Inspect Any Docker Container's Original Run Command with runlike

When you inherit a server with running containers, the first question is always: how was this started? docker ps shows the image and uptime, but not the flags, environment variables, volume mounts, or network settings. docker inspect gives you everything in JSON — it’s complete but hard to read. runlike sits in the middle: it reads a container’s configuration and prints the equivalent docker run command.

Adding as an Alias

# ~/.bashrc or ~/.zshrc
alias runlike="docker run --rm -v /var/run/docker.sock:/var/run/docker.sock assaflavie/runlike"

# Now just use the container name
runlike my-web-app
runlike postgres-db
runlike redis-cache

The Problem: Container Drift

%%{ init: { 'look': 'handDrawn' } }%%
graph TD
    A[Original deployment<br/>docker run...<br/>--env VAR=value<br/>--mount /data] --> B[Container runs<br/>for 6 months]
    B --> C[Hotfix applied<br/>env changed in code]
    C --> D[Another change<br/>volume path updated]
    D --> E[Original run command<br/>completely undocumented]
    
    F[New engineer<br/>onboards] --> G[Wants to redeploy<br/>How was this started?]
    G --> H[docker ps → only image name]
    H --> I[docker inspect → JSON, hard to parse]
    I --> J[runlike → docker run command]

Without the original run command, you can’t rebuild the container with the same settings. runlike reconstructs it from the container’s stored configuration.

Using runlike

# Basic usage — pass the container name
docker run --rm -v /var/run/docker.sock:/var/run/docker.sock \
  assaflavie/runlike YOUR-CONTAINER

# Example output:
# docker run --rm \
#   --name=YOUR-CONTAINER \
#   -p 80:80 \
#   -p 443:443 \
#   -e NODE_ENV=production \
#   -v /data/app:/var/www/html \
#   --network=frontend \
#   nginx:alpine

The output is a complete docker run command that you can copy, modify, and run on any Docker host.

When This Is Essential

1. Documenting how a service was launched

# Get the run command and save it to a startup script
docker run --rm -v /var/run/docker.sock:/var/run/docker.sock \
  assaflavie/runlike nginx-proxy >> start-nginx.sh

# Make it executable
chmod +x start-nginx.sh

# Commit to the repo alongside docker-compose files
git add start-nginx.sh

2. Rebuilding after a crash

When a container fails and can’t restart (volume mount disappeared, port conflict), you need to know the exact flags to bring it back:

# Get the command, fix the issue, re-run
docker run --rm -v /var/run/docker.sock:/var/run/docker.sock \
  assaflavie/runlike broken-container

# Fix the problem (e.g., recreate volume)
docker volume create data-volume

# Re-run with corrected flags
docker run -d \
  --name=broken-container \
  -v data-volume:/data \
  -p 8080:8080 \
  my-image:tag

3. Comparing running config to docker-compose

# Get what container is actually running with
runlike running-app > actual-run.sh

# Compare to what's in docker-compose.yml
diff actual-run.sh docker-compose-derived-run.sh

Any drift between what docker-compose defines and what’s actually running becomes visible.

What runlike Reconstructs

%%{ init: { 'look': 'handDrawn' } }%%
graph LR
    A[Container config<br/>from Docker API] --> B[runlike<br/>parser]
    B --> C[docker run flags]
    C --> D[-p port mappings]
    C --> E[-e environment vars]
    C --> F[-v volume mounts]
    C --> G[--network]
    C --> H[--restart policy]
    C --> I[--user]
    C --> J[--memory limits]
    C --> K[--env-file]

runlike handles: port mappings (-p), environment variables (-e), volume mounts (-v), networks, restart policies, user/group, memory/CPU limits, and env files.

Limitations

Doesn’t capture secrets — environment variables that were set from --env-file are captured, but dynamically resolved variables (like those from a secrets manager) show as the resolved value, not the reference
Single container only — doesn’t work with Docker Swarm or Kubernetes (use kubectl get pod -o yaml for that)
Docker Socket required — the container must be accessible via the local Docker socket

For day-to-day operations, runlike is a quick bridge between “what’s running” and “how do I recreate it.”