dozzle/docs/guide/alerts-and-webhooks.md

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Alerts & Webhooks

Alerts & Webhooks

Dozzle v10 introduces a powerful alerting system that lets you monitor container logs and receive notifications when specific conditions are met. Alerts use customizable expressions to filter containers and log messages, and can send notifications to webhooks, Slack, Discord, ntfy, or Dozzle Cloud.

How It Works

Alerts are configured with two expressions:

1. Container filter — selects which containers to monitor
2. Log filter — defines which log messages trigger the alert

When a log entry matches both filters, Dozzle sends a notification to the configured destination.

Important

Alert and destination configurations are stored in the /data directory. You must mount this directory as a volume to persist your notification settings across container restarts.

::: code-group

docker run -v /var/run/docker.sock:/var/run/docker.sock -v /path/to/data:/data -p 8080:8080 amir20/dozzle:latest

services:
  dozzle:
    image: amir20/dozzle:latest
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - /path/to/data:/data
    ports:
      - 8080:8080

:::

Setting Up a Destination

Before creating alerts, you need to configure at least one notification destination. Navigate to the Notifications page in Dozzle and click Add Destination.

Webhook

Webhooks send an HTTP POST request to a URL of your choice. Dozzle includes built-in payload templates for popular services:

• Slack — formatted with blocks and markdown
• Discord — formatted for Discord webhook API
• ntfy — formatted for ntfy.sh push notifications
• Custom — generic JSON payload you can customize

You can also write your own payload template using Go's text/template syntax. The following variables are available:

Variable	Description
{{.Detail}}	Summary (log message or metric values)
{{.Container.Name}}	Container name
{{.Container.Image}}	Container image
{{.Container.HostName}}	Docker host name
{{.Container.State}}	Container state
{{.Log.Message}}	Log message content
{{.Log.Level}}	Log level
{{.Log.Timestamp}}	Log timestamp
{{.Log.Stream}}	Stream type (stdout/stderr)
{{.Stat.CPUPercent}}	CPU usage percentage
{{.Stat.MemoryPercent}}	Memory usage percentage
{{.Stat.MemoryUsage}}	Memory usage in bytes
{{.Subscription.Name}}	Alert rule name

Tip

Use the Test button to verify your webhook is working before saving.

Dozzle Cloud

You can also send alerts to Dozzle Cloud for centralized monitoring across multiple Dozzle instances. See the Dozzle Cloud guide for more details.

Creating an Alert

Navigate to the Notifications page and click Add Alert. You'll need to configure:

Container Expression

The container expression selects which containers to monitor. Available properties:

Property	Type	Example
name	string	name contains "api"
image	string	image == "nginx:latest"
state	string	state == "running"
health	string	health == "unhealthy"
hostName	string	hostName == "prod-host"
labels	map	labels["env"] == "production"

You can combine conditions with && (AND), || (OR), and ! (NOT):

name contains "api" && labels["env"] == "production"

Log Expression

The log expression filters which log messages trigger the alert. Available properties:

Property	Type	Example
message	string/map	message contains "error"
level	string	level == "error"
stream	string	stream == "stderr"
type	string	type == "complex"

For JSON logs, you can access nested fields using dot notation:

message.status >= 500 && message.path contains "/api"

Supported string operators include contains, startsWith, endsWith, and matches (regex).

Examples

Alert on all errors from production containers:

Container: labels["env"] == "production"
Log:       level == "error"

Alert on HTTP 5xx errors from API containers:

Container: name contains "api"
Log:       message.status >= 500

Alert on any stderr output from a specific image:

Container: image startsWith "myapp/"
Log:       stream == "stderr"

Note

The alert editor includes autocomplete and real-time validation. You can preview matched containers and logs before saving.

Managing Alerts

From the Notifications page, you can:

• Enable/disable alerts without deleting them
• Edit alert expressions and destinations
• View statistics including trigger count, matched containers, and last triggered time
• Delete alerts that are no longer needed