docker-deps

docker-deps

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Extract only the essential files needed for the "install dependencies" step to optimize Docker image caching during builds, with full support for monorepos.

This project is inspired by turbo's turbo prune <subpackage> --docker command.

This package is designed for process "building Docker images using a Dockerfile", and is typically executed within CI/CD pipelines.

Features:

• Provides both CLI and JS API usage, with the latter providing TypeScript type definitions and supporting both synchronous and asynchronous methods;
• Includes many configuration options, such as dryRun, and allows configuration in package.json;
• Automatically detects .dockerignore file configurations.

CLI Usage

Run without installation:

npx -y docker-deps

After executing the command, a .docker-deps directory will be created in the root of the project, containing a minimal set of files necessary for the "install dependencies" step, such as package.json, .npmrc, yarn.lock, and others.

Step 1, Please configure the execution of this command within the CI/CD pipeline steps.

Step 2, Edit your .gitignore by appending the following line:

.docker-deps

NOTE: NEVER add this line to .dockerignore.

Step 3, Edit your .gitignore:

Before editing:

# ...

COPY . <WORKDIR>
RUN npm i
RUN npm run build

# ...

After editing:

# ...

COPY .docker-deps <WORKDIR>
RUN npm i

COPY . <WORKDIR>
RUN npm run build

# ...

The above code is used as an example, you can edit commands such as npm build as needed.

Step 4, Done!

The edited Dockerfile will first extract the minimum set of files required to install dependencies, add it to the workspace, and then install the dependencies; after the dependency installation is completed, the source code will be copied to the workspace.

When this is done, as long as the project's dependencies have not changed until the RUN npm i step, they can be cached by Docker, eliminating the time and overhead of installing dependencies in multiple builds.

If it works and you commit the code when only modifying the source code without modifying the dependencies, when building the Docker image in CI/CD, the console output should be like this:

[stage-...] RUN npm i
CACHED

The "Install dependencies" step will be completed immediately and will not take time to download and install dependencies, which indicates that the Docker Builder cache is hit.

If the location where the command is executed is different from the project directory, you can specify the CWD location:

npx docker-deps path/to/project

CLI usage also supports various parameters. For example, you can use -f or --filter to filter specific monorepo subpackage, and you can use -o or --output to customize the output directory:

npx docker-deps -o other-output-dir -f @repo/web

This will only extract the configuration files of the root package, @repo/web and other sub-packages this package depends on, and make the output directory no longer ./.docker-deps but ./other-output-dir .

For more CLI configuration option, please refer to the "Configuration Reference" chapter.

API Usage

Install this package:

npm add docker-deps # using npm
yarn add docker-deps # using yarn
pnpm add docker-deps # using pnpm

Called through JS/TS:

import { dockerDeps, dockerDepsSync } from 'docker-deps'

// Asynchronous call
dockerDeps()

// Synchronous call
dockerDepsSync()

When called through JS, it runs in the directory where process.cwd() is located.
The running directory can be customized through the cwd option:

import { dockerDepsSync } from 'docker-deps'

dockerDepsSync({
  cwd: 'path/to/project',
})

For more API configuration option, please refer to the "Configuration Reference" chapter.

Configuration Reference

Both API usage or CLI usage, this tool will read package.json located in the CWD directory and read the default configuration items from the "docker-deps" field, the format refers to "API Interface".

The configuration items in package.json have a lower priority, and the following configuration methods can override it.

In the following configuration, any relative directories that need to be provided are relative to CWD.

Options:

CLI Option	API Field	Type	Default	Introduction
-o --output	output	string	".docker-deps"	Specify output directory
-f --filter	filter	string	-	Available in monorepo, provide a package name to extract only this package and its dependencies, similar to the -F parameter of turbo prune, if not provided, all sub-packages will be extracted
-d --dry-run	dryRun	boolean	false	Only print actions to the console without actually executing them, ignore the quiet option
-q --quiet	quiet	boolean	false	Disable most console output, but will not disable output in dryRun mode
--include	include	string[]	-	Specify files to be copied additionally, using glob pattern
--exclude	exclude	string[]	-	Exclude specific files when copying, using glob pattern, separated by spaces, higher priority than include
-	configGlob	GlobOptions	-	Passed through as a configuration option for glob

When called via API, the method has a return value, which has the following fields:

• copyFiles: List of files copied by the tool, in the format Array<{ from: string; fromAbs: string; to: string; toAbs: string }>;
• configFromPackageJson: Returned as this field if the configuration was read from package.json.