channel from slowing down alerts to other channels.