70 Docker Container Jokes Only DevOps Engineers Will Get

"It works on my machine." "Then we will ship your machine." And that is how Docker was invented.

My Dockerfile is 14 lines. My image is 2.7 gigabytes. These numbers feel disproportionate.

"Just use Alpine." Three hours later: missing libc, missing curl, missing the will to live.

The first rule of Docker: It works locally. The second rule of Docker: It does not work in CI.

Every Dockerfile I have ever written starts with a comment that says "TODO: optimize layers" and stays that way for three years.

"Why is the build slow?" Because you invalidated the cache by editing the COPY line.

Docker Hub rate limits are how I learned that anonymous pulls are a luxury, not a right.

I asked the junior to dockerize the app. He added FROM ubuntu:latest at the top and called it a day.

A `docker ps` returns nothing. A `docker ps -a` returns 47 containers. None of them are mine, apparently.

"Why is my container exiting immediately?" Because your CMD ran and finished. That is the whole job of a CMD.

Building from a Dockerfile is fine. Understanding someone else's Dockerfile is archaeology.

There are two kinds of people: Those who pin image versions, and those who learned to the hard way.

"latest" is not a version. It is a promise from someone who has already moved on.

Multi-stage builds saved my image size. They also turned my Dockerfile into a screenplay.

I ran `docker system prune -a`. The build cache I had been nurturing for months is gone. The disk is happy. I am not.

Bind mounts on macOS are slow because the universe is fair.

"Just rebuild the image." Sure. I have forty minutes.

Every `docker run` command in production was assembled from three different blog posts and one Slack message.

Docker Compose is what we use until we say the word Kubernetes out loud at a meeting.

"The container is running." "The app inside the container is not." "Yes, but the container is running."

I added a HEALTHCHECK to the Dockerfile. Now my container restarts every 30 seconds and I have no idea why.

There is a special place in production for the engineer who runs containers as root.

Container networking is straightforward once you accept that nothing is straightforward about container networking.

"Why is the volume empty?" Because you mounted a host directory over the one that had data in it. That is just how mounts work.

I have a Dockerfile that has not been edited in four years. It is the only thing in our infrastructure that has never gone down.

Three engineers, three machines, three different results from the same `docker build`. This is what BuildKit was invented to fix and somehow has not.

Docker security scan results: 247 known vulnerabilities. Fix: pin to a different image with 248 known vulnerabilities.

The Dockerfile says `FROM node:18`. The lockfile expects 20. The build passes. The runtime does not.

"Just exec into the container and check." The container is `distroless` and does not have a shell. Good luck.

Every production incident eventually leads back to someone using `:latest` somewhere.

I tried to write a small image. It is 180 megabytes. I checked the size of a Hello World binary in Go. It is 6 megabytes. I hate everything.

"The container is on the host network." Then it is not really a container, friend.

Docker Desktop wants to update. Docker Desktop always wants to update. The update will break my volumes. I know this. I click later.

Layer caching is a beautiful idea. Layer caching that respects your COPY order is a unicorn.

"Use a .dockerignore file." The one nobody adds until their image hits 5 gigabytes.

I built a container that runs Postgres, Redis, the app, the worker, and the cron job. It also runs nothing for very long.

ENTRYPOINT versus CMD is a thirty-minute conversation that resolves to "use both and hope."

"Why is the timezone wrong inside the container?" Because containers have no concept of where you live until you mount /etc/localtime.

Docker on ARM. Docker on x86. Same image. Different behavior. Welcome to multi-arch.

I once spent four hours debugging a permissions issue that turned out to be a UID mismatch on a bind mount. That is an entire afternoon I will never get back.

"Run the container in detached mode." Great. Now I have no idea what it is doing and no logs.

`docker logs` is the only debugging tool I have. It is also the only one I trust.

The image is small. The app inside the image is broken. We call this engineering progress.

A `RUN apt-get update` without `&& apt-get install` is a layer of pure waste. Nobody told me that for two years.

Every Dockerfile has one line that nobody on the team can explain and nobody is brave enough to delete.

"Why is the image so big?" Because you copied node_modules in before running `npm ci`.

Docker Compose worked until it didn't, and now the YAML file is 400 lines and somehow still missing a service.

I read "containers are lightweight" once in 2014 and have been disappointed ever since.

"The container has its own filesystem." Yes, and you just wiped it because you restarted without a volume.

There are two ways to debug a Docker network issue: Give up, or read the source of libnetwork. Both are valid.

The container starts in 200 milliseconds. The app inside takes 90 seconds to be ready. Guess which one the orchestrator believes.

"Use a sidecar." Now I have two containers that do not work instead of one.

I keep a `Dockerfile.dev` and a `Dockerfile.prod`. They have drifted so far apart they no longer know each other.

"Mount the Docker socket into the container." That is also known as: "give the container root on the host." Just so we are clear.

Every team has a `base-image` repo that nobody owns and everyone depends on.

I tried `docker-compose up` on a Monday morning. It is now Wednesday and I am still rebuilding images.

"Why does the image work on staging but not prod?" Because prod uses a different registry and you forgot to push the new tag.

I labeled my image with a git SHA. I deployed an image with a different git SHA. Nobody can explain this.

The fastest way to find out what is inside a container is to wait for it to crash and read the logs.

"Stateless containers." My container has a file in /tmp that the whole business depends on.

Pulling an image over hotel Wi-Fi is a spiritual exercise.

Docker volumes outlive the company that created the container that wrote them.

"Use docker init." It generated a Dockerfile that does not work for my app. Useful.

The container restarts. The container restarts. The container restarts. Kubernetes calls this self-healing. I call it denial.

I run the same `docker build` command twice in a row. Different output. No code changed. This is where my faith in determinism ended.

A container is just a process with delusions of isolation.

"Use a non-root user inside the container." The app no longer has permission to write to the volume it needs. Wonderful.

Docker Hub deprecated the image I built my whole stack on. This is what they call a learning opportunity.

I have a folder full of half-finished Dockerfiles named `Dockerfile`, `Dockerfile.bak`, `Dockerfile.old`, and `Dockerfile.final.actually-final`.

The thing nobody tells you about Docker is that the hard part is not building the image. The hard part is convincing other people to use yours instead of writing their own.