Retrieve Docker Run Commands & Export Dockerfiles with runlike and whaler

Docker users often need to recall the exact command used to start a container or to reconstruct the Dockerfile that built an image. Two command‑line tools, runlike and whaler , simplify these tasks.

1. Retrieve the original Docker run command with runlike

runlike

prints the full docker run command that was used to launch a given container. It can be installed via pip or run directly as a Docker container, avoiding any local installation.

# pip installation
pip install runlike

# Docker‑based usage (no install needed)
alias runlike="docker run --rm -v /var/run/docker.sock:/var/run/docker.sock assaflavie/runlike"

After setting up the alias, invoke the tool with the container name: runlike my_container_name The command outputs the complete docker run line, including all flags, environment variables, volumes, and ports, making it easy to recreate the container on another host.

2. Export a Dockerfile from an image with whaler

When the original Dockerfile is unavailable—such as for third‑party images or long‑forgotten builds— whaler can generate a best‑effort Dockerfile from the image layers. Like runlike, it can be used without installation by running a Docker container.

# Alias for convenient use
alias whaler="docker run -t --rm -v /var/run/docker.sock:/var/run/docker.sock:ro pegleg/whaler"

Run the alias with the target image name to produce the Dockerfile:

whaler pegleg/whaler

The generated Dockerfile reflects the image’s build steps, though multi‑stage builds may omit intermediate stages (e.g., the --from=builder stage). You can try different images to see more natural output.

Both tools are lightweight, require only Docker access, and help streamline container debugging and documentation workflows.