Overview
Introduction
Without a .dockerignore file, `docker build` uploads your entire project folder, node_modules, the .git history, local .env files, build output, to the Docker daemon before the build even begins, which is slow and can accidentally bake secrets or bloat into an image layer.
This tool generates a .dockerignore tailored to your stack, combining sensible defaults every project needs with the dependency and build-output directories specific to Node, Python, PHP, Java, Laravel, React, or Next.js.
What Is .dockerignore Generator?
A .dockerignore file generator covering seven stack presets, each combining a common baseline (.git, .env files, editor folders, logs) with that stack's typical dependency and build-artifact directories.
You can also add custom entries on top of any preset, for example an extra local data directory or a stack-specific cache folder the preset doesn't already cover.
How .dockerignore Generator Works
Choosing a stack preset merges a fixed list of common entries (like .git, .env, .env.*, *.log) with that stack's specific entries (node_modules/ for Node/React/Next.js, __pycache__/ and .venv/ for Python, vendor/ for PHP/Laravel, target/ for Java).
Any custom entries you type are appended and the combined list is deduplicated, so entries already covered by the preset don't appear twice even if you re-type them.
When To Use .dockerignore Generator
Use it any time you're writing a new Dockerfile for a project that doesn't have a .dockerignore yet, since the file is easy to forget until a build is unexpectedly slow or an image is unexpectedly large.
It's also useful when a build context suddenly grows, to double-check you're excluding the right build-output and dependency folders for your specific stack.
Often used alongside Dockerfile Generator and Multi-Stage Docker Builder.
Features
Advantages
- Bundles the common entries every project should exclude with stack-specific ones, so nothing obvious gets missed.
- Deduplicates automatically when custom entries overlap with preset entries.
- Covers seven common stacks including framework-specific ones like Laravel and Next.js with their particular cache/build directories.
Limitations
- Presets are a reasonable starting point, not a guarantee, review the output against your actual project layout before relying on it.
- Doesn't inspect your actual project files, so it can't detect stack-specific quirks like an unusual build output directory.
- Only supports one stack preset at a time; for a monorepo mixing stacks, generate each preset separately and merge the results.
Examples
Best Practices & Notes
Best Practices
- Always exclude .env and .env.* even if you also exclude them in .gitignore, since .dockerignore governs the build context independently.
- Exclude your dependency directory (node_modules/, vendor/, .venv/) so Docker installs fresh inside the image rather than copying a possibly incompatible host-installed copy.
- Re-check the generated list whenever you add a new build tool or cache directory to the project.
Developer Notes
The generator merges three string arrays in order (a fixed COMMON_ENTRIES list, the preset's stack-specific list, then user-supplied custom entries) using a Set to drop exact-string duplicates while preserving first-seen order, so a custom entry that exactly matches a preset entry doesn't produce a repeated line. It performs no glob validation, since .dockerignore patterns are intentionally permissive and validating them meaningfully would require re-implementing Docker's own pattern matcher.
.dockerignore Generator Use Cases
- Adding a missing .dockerignore to an existing project before its first Docker build
- Making sure local secrets in .env files never end up inside an image layer
- Speeding up docker build by shrinking the context sent to the daemon on large projects
Common Mistakes
- Assuming .gitignore already covers this, .dockerignore is a separate file the Docker CLI reads independently and isn't inferred from git.
- Forgetting to exclude the local dependency folder (node_modules/, vendor/, .venv/), which bloats the build context and can introduce host/container inconsistencies.
- Not excluding .env files, risking a stray COPY . . step baking local secrets into an image layer.
Tips
- Pair this with the Dockerfile Generator or Multi-Stage Docker Builder, both assume a COPY . . step that this .dockerignore keeps lean.
- If you're unsure what's bloating your build context, run `docker build` once without a .dockerignore and note the 'Sending build context' size Docker reports, then compare after adding this file.