Dockerfile Generator
Assemble a clear single-stage Dockerfile from explicit build and runtime commands.
Draft a predictable container build
A Dockerfile is easiest to audit when every build decision is visible. This generator creates a single-stage file from a user-supplied base image, work directory, dependency-file pattern, install command, source copy, optional build command, exposed port, and start command. The start command is shell-tokenized and emitted in JSON exec form so signal handling is clearer than a shell-form CMD.
The defaults create a Node Alpine image, work in /app, copy package manifests before npm ci for dependency-layer caching, copy the source, run the build, expose port 3000, and start with a JSON array containing npm and start. Every command must remain on one line, and the port is validated from 1 through 65535.
Layer caching and production review
The result is a starting Dockerfile, not a claim that one image or command fits every project. Production containers may need multi-stage builds, a non-root user, health checks, pinned digests, native build packages, or a smaller runtime stage. Generation happens in your browser without reading local files. Review the build context and create a suitable .dockerignore before building the image.
Frequently Asked Questions
Why is the dependency file copied before the full source?
That ordering lets Docker reuse the dependency-install layer when application code changes but dependency manifests do not.
Why does CMD use JSON array form?
Exec form avoids an extra shell and generally forwards container signals more directly to the process.
Does this produce a multi-stage Dockerfile?
No. It creates a clear single-stage draft; add separate build and runtime stages when your project benefits from them.
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