### Install Mike

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/README.md

Install the Mike tool using pip. This is the first step to enable versioned documentation.

```bash
pip install mike
```

--------------------------------

### Install MkDocs Dependencies

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/README.md

Installs the necessary Python packages for building and serving the documentation. Ensure your virtual environment is activated.

```bash
pip install -r build/mkdocs/docs-requirements.txt
```

--------------------------------

### Check Go Version

Source: https://github.com/nicholas-fedor/watchtower/blob/main/CONTRIBUTING.md

Verify your installed Go version. Ensure you have the latest version installed.

```bash
go version
```

--------------------------------

### Docker Compose Example with Custom Template

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/templates/index.md

This example demonstrates how to configure Watchtower with a custom notification template using Docker Compose.

```yaml
services:
  watchtower:
    image: watchtower-image
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
    environment:
      WATCHTOWER_NOTIFICATION_REPORT: "true"
      WATCHTOWER_NOTIFICATION_URL: >
        discord://token@channel
        slack://watchtower@token-a/token-b/token-c
      WATCHTOWER_NOTIFICATION_TEMPLATE: |
        {{- if .Report -}}
          {{- with .Report -}}
        {{len .Scanned}} Scanned, {{len .Updated}} Updated, {{len .Restarted}} Restarted, {{len .Failed}} Failed
        {{- if ( or .Updated .Restarted .Failed ) -}}
            {{- range .Updated -}}
        - {{.Name}} ({{.ImageName}}): {{.CurrentImageID.ShortID}} updated to {{.LatestImageID.ShortID}}
            {{- end -}}
            {{- range .Fresh -}}
        - {{.Name}} ({{.ImageName}}): {{.State}}
            {{- end -}}
            {{- range .Restarted -}}
        - {{.Name}} ({{.ImageName}}): {{.State}}
            {{- end -}}
            {{- range .Skipped -}}
        - {{.Name}} ({{.ImageName}}): {{.State}}: {{.Error}}
            {{- end -}}
            {{- range .Failed -}}
        - {{.Name}} ({{.ImageName}}): {{.State}}: {{.Error}}
            {{- end -}}
        {{- end -}}
          {{- end -}}
        {{- if .Entries -}}

        Logs:
        {{- end -}}
        {{- range .Entries -}}{{.Time.Format "2006-01-02T15:04:05Z07:00"}} [{{.Level}}] {{.Message}}{{"\n"}}{{- end -}}
        {{- end -}}
```

--------------------------------

### Docker CLI Example with Custom Template

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/templates/index.md

This example shows how to run Watchtower using the Docker CLI and set a custom notification template via an environment variable.

```bash
docker run -d \
  --name watchtower \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -e WATCHTOWER_NOTIFICATION_REPORT="true" \
  -e WATCHTOWER_NOTIFICATION_TEMPLATE="\
    {{- if .Report -}} \
      {{- with .Report -}} \
    {{len .Scanned}} Scanned, {{len .Updated}} Updated, {{len .Restarted}} Restarted, {{len .Failed}} Failed \
    {{- if ( or .Updated .Restarted .Failed ) -}} \
          {{- range .Updated -}} \
    - {{.Name}} ({{.ImageName}}): {{.CurrentImageID.ShortID}} updated to {{.LatestImageID.ShortID}} \
          {{- end -}} \
          {{- range .Fresh -}} \
    - {{.Name}} ({{.ImageName}}): {{.State}} \
          {{- end -}} \
          {{- range .Restarted -}} \
    - {{.Name}} ({{.ImageName}}): {{.State}} \
          {{- end -}} \
          {{- range .Skipped -}} \
    - {{.Name}} ({{.ImageName}}): {{.State}}: {{.Error}} \
          {{- end -}} \
          {{- range .Failed -}} \
    - {{.Name}} ({{.ImageName}}): {{.State}}: {{.Error}} \
          {{- end -}} \
    {{- end -}} \
      {{- end -}} \
    {{- if .Entries -}} \
 \
    Logs: \
    {{- end -}} \
    {{- range .Entries -}}{{.Time.Format \"2006-01-02T15:04:05Z07:00\"}} [{{.Level}}] {{.Message}}{{`\n`}}{{- end -}} \
    {{- end -}} \
    " \
  watchtower-image
```

--------------------------------

### Example Output for Found New Image

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/templates/index.md

Example output for a log entry with msg="Found new image" when using the simple template.

```text
Found new image: repo/image:latest (abcdef123456)
```

--------------------------------

### Docker Compose Configuration with HTTP API Enabled

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/http-api/index.md

Example Docker Compose setup for Watchtower, enabling the HTTP API for updates and metrics, and configuring port mappings.

```yaml
services:
  app-monitored-by-watchtower:
    image: myapps/monitored-by-watchtower
    labels:
      - "com.centurylinklabs.watchtower.enable=true"

  watchtower:
    image: nickfedor/watchtower
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
    command: --http-api-update --http-api-metrics
    environment:
      - WATCHTOWER_HTTP_API_TOKEN=mytoken
    labels:
      - "com.centurylinklabs.watchtower.enable=false"
    ports:
      - 8080:8080
    restart: unless-stopped
```

--------------------------------

### Example Notification Output

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/templates/index.md

This is an example of the output generated by the default report template for a session with one updated container and an error log.

```text
5 Scanned, 1 Updated, 1 Restarted, 0 Failed
- /container (repo/image:latest): abcdef12 updated to 34567890
- /restarted-container (repo/image:latest): Restarted

Logs:
2025-08-20T06:00:13-07:00 [error] Operation failed. Try again later.
```

--------------------------------

### Download Watchtower Binary for Windows (amd64)

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/getting-started/installation/index.md

This PowerShell script downloads, extracts, and installs the Watchtower executable for Windows (amd64) to the current directory. It checks for successful installation.

```powershell
iwr (iwr https://api.github.com/repos/nicholas-fedor/watchtower/releases/latest | ConvertFrom-Json).assets.where({$_.name -like "*windows_amd64*.zip"}).browser_download_url -OutFile watchtower.zip; Add-Type -AssemblyName System.IO.Compression.FileSystem; $zip = [System.IO.Compression.ZipFile]::OpenRead("$PWD\watchtower.zip"); $zip.Entries | Where-Object {$_.Name -eq 'watchtower.exe'} | ForEach-Object {[System.IO.Compression.ZipFileExtensions]::ExtractToFile($_, "$PWD\watchtower.exe", $true)}; $zip.Dispose(); Remove-Item watchtower.zip; if (Test-Path ".\watchtower.exe") { Write-Host "Successfully installed watchtower.exe to current directory" } else { Write-Host "Failed to install watchtower.exe" }
```

--------------------------------

### Declare Multiple Dependencies

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/linked-containers/index.md

This example demonstrates how to declare multiple dependencies for a service using the Watchtower depends-on label.

```dockerfile
LABEL com.centurylinklabs.watchtower.depends-on="database,cache,queue"
```

--------------------------------

### Define Post-update Hook

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/lifecycle-hooks/index.md

Set up a post-update hook using a Docker label. This command runs after the new container has started. The monitored container must have the necessary tools installed.

```dockerfile
LABEL com.centurylinklabs.watchtower.lifecycle.post-update="echo 'Container updated successfully'"
```

--------------------------------

### Docker Run Commands for Legacy Links

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/linked-containers/index.md

Demonstrates starting a database and a web application with a legacy Docker link. Watchtower respects these links for update sequencing.

```bash
docker run -d --name mysql mysql:8.0
```

```bash
docker run -d --name webapp --link mysql:db nginx
```

--------------------------------

### Example Gotify Configuration using Docker CLI

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/overview/index.md

Configure Gotify notifications by providing a `gotify://` URL directly in the Docker CLI command. This is the recommended method.

```bash
docker run -d \
  --name watchtower \
  -v /var/run/docker.sock:/var/run/docker.sock \
  nickfedor/watchtower \
  --notification-url "gotify://my.gotify.tld/SuperSecretToken"
```

--------------------------------

### Docker Compose for Private Registry Monitoring

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/getting-started/usage/index.md

A complete docker-compose.yml file to run a container from a private registry (GitHub Registry example) and monitor it with Watchtower. This example also customizes the update interval.

```yaml
version: "3" 
services:
  cavo:
    image: ghcr.io/<org>/<image>:<tag>
    ports:
      - "443:3443"
      - "80:3080"
  watchtower:
    image: nickfedor/watchtower
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - /root/.docker/config.json:/config.json
    command: --interval 30
```

--------------------------------

### Build Documentation Locally

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/README.md

Builds the static documentation site locally for validation. This command checks for errors without starting a server.

```bash
mkdocs build --config-file build/mkdocs/mkdocs.yaml
```

--------------------------------

### Create and Activate Python Virtual Environment

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/README.md

Sets up an isolated Python environment for managing project dependencies. Activate it before installing packages.

```bash
python -m venv watchtower-docs
. watchtower-docs/bin/activate
```

--------------------------------

### Configure Single Global Mirror in daemon.json

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/registry-mirrors/index.md

Example of configuring a single global registry mirror within the Docker daemon's configuration file.

```json
{
    "registry-mirrors": [
        "https://docker-mirror.company.com"
    ]
}
```

--------------------------------

### Example MSTeams Configuration using Docker CLI

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/overview/index.md

Configure Microsoft Teams notifications using the `teams://` URL format with Docker CLI. This is the recommended method.

```bash
docker run -d \
  --name watchtower \
  -v /var/run/docker.sock:/var/run/docker.sock \
  nickfedor/watchtower \
  --notification-url "teams:?color=%23406170&host=https://default.environment.api.powerplatform.com/powerautomate/automations/direct/workflows/abc123/triggers/manual/paths/invoke?api-version=1&sp=%2Ftriggers%2Fmanual%2Frun&sv=1.0&sig=XXXXXXXX"
```

--------------------------------

### Clone Watchtower Repository

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/README.md

Use this command to clone the Watchtower repository locally. Ensure you have Git installed.

```bash
git clone https://github.com/nicholas-fedor/watchtower.git
cd watchtower
```

--------------------------------

### Enable Split Notifications Per Container

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/overview/index.md

Example demonstrating how to configure Watchtower to send individual notifications for each updated container.

```bash
docker run -d \
  --name watchtower \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -e WATCHTOWER_NOTIFICATION_URL="slack://hook:xxxx-yyyy-zzzz@webhook?botname=watchtower" \
  -e WATCHTOWER_NOTIFICATION_SPLIT_BY_CONTAINER=true \
  nickfedor/watchtower
```

--------------------------------

### Example MSTeams Configuration using Docker Compose

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/overview/index.md

Configure Microsoft Teams notifications using the `teams://` URL format with Docker Compose. This is the recommended method.

```yaml
services:
  watchtower:
    image: nickfedor/watchtower:latest
    environment:
      WATCHTOWER_NOTIFICATION_URL: "teams:?color=%23406170&host=https://default.environment.api.powerplatform.com/powerautomate/automations/direct/workflows/abc123/triggers/manual/paths/invoke?api-version=1&sp=%2Ftriggers%2Fmanual%2Frun&sv=1.0&sig=XXXXXXXX"
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
```

--------------------------------

### Watchtower Notification Summary Log

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/overview/index.md

Example log output from Watchtower indicating the successfully parsed notification services upon startup.

```text
time="2026-01-28T16:07:24+01:00" level=info msg="Using notifications: discord, telegram"
```

--------------------------------

### Example Legacy Email Notification Configuration (Docker CLI Flags)

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/overview/index.md

This snippet demonstrates the legacy configuration for email notifications using command-line flags with Docker CLI.

```bash
docker run -d \
  --name watchtower \
  -v /var/run/docker.sock:/var/run/docker.sock \
  nickfedor/watchtower \
  --notifications email \
  --notification-email-server smtp.example.com \
  --notification-email-server-port 587 \
  --notification-email-server-user user@example.com \
  --notification-email-server-password secret \
  --notification-email-from sender@example.com \
  --notification-email-to recipient@example.com
```

--------------------------------

### Example Legacy Email Notification Configuration (Docker Compose)

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/overview/index.md

This snippet shows the legacy configuration for email notifications using Docker Compose.

```yaml
services:
  watchtower:
    image: nickfedor/watchtower:latest
    environment:
      WATCHTOWER_NOTIFICATIONS: email
      WATCHTOWER_NOTIFICATION_EMAIL_SERVER: smtp.example.com
      WATCHTOWER_NOTIFICATION_EMAIL_SERVER_PORT: 587
      WATCHTOWER_NOTIFICATION_EMAIL_SERVER_USER: user@example.com
      WATCHTOWER_NOTIFICATION_EMAIL_SERVER_PASSWORD: secret
      WATCHTOWER_NOTIFICATION_EMAIL_FROM: sender@example.com
      WATCHTOWER_NOTIFICATION_EMAIL_TO: recipient@example.com
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
```

--------------------------------

### Monitor a Container with a Per-Container Cooldown via Docker CLI

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/image-cooldown/index.md

Start a container and apply a specific cooldown delay of 72 hours using a label.

```bash
docker run -d \
  --name myapp \
  --label=com.centurylinklabs.watchtower.cooldown-delay="72h" \
  myorg/myapp:latest

```

--------------------------------

### Example Docker Compose Deployment with Go Hook

Source: https://github.com/nicholas-fedor/watchtower/blob/main/examples/lifecycle-hooks/synology-stop/README.md

Deploy Watchtower and a service (e.g., nginx) using Docker Compose. The service is configured to use the Go implementation of the Synology stop hook as a pre-update lifecycle hook.

```yaml
services:
    watchtower:
        image: nicholas-fedor/watchtower
        volumes:
            - /var/run/docker.sock:/var/run/docker.sock
        environment:
            WATCHTOWER_LIFECYCLE_HOOKS: true
        restart: unless-stopped

    nginx:
        image: nginx:latest
        volumes:
            - ./Scripts/synology-stop:/synology-stop:ro
        ports:
            - 8080:80
        labels:
            - com.centurylinklabs.watchtower.lifecycle.pre-update: "/synology-stop"
        environment:
            - SYNO_URL=http://192.168.1.100:5000
            - SYNO_USER=watchtower
            - SYNO_PASS=supersecretpassword
```

--------------------------------

### Download Watchtower Binary for Linux (amd64)

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/getting-started/installation/index.md

This Bash script downloads and extracts the Watchtower binary for Linux (amd64) to the current directory. It verifies if the binary was successfully installed.

```bash
curl -L $(curl -s https://api.github.com/repos/nicholas-fedor/watchtower/releases/latest | grep -o 'https://[^"']*) | tar -xz -C . watchtower && if [ -f ./watchtower ]; then echo "Successfully installed watchtower to current directory"; else echo "Failed to install watchtower"; fi
```

--------------------------------

### Backup Logic Based on Labels

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/lifecycle-hooks/index.md

Customize backup behavior using container labels. This example uses a 'backup-type' label to determine if a full, incremental, or default backup should be performed. Requires jq.

```bash
#!/bin/bash
BACKUP_TYPE=$(echo $WT_CONTAINER | jq -r '.labels["com.centurylinklabs.watchtower.backup-type"] // "default"')
case $BACKUP_TYPE in
    "full")
        echo "Performing full backup"
        # Full backup logic
        ;;
    "incremental")
        echo "Performing incremental backup"
        # Incremental backup logic
        ;;
    *)
        echo "Performing default backup"
        # Default backup logic
        ;;
esac
```

--------------------------------

### Example Gotify Configuration using Docker Compose

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/overview/index.md

Configure Gotify notifications using Docker Compose by setting the `WATCHTOWER_NOTIFICATION_URL` environment variable with a `gotify://` URL. This is the recommended method.

```yaml
services:
  watchtower:
    image: nickfedor/watchtower:latest
    environment:
      WATCHTOWER_NOTIFICATION_URL: "gotify://my.gotify.tld/SuperSecretToken"
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
```

--------------------------------

### Mount config.json in Docker Run

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/configuration/private-registries/index.md

Mount the created `config.json` file into the Watchtower container when starting it with `docker run`.

```bash
docker run [...] -v <PATH>/config.json:/config.json nickfedor/watchtower
```

--------------------------------

### Example Legacy Email Notification Configuration (Docker CLI Env Vars)

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/overview/index.md

This snippet shows the legacy configuration for email notifications using environment variables with Docker CLI.

```bash
docker run -d \
  --name watchtower \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -e WATCHTOWER_NOTIFICATIONS=email \
  -e WATCHTOWER_NOTIFICATION_EMAIL_SERVER=smtp.example.com \
  -e WATCHTOWER_NOTIFICATION_EMAIL_SERVER_PORT=587 \
  -e WATCHTOWER_NOTIFICATION_EMAIL_SERVER_USER=user@example.com \
  -e WATCHTOWER_NOTIFICATION_EMAIL_SERVER_PASSWORD=secret \
  -e WATCHTOWER_NOTIFICATION_EMAIL_FROM=sender@example.com \
  -e WATCHTOWER_NOTIFICATION_EMAIL_TO=recipient@example.com \
  nickfedor/watchtower
```

--------------------------------

### Monitor nginx:latest Container

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/getting-started/overview/index.md

This example shows a container running the 'nginx:latest' image. Watchtower will update this container if the 'latest' tag on the nginx image is updated. Be aware that 'latest' can include breaking changes.

```bash
CONTAINER ID   IMAGE          STATUS          PORTS                    NAMES
abc123def456   nginx:latest   Up 10 minutes   0.0.0.0:80->80/tcp       webserver
```

--------------------------------

### Start Watchtower with a Global Cooldown via Docker CLI

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/image-cooldown/index.md

Run Watchtower as a container and set a global cooldown delay of 24 hours using an environment variable.

```bash
docker run -d \
  --name watchtower \
  -e WATCHTOWER_COOLDOWN_DELAY=24h \
  -v /var/run/docker.sock:/var/run/docker.sock \
  nickfedor/watchtower

```

--------------------------------

### Run Watchtower Container

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/getting-started/usage/index.md

Start the Watchtower container in detached mode. Ensure the Docker socket is mounted for Watchtower to interact with the Docker API.

```bash
docker run -d \
  --name watchtower \
  -v /var/run/docker.sock:/var/run/docker.sock \
  --restart unless-stopped \
  nickfedor/watchtower
```

--------------------------------

### Monitor nginx:1.29 Container

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/getting-started/overview/index.md

This example demonstrates a container using a specific semantic version tag, 'nginx:1.29'. Watchtower will update this container only when new patch versions within the 1.29 series are released and tagged as '1.29'.

```bash
CONTAINER ID   IMAGE          STATUS          PORTS                    NAMES
def456ghi789   nginx:1.29     Up 10 minutes   0.0.0.0:80->80/tcp       webserver
```

--------------------------------

### Serve All Deployed Versions Locally

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/README.md

Serve all deployed versions of the documentation locally for testing version switching and navigation. Ensure 'mike deploy' has been run first.

```bash
mike serve --config-file build/mkdocs/mkdocs.yaml
```

--------------------------------

### Build Application

Source: https://github.com/nicholas-fedor/watchtower/blob/main/CONTRIBUTING.md

Compile and package the Watchtower executable binary. Ensure GO111MODULE is set if needed.

```bash
go build
```

--------------------------------

### Serve Single Version Locally with MkDocs

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/README.md

Serve the current documentation state locally for quick previews during development without versioning features. This does not require deployment commits.

```bash
mkdocs serve --config-file build/mkdocs/mkdocs.yaml
```

--------------------------------

### Backup Logic Based on Container State

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/lifecycle-hooks/index.md

Implement conditional backup logic based on container names or other state information. This example checks if a container is part of a 'prod' environment.

```bash
#!/bin/bash
CONTAINER_NAME=$(echo $WT_CONTAINER | jq -r '.name')

# Check if this is a production container
if [[ $CONTAINER_NAME == *"prod"* ]]; then
    echo "Production container - extra caution"
    # Additional safety checks
else
    echo "Non-production container - proceeding"
fi
```

--------------------------------

### Monitor pihole:2023.11 Container

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/getting-started/overview/index.md

This example shows a container running 'pihole/pihole:2023.11', illustrating a date-based tagging scheme. Watchtower will update this container to the latest patch within the '2023.11' period but not to subsequent monthly or yearly releases.

```bash
CONTAINER ID   IMAGE               STATUS          PORTS                    NAMES
ghi789jkl012   pihole/pihole:2023.11   Up 10 minutes   0.0.0.0:8080->80/tcp   pihole
```

--------------------------------

### Build Go Binary for Synology Hook

Source: https://github.com/nicholas-fedor/watchtower/blob/main/examples/lifecycle-hooks/synology-stop/README.md

Build the Go binary for the Synology pre-update hook. Ensure you are in the correct directory and specify the target OS and architecture.

```bash
cd examples/lifecycle-hooks/synology-stop
GOOS=linux GOARCH=arm64 go build -o synology-stop synology-stop.go
```

--------------------------------

### Build and Run Hook for Testing

Source: https://github.com/nicholas-fedor/watchtower/blob/main/examples/lifecycle-hooks/synology-stop/README.md

Build the Go hook binary and make it executable, then run Watchtower in one-off mode to trigger an update for a specified container, testing the lifecycle hook.

```bash
go build -o synology-stop synology-stop.go && chmod +x synology-stop
docker run --rm nicholas-fedor/watchtower --run-once nginx
```

--------------------------------

### Signal URL Format - Group Only

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/overview/index.md

Example of a Signal notification URL format for sending to a specific group.

```plaintext
signal://localhost:8080/+1234567890/group.abcdefghijklmnop=
```

--------------------------------

### Get Stop Signal in Python

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/lifecycle-hooks/index.md

Parses the WT_CONTAINER environment variable as JSON to access the stop signal.

```python
import os
import json

container_info = json.loads(os.environ['WT_CONTAINER'])
print(f"Stop signal: {container_info['stop_signal']}")
```

--------------------------------

### Build Template Preview Script

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/README.md

Makes the template preview build script executable and then runs it. This script is part of the documentation build process.

```bash
chmod +x scripts/build-tplprev.sh
./scripts/build-tplprev.sh
```

--------------------------------

### Get Image Name in Python

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/lifecycle-hooks/index.md

Parses the WT_CONTAINER environment variable as JSON to access the image name.

```python
import os
import json

container_info = json.loads(os.environ['WT_CONTAINER'])
print(f"Image: {container_info['image_name']}")
```

--------------------------------

### Deploy Version Locally with Mike

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/README.md

Build and commit documentation to a local Git branch for a specific version. Use --config-file to specify the mkdocs.yaml path. The --push flag is required to push to a remote repository.

```bash
mike deploy <version> --config-file build/mkdocs/mkdocs.yaml
```

```bash
mike deploy <version> <alias> --config-file build/mkdocs/mkdocs.yaml
```

--------------------------------

### Get Container ID in Python

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/lifecycle-hooks/index.md

Parses the WT_CONTAINER environment variable as JSON to access the container ID.

```python
import os
import json

container_info = json.loads(os.environ['WT_CONTAINER'])
print(f"Container ID: {container_info['id']}")
```

--------------------------------

### Get Container Name in Python

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/lifecycle-hooks/index.md

Parses the WT_CONTAINER environment variable as JSON to access the container name.

```python
import os
import json

container_info = json.loads(os.environ['WT_CONTAINER'])
print(f"Processing container: {container_info['name']}")
```

--------------------------------

### Get Stop Signal in Bash

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/lifecycle-hooks/index.md

Extracts the stop signal from the WT_CONTAINER environment variable using jq.

```bash
#!/bin/bash
SIGNAL=$(echo $WT_CONTAINER | jq -r '.stop_signal')
echo "Stop signal: $SIGNAL"
```

--------------------------------

### Build Production Binaries Locally

Source: https://github.com/nicholas-fedor/watchtower/blob/main/CONTRIBUTING.md

Use this command to build Watchtower binaries and archives for local testing in snapshot mode. It utilizes the production GoReleaser configuration.

```bash
goreleaser release --config build/goreleaser/prod.yml --snapshot --clean
```

--------------------------------

### Get Image Name in Bash

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/lifecycle-hooks/index.md

Extracts the image name from the WT_CONTAINER environment variable using jq.

```bash
#!/bin/bash
IMAGE=$(echo $WT_CONTAINER | jq -r '.image_name')
echo "Image: $IMAGE"
```

--------------------------------

### Get Container ID in Bash

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/lifecycle-hooks/index.md

Extracts the container ID from the WT_CONTAINER environment variable using jq.

```bash
#!/bin/bash
CONTAINER_ID=$(echo $WT_CONTAINER | jq -r '.id')
echo "Container ID: $CONTAINER_ID"
```

--------------------------------

### Get Container Name in Bash

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/lifecycle-hooks/index.md

Extracts the container name from the WT_CONTAINER environment variable using jq.

```bash
#!/bin/bash
CONTAINER_NAME=$(echo $WT_CONTAINER | jq -r '.name')
echo "Processing container: $CONTAINER_NAME"
```

--------------------------------

### Default Simple Template

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/templates/index.md

This template processes info-level log entries in real-time, formatting key update events. It sends each event immediately, mimicking a step-by-step log.

```go
{{- range $i, $e := . -}}
{{- if $i}}{{- println -}}{{- end -}}
{{- $msg := $e.Message -}}
{{- if eq $msg "Found new image" -}}
    Found new image: {{$e.Data.image}} ({{with $e.Data.new_id}}{{.}}{{else}}unknown{{end}})
{{- else if eq $msg "Stopping container" -}}
    Stopped stale container: {{$e.Data.container}} ({{with $e.Data.id}}{{.}}{{else}}unknown{{end}})
{{- else if eq $msg "Started new container" -}}
    Started new container: {{$e.Data.container}} ({{with $e.Data.new_id}}{{.}}{{else}}unknown{{end}})
{{- else if eq $msg "Removing image" -}}
    Removed stale image: {{with $e.Data.image_id}}{{.}}{{else}}unknown{{end}}
{{- else if eq $msg "Detected multiple Watchtower instances - initiating cleanup" -}}
    Detected {{$e.Data.count}} Watchtower instances - initiating cleanup
{{- else if $e.Data -}}
    {{$msg}} | {{range $k, $v := $e.Data -}}{{$k}}={{$v}} {{- end}}
{{- else -}}
    {{$msg}}
{{- end -}}
{{- end -}}
```

--------------------------------

### Build Local Watchtower Docker Image

Source: https://github.com/nicholas-fedor/watchtower/blob/main/CONTRIBUTING.md

Build a Watchtower Docker image from your current local Watchtower files. Ensure you are in the root directory of the project.

```bash
docker build . -f build/docker/Dockerfile.self-local -t nickfedor/watchtower # to build an image from local files
```

--------------------------------

### Sending Signal Notifications with Attachments

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/overview/index.md

Example of sending a Signal message with base64-encoded attachments using the shoutrrr CLI.

```bash
shoutrrr send "signal://localhost:8080/+1234567890/+0987654321" \
  "Message with attachment" \
  --attachments "base64data1,base64data2"
```

--------------------------------

### Simple Template for Template Preview Tool

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/templates/index.md

This template is adapted for the Template Preview Tool, matching its data structure by ranging over `.Entries`. It formats log entries similarly to the default simple template.

```go
{{- range $i, $e := .Entries -}}
{{- if $i}}{{- println -}}{{- end -}}
{{- $msg := $e.Message -}}
{{- if eq $msg "Found new image" -}}
    Found new image: {{$e.Data.image}} ({{with $e.Data.new_id}}{{.}}{{else}}unknown{{end}})
{{- else if eq $msg "Stopping container" -}}
    Stopped stale container: {{$e.Data.container}} ({{with $e.Data.id}}{{.}}{{else}}unknown{{end}})
{{- else if eq $msg "Started new container" -}}
    Started new container: {{$e.Data.container}} ({{with $e.Data.new_id}}{{.}}{{else}}unknown{{end}})
{{- else if eq $msg "Removing image" -}}
    Removed stale image: {{with $e.Data.image_id}}{{.}}{{else}}unknown{{end}}
{{- else if eq $msg "Detected multiple Watchtower instances - initiating cleanup" -}}
    Detected {{$e.Data.count}} Watchtower instances - initiating cleanup
{{- else if $e.Data -}}
    {{$msg}} | {{range $k, $v := $e.Data -}}{{$k}}={{$v}} {{- end}}
{{- else -}}
    {{$msg}}
{{- end -}}
{{- end -}}
```

--------------------------------

### Get Stop Signal in Go

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/lifecycle-hooks/index.md

Unmarshals the WT_CONTAINER environment variable into a Go struct to access the stop signal.

```go
package main

import (
    "encoding/json"
    "fmt"
    "os"
)

func main() {
    var container struct {
        StopSignal string `json:"stop_signal"`
    }

    if err := json.Unmarshal([]byte(os.Getenv("WT_CONTAINER")), &container); err != nil {
        panic(err)
    }

    fmt.Printf("Stop signal: %s\n", container.StopSignal)
}
```

--------------------------------

### Execute Pre-Update Script via Labels in Python

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/lifecycle-hooks/index.md

Retrieves and executes a backup script from the 'com.centurylinklabs.watchtower.lifecycle.pre-update' label.

```python
import os
import json

container_info = json.loads(os.environ['WT_CONTAINER'])
backup_script = container_info['labels'].get('com.centurylinklabs.watchtower.lifecycle.pre-update')
if backup_script:
    print(f"Running backup: {backup_script}")
    # Execute backup_script
```

--------------------------------

### Get Image Name in Go

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/lifecycle-hooks/index.md

Unmarshals the WT_CONTAINER environment variable into a Go struct to access the image name.

```go
package main

import (
    "encoding/json"
    "fmt"
    "os"
)

func main() {
    var container struct {
        ImageName string `json:"image_name"`
    }

    if err := json.Unmarshal([]byte(os.Getenv("WT_CONTAINER")), &container); err != nil {
        panic(err)
    }

    fmt.Printf("Image: %s\n", container.ImageName)
}
```

--------------------------------

### Generate Mocks

Source: https://github.com/nicholas-fedor/watchtower/blob/main/CONTRIBUTING.md

Generate mock implementations for Watchtower's interfaces using Mockery. Run this from the root directory.

```bash
make mocks
```

--------------------------------

### Get Container ID in Go

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/lifecycle-hooks/index.md

Unmarshals the WT_CONTAINER environment variable into a Go struct to access the container ID.

```go
package main

import (
    "encoding/json"
    "fmt"
    "os"
)

func main() {
    var container struct {
        ID string `json:"id"`
    }

    if err := json.Unmarshal([]byte(os.Getenv("WT_CONTAINER")), &container); err != nil {
        panic(err)
    }

    fmt.Printf("Container ID: %s\n", container.ID)
}
```

--------------------------------

### Get Container Name in Go

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/lifecycle-hooks/index.md

Unmarshals the WT_CONTAINER environment variable into a Go struct to access the container name.

```go
package main

import (
    "encoding/json"
    "fmt"
    "os"
)

func main() {
    var container struct {
        Name string `json:"name"`
    }

    if err := json.Unmarshal([]byte(os.Getenv("WT_CONTAINER")), &container); err != nil {
        panic(err)
    }

    fmt.Printf("Processing container: %s\n", container.Name)
}
```

--------------------------------

### Run Docker Compose

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/quickstart/index.md

Execute this command in the directory containing your docker-compose.yaml file to start Watchtower in detached mode.

```bash
docker compose up -d
```

--------------------------------

### Execute Pre-Update Script via Labels in Bash

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/lifecycle-hooks/index.md

Retrieves and executes a backup script defined in the 'com.centurylinklabs.watchtower.lifecycle.pre-update' label.

```bash
#!/bin/bash
BACKUP_SCRIPT=$(echo $WT_CONTAINER | jq -r '.labels["com.centurylinklabs.watchtower.lifecycle.pre-update"]')
if [ -n "$BACKUP_SCRIPT" ]; then
    echo "Running backup: $BACKUP_SCRIPT"
    $BACKUP_SCRIPT
fi
```

--------------------------------

### Signal URL Format - With Authentication

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/overview/index.md

Example of a Signal notification URL format including basic HTTP authentication credentials.

```plaintext
signal://user:password@localhost:8080/+1234567890/+0987654321
```

--------------------------------

### Execute Pre-Update Script via Labels in Go

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/lifecycle-hooks/index.md

Retrieves and executes a backup script from the 'com.centurylinklabs.watchtower.lifecycle.pre-update' label by unmarshalling the WT_CONTAINER JSON.

```go
package main

import (
    "encoding/json"
    "fmt"
    "os"
)

func main() {
    var container struct {
        Labels map[string]string `json:"labels"`
    }

    if err := json.Unmarshal([]byte(os.Getenv("WT_CONTAINER")), &container); err != nil {
        panic(err)
    }

    if backupScript, exists := container.Labels["com.centurylinklabs.watchtower.lifecycle.pre-update"]; exists {
        fmt.Printf("Running backup: %s\n", backupScript)
        // Execute backupScript
    }
}
```

--------------------------------

### Database Backup and Migration Dockerfile

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/lifecycle-hooks/index.md

Configure pre-update backup and post-update migration scripts in a Dockerfile.

```dockerfile
FROM postgres:13

# Pre-update: Create backup before stopping
LABEL com.centurylinklabs.watchtower.lifecycle.pre-update="/usr/local/bin/backup.sh"
LABEL com.centurylinklabs.watchtower.lifecycle.pre-update-timeout="10"

# Post-update: Run migrations after starting new version
LABEL com.centurylinklabs.watchtower.lifecycle.post-update="/usr/local/bin/migrate.sh"
LABEL com.centurylinklabs.watchtower.lifecycle.post-update-timeout="15"

COPY backup.sh migrate.sh /usr/local/bin/
RUN chmod +x /usr/local/bin/backup.sh /usr/local/bin/migrate.sh
```

--------------------------------

### Signal URL Format - Basic

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/overview/index.md

Example of a basic Signal notification URL format for sending to a single phone number.

```plaintext
signal://localhost:8080/+1234567890/+0987654321
```

--------------------------------

### Signal URL Format - With API Token

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/overview/index.md

Example of a Signal notification URL format using an API token for Bearer authentication.

```plaintext
signal://localhost:8080/+1234567890/+0987654321?token=YOUR_API_TOKEN
```

--------------------------------

### Signal URL Format - Multiple Recipients

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/overview/index.md

Example of a Signal notification URL format for sending to multiple phone numbers and a group.

```plaintext
signal://localhost:8080/+1234567890/+0987654321/+1123456789/group.testgroup
```

--------------------------------

### Docker Commands for ECR Credential Helper

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/configuration/private-registries/index.md

Commands to create a Docker volume, build the ECR credential helper image, and run it to store the helper binary in the volume.

```bash
docker volume create helper
```

```bash
docker build -t aws-ecr-dock-cred-helper .
```

```bash
docker run  -d --rm --name aws-cred-helper \
  --volume helper:/go/bin aws-ecr-dock-cred-helper
```

--------------------------------

### Watchtower Container Information Endpoint Response

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/http-api/index.md

Example JSON response from the /v1/containers endpoint, detailing watched containers, their images, and digests.

```json
{
    "containers": [
        {
            "name": "nginx",
            "image": "nginx:latest",
            "image_id": "sha256:1111...",
            "digest": "sha256:2222..."
        }
    ],
    "count": 1,
    "timestamp": "2025-01-20T11:30:45Z",
    "api_version": "v1"
}
```

--------------------------------

### Format Code

Source: https://github.com/nicholas-fedor/watchtower/blob/main/CONTRIBUTING.md

Format the codebase using the Makefile target. This utilizes Golangci-lint for formatting.

```bash
make fmt
```

--------------------------------

### Mount Docker config.json in Docker Run

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/configuration/private-registries/index.md

Mount the existing Docker configuration file (`.docker/config.json`) into the Watchtower container when starting it with `docker run`.

```bash
docker run [...] -v <PATH_TO_HOME_DIR>/.docker/config.json:/config.json nickfedor/watchtower
```

--------------------------------

### Legacy Docker Linking for Dependencies

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/linked-containers/index.md

For legacy Docker setups, Watchtower treats explicit links and `network_mode: service:container` as implicit dependencies.

```docker
# Container with explicit link
docker run --link database:db nginx
```

```docker
# Container using service network mode
docker run --network container:database nginx
```

--------------------------------

### Run Application

Source: https://github.com/nicholas-fedor/watchtower/blob/main/CONTRIBUTING.md

Execute the compiled Watchtower application. This is run outside of a container.

```bash
./watchtower
```

--------------------------------

### Watchtower Debugging Command

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/linked-containers/index.md

Enables debug logging for Watchtower to help diagnose dependency detection issues. This command should be run in an environment where Watchtower is already installed.

```bash
watchtower --debug
```

--------------------------------

### Run Watchtower with Automatic CPU Compatibility

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/configuration/arguments/index.md

Use this command to run Watchtower with automatic CPU compatibility detection, suitable for mixed Docker/Podman environments.

```bash
docker run -d \
    --name watchtower \
    -v /var/run/docker.sock:/var/run/docker.sock \
    nickfedor/watchtower \
    --cpu-copy-mode auto
```

--------------------------------

### Signal URL Format - Using HTTP

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/overview/index.md

Example of a Signal notification URL format explicitly disabling TLS for HTTP communication. Use only for local testing.

```plaintext
signal://localhost:8080/+1234567890/+0987654321?disabletls=yes
```

--------------------------------

### Download Docker Compose File (Bash)

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/quickstart/index.md

Use this Bash command to download the default Docker Compose file for Watchtower on Linux.

```bash
curl -L https://raw.githubusercontent.com/nicholas-fedor/watchtower/refs/heads/main/examples/default/docker-compose.yaml -o docker-compose.yaml
```

--------------------------------

### Email Notification via Docker Compose

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/overview/index.md

Configure email notifications within a Docker Compose setup by setting the WATCHTOWER_NOTIFICATION_URL environment variable in the docker-compose.yml file.

```yaml
services:
  watchtower:
    image: nickfedor/watchtower:latest
    environment:
    WATCHTOWER_NOTIFICATION_URL: smtp://user:secret@smtp.example.com:587/?fromaddress=sender@example.com&toaddresses=recipient@example.com
    volumes:
    - /var/run/docker.sock:/var/run/docker.sock
```

--------------------------------

### Docker CLI (Flags)

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/notifications/overview/index.md

Configure Watchtower to send Signal notifications using command-line flags in Docker.

```bash
docker run -d \
  --name watchtower \
  -v /var/run/docker.sock:/var/run/docker.sock \
  nickfedor/watchtower \
  --notification-url "signal://localhost:8080/+1234567890/+0987654321"
```

--------------------------------

### Create config.json for Private Registry

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/configuration/private-registries/index.md

Manually create a `config.json` file with base64 encoded credentials for a private registry.

```json
{
    "auths": {
        "<REGISTRY_NAME>": {
            "auth": "XXXXXXX"
        }
    }
}
```

--------------------------------

### Strip All CPU Limits for Compatibility

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/configuration/arguments/index.md

Use this command to strip all CPU limits, which can help avoid compatibility issues if CPU limits are causing problems.

```bash
docker run -d \
    --name watchtower \
    -v /var/run/docker.sock:/var/run/docker.sock \
    nickfedor/watchtower \
    --cpu-copy-mode none
```

--------------------------------

### Enable Container Management with Labels (Docker CLI)

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/configuration/container-selection/index.md

Use this snippet to enable Watchtower management for a specific container when using the Docker CLI.

```bash
docker run -d --label=com.centurylinklabs.watchtower.enable=true someimage
```

--------------------------------

### Build WASM Template Preview

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/README.md

Build script for compiling Go code to WebAssembly. It outputs tplprev.wasm and wasm_exec.js to the docs/assets/ directory.

```bash
scripts/build-tplprev.sh
```

--------------------------------

### Declare Explicit Dependencies with Label

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/linked-containers/index.md

Use the `com.centurylinklabs.watchtower.depends-on` label to explicitly declare dependencies when automatic detection is insufficient. This example shows how to declare dependencies on 'postgres' and 'redis' services.

```dockerfile
FROM nginx:latest

# Declare dependencies on database and cache services
LABEL com.centurylinklabs.watchtower.depends-on="postgres,redis"
```

```yaml
services:
  web:
    image: nginx
    labels:
      - com.centurylinklabs.watchtower.depends-on=postgres,redis
  postgres:
    image: postgres
  redis:
    image: redis
```

--------------------------------

### Download Docker Compose File (PowerShell)

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/quickstart/index.md

Use this PowerShell command to download the default Docker Compose file for Watchtower on Windows.

```powershell
iwr -Uri https://raw.githubusercontent.com/nicholas-fedor/watchtower/refs/heads/main/examples/default/docker-compose.yaml -OutFile docker-compose.yaml
```

--------------------------------

### Use Docker Hub Credentials with 2FA

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/getting-started/usage/index.md

Mount the host's Docker config file to provide credentials for Docker Hub when 2FA is enabled. This makes your `$HOME/.docker/config.json` available to the Watchtower container.

```bash
docker run -d \
  --name watchtower \
  -v $HOME/.docker/config.json:/config.json \
  -v /var/run/docker.sock:/var/run/docker.sock \
  --restart unless-stopped \
  nickfedor/watchtower container_to_watch --debug
```

--------------------------------

### Exclude Containers by Name Prefix using Regex

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/configuration/container-selection/index.md

Use the WATCHTOWER_DISABLE_CONTAINERS environment variable with a regex pattern to exclude containers that start with a specific prefix. This is useful for managing groups of containers.

```bash
docker run -d -e WATCHTOWER_DISABLE_CONTAINERS="web-.*" nickfedor/watchtower
```

--------------------------------

### Configure Server Certificate Extensions

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/configuration/secure-connections/index.md

Defines Subject Alternative Names (SAN) and extended key usage for the server certificate. Ensure `IP:10.10.10.20` is replaced with your host's actual IP and `$HOST` with the correct hostname.

```bash
echo "subjectAltName = DNS:$HOST,IP:10.10.10.20,IP:127.0.0.1" > extfile-server.cnf
```

```bash
echo "extendedKeyUsage = serverAuth" >> extfile-server.cnf
```

--------------------------------

### Programmatic Output (Porcelain) Argument

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/configuration/arguments/index.md

The --porcelain argument outputs session results in a machine-readable format, specified by VERSION. This is equivalent to setting several notification-related flags.

```text
Argument: --porcelain, -P
Environment Variable: WATCHTOWER_PORCELAIN
     Possible Values: v1
             Default: None
```

--------------------------------

### Explicit Dependency Declaration with Watchtower Label

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/linked-containers/index.md

Use the `com.centurylinklabs.watchtower.depends-on` label to explicitly declare dependencies. This label accepts a comma-separated list of container names that must be available before the current container starts.

```dockerfile
LABEL com.centurylinklabs.watchtower.depends-on="database,redis"
```

--------------------------------

### Docker Compose for Network Mode Dependencies

Source: https://github.com/nicholas-fedor/watchtower/blob/main/docs/advanced-features/linked-containers/index.md

Shows a Docker Compose setup where a sidecar container uses network mode dependent on the main application. Watchtower ensures the main app is updated before the sidecar.

```yaml
services:
  sidecar:
    image: sidecar
    network_mode: service:main-app
  main-app:
    image: main-app
```