require-dockerignore-file

Require .dockerignore when a repository-root Dockerfile is present.

Targeted pattern scope

Repositories that commit a root Dockerfile without a matching .dockerignore file.

What this rule reports

This rule reports repositories with a root Dockerfile that do not also commit .dockerignore.

Why this rule exists

Without .dockerignore, Docker sends the entire repository as build context. That increases build time and can accidentally include credentials, Git metadata, caches, and other files that should never reach the image build.

❌ Incorrect

FROM node:22-alpine
WORKDIR /app
COPY . .
RUN npm ci

✅ Correct

FROM node:22-alpine
WORKDIR /app
COPY . .
RUN npm ci

# .dockerignore
node_modules
.git
.env
coverage

When not to use it

Disable this rule only if the repository intentionally wants the full build context and that trade-off is understood.

Rule catalog ID: R069

Targeted pattern scope​

What this rule reports​

Why this rule exists​

❌ Incorrect​

✅ Correct​

When not to use it​

Further reading​