The Hidden Dockerfile Mistakes That Waste Hours (Thinking of Building a Tool for This)

Source: Dev.to

Common Dockerfile Mistakes

Developers love to pretend their Dockerfiles are perfect until a build takes eight minutes and the image balloons bigger than a AAA game update. Most of the time, the cause is embarrassingly simple stuff: missing version pins, unnecessary layers, or copying half the universe into the image.

Missing version pin

RUN apt-get install python

No version pin. Enjoy the surprise upgrades later.

Copying everything indiscriminately

COPY . .

Congrats, you just shoved your entire repo and node_modules into the image because why not.

Redundant pip layers

RUN pip install --upgrade pip
RUN pip install -r requirements.txt

Two separate layers doing what one should handle.

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I’m exploring a small, focused tool that analyzes Dockerfiles and built images to catch these issues quickly. No AI circus, just rule checks and clear suggestions.

Would something like this be useful in your workflow, or do you already rely on another tool? Feel free to comment your thoughts or examples of Dockerfile mistakes you’ve faced.