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Configuration
Docker Connection

Docker Connection

Docker Host

Specifies the Docker daemon socket to connect to, supporting remote hosts via TCP (e.g., tcp://hostname:port).

            Argument: --host, -H
Environment Variable: DOCKER_HOST
                Type: String
             Default: unix:///var/run/docker.sock

Docker API Version

Sets the Docker API version for client-daemon communication.

            Argument: --api-version, -a
Environment Variable: DOCKER_API_VERSION
                Type: String
             Default: Autonegotiated
Falls back to autonegotiation on failure.
Refer to Docker’s API version matrix for compatibility.

Enable Docker TLS Verification

Enables TLS verification for Docker socket connections.

            Argument: --tlsverify
Environment Variable: DOCKER_TLS_VERIFY
                Type: Boolean
             Default: false

TLS Certificates Path

Path to TLS certificates for remote Docker connections.

            Argument: --cert-path
Environment Variable: DOCKER_CERT_PATH
                Type: String
             Default: None

Disable Memory Swappiness

Sets memory swappiness to nil for Podman compatibility with crun and cgroupv2, overriding Podman’s default of 0.

            Argument: --disable-memory-swappiness
Environment Variable: WATCHTOWER_DISABLE_MEMORY_SWAPPINESS
                Type: Boolean
             Default: false

CPU Copy Mode

Controls how CPU settings are copied when recreating containers, addressing Podman compatibility issues with CPU limits. Podman handles NanoCPUs differently than Docker, which can cause container recreation failures.

            Argument: --cpu-copy-mode
Environment Variable: WATCHTOWER_CPU_COPY_MODE
                Type: String
     Possible Values: auto, full, none
             Default: auto
  • auto: Automatically detects if running on Podman and filters NanoCPUs for compatibility. On Docker, copies all CPU settings.
  • full: Copies all CPU settings unchanged (original behavior).
  • none: Strips all CPU limits to avoid compatibility issues.

Use auto in mixed Docker/Podman environments. Use full if running only on Docker and want to preserve all CPU limits. Use none if CPU limits are causing issues and you prefer no limits on recreated containers.

Usage Examples

Run Watchtower with automatic CPU compatibility:

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

Force full CPU copying (Docker-only environments):

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

Strip all CPU limits:

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