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Dockerfile リンター

Dockerfile のベストプラクティス、セキュリティ上の問題、最適化ポイントを解析します。

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Dockerfile Content

2 errors 10 warnings 3 info

Line 1DL3007ERROR

Using `latest` tag in FROM (image: ubuntu:latest)

Pin a specific version tag, e.g. ubuntu:22.04 instead of ubuntu:latest.

Line 8DL3020ERROR

ADD used where COPY would suffice

Use COPY instead of ADD for copying local files. ADD has extra features (auto-extract, remote URLs) that can be surprising.

Line 2DL4000WARNING

MAINTAINER is deprecated

Use LABEL maintainer="name@example.com" instead.

Line 5DL3015WARNING

Using `apt-get install` without `--no-install-recommends`

Add --no-install-recommends to avoid installing unnecessary packages and reduce image size.

Line 6DL3014WARNING

Using `apt-get install` without `-y` flag

Add -y flag to avoid interactive prompts: apt-get install -y.

Line 6DL3015WARNING

Using `apt-get install` without `--no-install-recommends`

Add --no-install-recommends to avoid installing unnecessary packages and reduce image size.

Line 6DL3009WARNING

Missing `apt-get clean` or `rm -rf /var/lib/apt/lists/*` after install

Clean up apt cache in the same RUN layer to reduce image size.

Line 11DL3004WARNING

Using `sudo` in Dockerfile

Avoid sudo. Use USER to switch users, or run commands as root directly (default in Docker).

Line 13DL3011WARNING

EXPOSE with no port number

Specify a valid port number, e.g. EXPOSE 8080.

Line 15DL3006WARNING

Missing HEALTHCHECK instruction

Add a HEALTHCHECK to let Docker know how to check that the container is still working.

Line 15DL3002WARNING

Running as root — no USER instruction found

Add a USER instruction to run the container as a non-root user for better security.

Line 15DL3025WARNING

CMD uses shell form instead of exec form

Use exec form: CMD ["executable", "arg1", "arg2"] for proper signal handling.

Line 1DL3005INFO

Consider using a .dockerignore file

A .dockerignore file helps exclude unnecessary files from the build context, speeding up builds and reducing image size.

Line 4DL3003INFO

4 consecutive RUN instructions found

Combine RUN instructions using && to reduce image layers.

Line 9DL3000INFO

WORKDIR should use an absolute path

Use an absolute path, e.g. WORKDIR /app instead of WORKDIR app.

What is Dockerfile リンター?

Dockerfile リンター helps people convert, inspect, validate, or generate dockerfile, docker, lint, linter, best practices, container directly in the browser. It is designed for everyday work, coding, debugging, documentation, quality checks, and data preparation where clear input, reliable output, and privacy-first local processing matter.

Dockerfile リンターの使い方

1対象の文字列、ヘッダー、トークン、設定、証明書などを入力欄へ貼り付けるか読み込みます。
2必要なモードや判定条件を選び、解析結果や警告を表示します。
3展開されたフィールド、検証結果、注意点を確認し、必要ならコピーして共有します。

Common Dockerfile リンター use cases

Developer debugging

Use Dockerfile リンター to quickly inspect generated output, API payloads, configuration values, or encoded data while building and debugging software.

Review before reuse

Validate or transform dockerfile, docker, lint, linter, best practices, container before adding the result to a project, document, form, message, or shared file.

Privacy-first browser processing

Run common dockerfile, docker, lint, linter, best practices, container tasks locally in the browser without sending sensitive development data to a backend service.

よくある質問

What problem does Dockerfile リンター solve?

Dockerfile のベストプラクティス、セキュリティ上の問題、最適化ポイントを解析します。

Do I need to install software to use Dockerfile リンター?

No. The tool works in a modern web browser, so you can complete the task without installing a separate desktop application.

Does this tool upload my data?

The tool is designed to run in the browser whenever possible. Tools that require a backend or AI service are labeled separately.

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