How do I install the Dockerignore Generation skill?

Run npx skillmds@latest add nixopus/dockerignore-generation in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

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Is Dockerignore Generation free to use?

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Who published Dockerignore Generation?

nixopus (@nixopus) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Dockerignore Generation by nixopus — Agent Skill

Name: Dockerignore Generation
Author: nixopus

Dockerignore Generation

Generate ecosystem-specific .dockerignore files to reduce build context size and prevent secret leaks. Use when no .dockerignore exists, when the build context is large, or when secrets may be leaking into images.

nixopus 6216e74 2.8 KB Updated Sep 17, 2026

File contents

.dockerignore Generation

Why It Matters

Without a .dockerignore:

Build context includes node_modules (hundreds of MB), .git history, and local env files
Secrets in .env files get copied into the image and are extractable
Build is slow because Docker sends the entire directory to the daemon

Base Template (all ecosystems)

Every .dockerignore should include:

.git
.gitignore
.env
.env.*
!.env.example
!.env.sample
*.md
!README.md
LICENSE
docker-compose*.yml
.dockerignore
Dockerfile
.vscode
.idea
.cursor

Ecosystem-Specific Entries

Node.js

node_modules
.next
.nuxt
.output
dist
build
.cache
coverage
.nyc_output
*.log
npm-debug.log*
yarn-debug.log*
yarn-error.log*
.pnpm-debug.log*
.turbo
.vercel
.netlify
storybook-static

Python

__pycache__
*.pyc
*.pyo
*.egg-info
.eggs
.venv
venv
env
.tox
.pytest_cache
.mypy_cache
.ruff_cache
htmlcov
*.cover

Go

vendor/
*.test
*.out
bin/
tmp/

Rust

target/
*.rs.bk

Java

target/
build/
.gradle/
*.class
*.jar
!*.jar  # if copying JARs intentionally, remove this line
.settings/
.classpath
.project

Ruby

vendor/bundle
.bundle
log/
tmp/
coverage/
spec/reports

PHP

vendor/
storage/logs/
storage/framework/cache/
storage/framework/sessions/
storage/framework/views/
bootstrap/cache/

Elixir

_build/
deps/
.elixir_ls/
cover/

.NET

bin/
obj/
*.user
*.suo
packages/

Generation Logic

Start with the base template
Detect ecosystem from the project (check for package.json, go.mod, requirements.txt, etc.)
Append the matching ecosystem entries
If test/ or tests/ or __tests__/ exists: add test directories
If .github/ exists: add .github/
Write to .dockerignore at the project root

Gotchas

!.env.example negates the .env.* exclusion — keep example env files so Dockerfile can reference them
Monorepos: .dockerignore is relative to the build context root, not the Dockerfile location
Docker Compose build.context changes what .dockerignore applies to — if context is ., the root .dockerignore applies
Don't ignore prisma/ if Prisma is used — prisma/schema.prisma is needed for postinstall
Don't ignore lockfiles (package-lock.json, yarn.lock, etc.) — they're essential for reproducible builds

Related Skills

pre-deploy-checklist — Checks for .dockerignore existence and flags missing ones
dockerfile-generation — Generate .dockerignore alongside the Dockerfile

---name: dockerignore-generationdescription: Generate ecosystem-specific .dockerignore files to reduce build context size and prevent secret leaks. Use when no .dockerignore exists, when the build context is large, or when secrets may be leaking into images.---# .dockerignore Generation## Why It MattersWithout a `.dockerignore`:- Build context includes `node_modules` (hundreds of MB), `.git` history, and local env files- Secrets in `.env` files get copied into the image and are extractable- Build is slow because Docker sends the entire directory to the daemon## Base Template (all ecosystems)Every `.dockerignore` should include:```.git.gitignore.env.env.*!.env.example!.env.sample*.md!README.mdLICENSEdocker-compose*.yml.dockerignoreDockerfile.vscode.idea.cursor```## Ecosystem-Specific Entries### Node.js```node_modules.next.nuxt.outputdistbuild.cachecoverage.nyc_output*.lognpm-debug.log*yarn-debug.log*yarn-error.log*.pnpm-debug.log*.turbo.vercel.netlifystorybook-static```### Python```__pycache__*.pyc*.pyo*.egg-info.eggs.venvvenvenv.tox.pytest_cache.mypy_cache.ruff_cachehtmlcov*.cover```### Go```vendor/*.test*.outbin/tmp/```### Rust```target/*.rs.bk```### Java```target/build/.gradle/*.class*.jar!*.jar # if copying JARs intentionally, remove this line.settings/.classpath.project```### Ruby```vendor/bundle.bundlelog/tmp/coverage/spec/reports```### PHP```vendor/storage/logs/storage/framework/cache/storage/framework/sessions/storage/framework/views/bootstrap/cache/```### Elixir```_build/deps/.elixir_ls/cover/```### .NET```bin/obj/*.user*.suopackages/```## Generation Logic1. Start with the base template2. Detect ecosystem from the project (check for `package.json`, `go.mod`, `requirements.txt`, etc.)3. Append the matching ecosystem entries4. If `test/` or `tests/` or `__tests__/` exists: add test directories5. If `.github/` exists: add `.github/`6. Write to `.dockerignore` at the project root## Gotchas- `!.env.example` negates the `.env.*` exclusion — keep example env files so Dockerfile can reference them- Monorepos: `.dockerignore` is relative to the build context root, not the Dockerfile location- Docker Compose `build.context` changes what `.dockerignore` applies to — if context is `.`, the root `.dockerignore` applies- Don't ignore `prisma/` if Prisma is used — `prisma/schema.prisma` is needed for `postinstall`- Don't ignore lockfiles (`package-lock.json`, `yarn.lock`, etc.) — they're essential for reproducible builds## Related Skills- **`pre-deploy-checklist`** — Checks for `.dockerignore` existence and flags missing ones- **`dockerfile-generation`** — Generate `.dockerignore` alongside the Dockerfile

Frequently asked questions