Docker tools
What the image will actually do once it is built and running.
Docker Container Image Reference Parser
Is that a registry or a Docker Hub user?
Break an image reference into registry, namespace, repository, tag and digest, fully qualified.
Dockerfile Linter
What this image will do to you later
Check a Dockerfile for what costs you later: unpinned base images, containers running as root, and credentials baked into a layer forever.
docker run to Kubernetes YAML
And the flags that have no equivalent
Turn a docker run command into a Kubernetes Deployment and Service, with the flags that have no equivalent named rather than dropped.
Docker Compose to Kubernetes
And why depends_on has no equivalent
Turn a docker-compose.yml into Kubernetes Deployments, Services and PVCs, with the parts that do not translate named rather than dropped.
Docker Logging Driver Generator
json-file never rotates
Generate Docker logging configuration with rotation, because the default json-file driver grows until the disk is full and takes the daemon with it.
Dockerfile Non-Root USER Generator
Numeric, or Kubernetes rejects it
Generate the USER, group and ownership lines a Dockerfile needs to run as a non-root user, for Debian, Alpine or distroless bases.
Docker OCI Image Labels Generator
One of them actually does something
Generate org.opencontainers.image.* labels for a Dockerfile, including the source label that links a GHCR package to its repository.
Docker Hub Pull Rate Limit Calculator
Counted per IP, not per person
Work out whether your pull volume fits Docker Hub's rate limits, and why a cached image still costs a pull.
Docker Registry Storage Calculator
Deleting a tag frees nothing
Work out what a registry actually stores. Layers are shared by digest, so fifty tags of one app cost far less than fifty images.
Docker Build Context Analyzer
All of it uploads before anything runs
Find what is making a Docker build context large. Everything in it is sent to the daemon before the first instruction, whether or not it is copied.
Docker Compose to docker run Converter
Names stop resolving
Convert a Compose file into docker run commands, including the network you have to create yourself for service names to resolve.
Docker Compose Version Migrator
version: is obsolete now
Migrate a Compose file to the Compose Specification: drop the obsolete version key, and fix links, container_name and short-form depends_on.
Docker Compose Network and Port Viewer
Everything reaches everything
See which Compose services can reach each other and which ports are published to the host, including the ones bound to every interface.
Docker Command Explainer
Which flags hand over the host
Paste a docker run command and get every flag explained, with the ones that give a container control of the host called out.
Docker BuildKit Cache Mount Generator
apt deletes the cache you just mounted
Add BuildKit cache mounts to a Dockerfile's install steps, including the two lines Debian images need before an apt cache mount does anything.
Docker BuildKit Secret Mount Generator
ARG is in docker history forever
Replace build-time ARG and ENV credentials with BuildKit secret mounts, so the value never enters a layer or the image metadata.
Docker .dockerignore Pattern Tester
*.log does not match logs/app.log
Test .dockerignore patterns against real paths. Docker uses Go's glob dialect, where a single star never crosses a slash and braces are not expanded.
Docker Image Manifest Viewer
unknown/unknown is not broken
Read a Docker or OCI image manifest: which platforms it covers, and why the unknown/unknown entries are attestations rather than faults.
Docker Image Config Viewer
Anyone who can pull can read your Env
Read an image config: the user it runs as, its environment, and why diff_ids never match the manifest's layer digests.
Docker Registry Token Decoder
Check the scope before the credentials
Decode a Docker registry bearer token and see exactly which repositories and actions it grants, without sending it anywhere.
Docker HEALTHCHECK Generator
Docker does nothing when it fails
Generate a Docker HEALTHCHECK with the time-to-unhealthy worked out, and see why plain Docker never restarts an unhealthy container.
Docker Network Subnet Calculator
31 networks, then it stops
Work out how many Docker networks the default address pools allow, and whether they collide with a VPN or corporate range.
Docker History Analyzer
The rm did not save anything
Read docker history output to find which layer added the size, and why deleting the files in a later layer made no difference.
Docker Run to Compose Converter
Some flags have no equivalent
Convert a docker run command into a Compose service, with the flags that describe the invocation rather than the service called out.
Docker CMD and ENTRYPOINT Tester
Why docker stop takes ten seconds
See what a Dockerfile's ENTRYPOINT and CMD actually run, and whether PID 1 is your process or a shell that ignores SIGTERM.
Docker Port Mapping Tester
-p reaches past your firewall
Resolve Docker -p port mappings, and find the ones published on every interface that bypass ufw and firewalld entirely.
Docker -v to --mount Converter
-v invents missing directories
Convert Docker -v mounts to --mount syntax. The difference that matters: -v creates a missing host path, --mount refuses to start.
Docker Restart Policy Simulator
The backoff resets after ten seconds
See when Docker will restart a container, how the backoff grows, and why a container that survives ten seconds never backs off at all.
Docker Exit Code Explainer
137 is two different problems
Look up a Docker container exit code. 137 is either the OOM killer or a stop timeout, and docker inspect is the only thing that tells them apart.
Docker CPU Limit Converter
--cpu-shares limits nothing
Convert between Docker --cpus, --cpu-quota and --cpu-shares, and see why a quota throttles bursty work that looks well under its limit.
Docker Memory Limit Calculator
-m 512m allows a gigabyte
Work out what a Docker memory limit actually allows. Without --memory-swap the container gets twice the limit before anything is killed.
Docker Compose Interpolation Tester
An unset variable is an empty string
Test Docker Compose ${VAR} interpolation with real .env values, including the difference between :- and - that only shows on empty values.
Docker Environment Variable Precedence Tester
Your shell does not reach the container
Work out which environment variable wins between Dockerfile ENV, env_file, environment and -e, and why your shell is not on the list.
Docker Compose Override Merge Previewer
An override can add a port, never remove one
See what docker compose -f a.yml -f b.yml produces. Some lists are appended and some are replaced, in the same merge.
Dockerfile Multi-Stage Build Analyzer
Which stages reach the image
Graph the stages in a multi-stage Dockerfile: what reaches the final image, what is dead, and which COPY --from targets do not resolve.
Dockerignore Validator
It is not .gitignore
Check a .dockerignore file: negation ordering, the leading slash that does nothing, and the entries that keep your build context small.