isolate-package

Isolate Package

Isolate a monorepo workspace package so that it can be deployed as a completely self-contained directory with the sources of all its local dependencies included.

Motivation

This solution was developed out of a desire to deploy to Firebase from a monorepo without resorting to hacks, shell scripts and manual tasks. I have written an article explaining the issue here.

There is nothing Firebase specific to this solution but I am currently not aware of other reasons to isolate a workspace package. If you find a different use-case, I would love to hear about it.

In the documentation and code you will see the word "manifest" a lot, and it simply means to the contents of a package.json file.

Features

• Zero-config for the vast majority of use-cases, with no manual steps involved.
• Support NPM, Yarn classic (v1) and current (v3) and PNPM.
• Fully compatible with the Firebase tools CLI, supporting 1st gen and 2nd gen Firebase functions.
• Uses a pack/unpack approach to isolate only the files that would have been part of a published package, so the output contains a minimal set of files.
• Isolates shared dependencies recursively. If package A depends on local package B which depends on local package C, all of them will be isolated.
• Includes the lockfile so the isolated deployment should be deterministic. PNPM lockfiles are not supported yet. See lockfiles for more info.
• Optionally include devDependencies in the isolated output.

Firebase Deployment Quickstart

This describes the steps required for Firebase deployment, assuming:

• You use a fairly typical monorepo setup
• Your firebase.json config lives in the root of the package that you like to deploy to Firebase, hereafter referred to as the "target package".

If you use a different setup, just continue reading the Prerequisites section.

1. In the target package, install isolate-package and firebase-tools by running pnpm add isolate-package firebase-tools -D or the Yarn / NPM equivalent. I like to install firebase-tools as a devDependency in every firebase package, but you could of course also use a global install if you prefer.
2. In the firebase.json config set "source" to "./isolate" and "predeploy" to ["turbo build", "isolate"] or whatever suits your build tool.
3. From the target package root, you should now be able to deploy with npx firebase deploy or npx firebase deploy --only functions in case your package only contains code for Firebase functions.

I recommend keeping a firebase.json file inside each Firebase package (as opposed to the monorepo root), because it allows you to deploy from multiple independent packages. This give you more flexibility to organize your code. It also makes it easy to deploy 1st gen functions next to 2nd gen functions, or mix different node versions should you want to. Your bundle sizes and dependency lists for each function might also decrease, which improves cold-start times.

Prerequisites

Because historically many different approaches to monorepos exist, we need to establish some basic rules for the isolate process to work.

Define shared package dependencies in the manifest

This one might sound obvious, but if the package.json from the package you are targeting does not list the other monorepo packages it depends on, in either the dependencies or devDependencies list, then the isolate process will not include them in the output.

How dependencies are listed with regards to versioning is not important, because packages are matched based on their name. For example the following flavors all work:

// package.json
{
  "dependencies": {
    "shared-package": "workspace:*",
    "shared-package": "*",
    "shared-package": "../shared-package",
    "shared-package": "^1.0.0"
  }
}

So basically, version information is ignored, and if the package name can be found in the list of local monorepo packages, it will be processed regardless of its version specifier.

Define "files" and "version" in each manifest

The isolate process uses (p)npm pack to extract files from package directories, just like publishing a package would.

For this to work it is required that you define the files property in each package.json manifest, as it declares what files should be included in the published output.

Typically the value contains an array with just the name of the build output directory, for example:

// package.json
{
  "files": ["dist"]
}

The version field is also required for pack to execute. I personally always set it to "0.0.0" to indicate that the version does not have a practical function.

A few additional files will be included by pack automatically, like the package.json and README.md files.

Tip If you deploy to Firebase 2nd generation functions, you might want to include some .env files in the "files" list, so they are packaged and deployed together with your build output (as 1st gen functions config is no longer supported).

Use a flat structure inside your packages folders

At the moment, nesting packages inside packages is not supported.

When building the registry of all local packages, isolate doesn't drill down into the folders. So if you declare your packages to live in packages/* it will only find the packages directly in that folder and not at packages/nested/more-packages.

You can, however, declare multiple packages folders like ["packages/*", "apps/*"]. It's just that the structure inside them should be flat.

Usage

Run npm install isolate-package --dev or the equivalent for yarn or pnpm.

This package exposes the isolate executable. Once installed you can run npx isolate in any package directory after you have build the source files. By default this will produce a directory at ./isolate but this can be configured.

You will probably want to add the output directory to your .gitignore file.

Deploying to Firebase

You can deploy to Firebase from multiple packages in your monorepo, so I advise you to co-locate your firebase.json file with the source code, and not place it in the root of the monorepo. If you do want to keep the firebase config in the root, some additional configuration is required, so read on.

In order to deploy to Firebase, the functions.source setting in firebase.json needs to point to the isolated output folder, which would be ./isolate when using the default configuration.

The predeploy phase should first build and then isolate the output.

Here's an example using Turborepo:

// firebase.json
{
  "functions": {
    "source": "./isolate",
    "predeploy": ["turbo build", "isolate"]
  }
}

With this configuration you can then run firebase deploy --only functions from the package.

If you like to deploy to Firebase Functions from multiple packages you will also need to configure a unique codebase identifier for each of them. For more information, read this.

Make sure your Firebase package adheres to the things mentioned in prerequisites and its manifest file contains the field "main", or "module" if you set "type": "module", so Firebase knows the entry point to your source code.

Deploying to Firebase from the root

If, for some reason, you choose to keep the firebase.json file in the root of the monorepo you will have to place a configuration file called isolate.config.json in the root with the following content:

// isolate.config.json
{
  "targetPackagePath": "./packages/your-firebase-package"
}

The Firebase configuration should then look something like this:

// firebase.json
{
  "functions": {
    "source": "./packages/your-firebase-package/isolate",
    "predeploy": ["turbo build", "isolate"]
  }
}

Configuration Options

For most users no configuration should be required. You can configure the isolate process by placing a isolate.config.json file in the package that you want to isolate, except when you're deploying to Firebase from the root of the workspace.

For the config file to be picked up, you will have to execute isolate from the same location, as it uses the current working directory.

Below you will find a description of every available option.

buildDirName

Type: string | undefined, default: undefined

The name of the build output directory name. When undefined it is automatically detected via tsconfig.json. When you are not using Typescript you can use this setting to specify where the build output files are located.

excludeLockfile

Type: boolean, default: Depends on package manager.

Sets the inclusion or exclusion of the lockfile as part of the deployment. For Yarn and NPM the lockfiles are included by default, but for PNPM they are excluded by default because they are not supported yet. For more information see lockfiles.

includeDevDependencies

Type: boolean, default: false

By default devDependencies are ignored and stripped from the isolated output package.json files. If you enable this the devDependencies will be included and isolated just like the production dependencies.

isolateDirName

Type: string, default: "isolate"

The name of the isolate output directory.

logLevel

Type: "info" | "debug" | "warn" | "error", default: "info".

Because the configuration loader depends on this setting, its output is not affected by this setting. If you want to debug the configuration set ISOLATE_CONFIG_LOG_LEVEL=debug before you run isolate

targetPackagePath

Type: string, default: undefined

Only when you decide to place the isolate configuration in the root of the monorepo, you use this setting to point it to the target you want to isolate, e.g. ./packages/my-firebase-package.

If this option is used the workspaceRoot setting will be ignored and assumed to be the current working directory.

tsconfigPath

Type: string, default: "./tsconfig.json"

The path to the tsconfig.json file relative to the package you want to isolate. The tsconfig is only used for reading the compilerOptions.outDir setting. If no tsconfig is found, possibly because you are not using Typescript in your project, the process will fall back to the buildDirName setting.

workspacePackages

Type: string[] | undefined, default: undefined

When workspacePackages is not defined, isolate will try to find the packages in the workspace by looking up the settings in pnpm-workspace.yaml or package.json files depending on the detected package manager.

In case this fails, you can override this process by specifying globs manually. For example "workspacePackages": ["packages/*", "apps/*"]. Paths are relative from the root of the workspace.

workspaceRoot

Type: string, default: "../.."

The relative path to the root of the workspace / monorepo. In a typical repository you will have a packages and possibly an apps directory, and both contain packages, so any package you would want to isolate is located 2 levels up from the root.

For example

apps
├─ api
│  ├─ package.json
│  └─ .eslintrc.js
└─ web
   ├─ package.json
   └─ .eslintrc.js
packages
└─ eslint-config-custom
   ├─ index.js
   └─ package.json

When you use the targetPackagePath option, this setting will be ignored.

Troubleshooting

If something is not working, I advise you to add a isolate.config.json file, and set "logLevel" to "debug". This should give you detailed feedback in the console.

In addition define an environment variable to debug the configuration being used by setting ISOLATE_CONFIG_LOG_LEVEL=debug before you execute isolate

When debugging Firebase deployment issues it might be convenient to trigger the isolate process manually with npx isolate and possibly ISOLATE_CONFIG_LOG_LEVEL=debug npx isolate

Lockfiles

The lockfiles for NPM as well as the Yarn v1 and v3 seem to have a flat structure unrelated to the workspace packages structure, so they are copied to the isolate output as-is.

The PNPM lockfile clearly has a structure describing the different packages by their relative paths, and so to correct the lockfile it is adapted before being stored to the isolate directory.

NPM

It seems that when using NPM the npm ci can fail with a message like:

npm ci can only install packages when your package.json and package-lock.json or npm-shrinkwrap.json are in sync. Please update your lock file with npm install before continuing.

I haven't been able to figure out what causes this. I have seen NPM deploys working with lockfiles, but I can not reliably reproduce it.

If you experience this issue I have two suggestions:

• Upgrade to Node 18 by setting the "runtime": "nodejs18" in your firebase.json config. Note that you most likely also have to re-create your lockfile using Node 18.
• Exclude the lockfile from deployment by setting "excludeLockfile": false in your isolate.config.json file.

I hope we can eventually figure out what is causing this, but more investigation is required.

PNPM Lockfiles disabled for now

There is still an issue with the PNPM lockfile conversion which makes it unusable at the moment. Until that is resolved, the lockfile is automatically excluded for PNPM.

Personally I also use PNPM, and I don't see this as a big problem, because, like most of us, I declare versions with ^ in my manifest. This means that dependencies can only resolve to newer patch versions, but I am not using dependencies that are likely to break on patch version changes.

Different Package Managers

Isolate package has been designed to work with all package managers. It has been testing it with NPM 8, 9, Yarn 1.22, Yarn 3.6 and PNPM 8.

The isolate process will infer the package manager name and version from the type of lockfile found and the version that the OS reports for the installed executable. This information is then used to change some of its behavior. For example, the PNPM pack process is preferred over the default NPM pack if PNPM in used, simply because it seems to be much faster.

The Firebase cloud deploy pipeline will use the package manager that matches lockfile that was found in the deployed package.

Yarn v1 and v3

If you are using Yarn 3 with zero-installs, the deployed package is not aware of that, because the .yarnrc file and .yarn folder are located in the root of your monorepo, and the version is not recorded as part of the lockfile. Therefor the Firebase deploy cloud pipeline will use Yarn 1 to install your dependencies. I don't think that is an issue but it might be good to know.