marp	theme	size	auto-scaling	title
true	gaia	58140	code	Monorepos

Monorepos

Agenda

Lerna
What does a monorepo look like?
Lerna Commands
Lerna with NPM
Lerna with Yarn
Yarn Workspaces
Lerna with Yarn Workspaces
GitHub Packages

Lerna

Splitting up large codebases into separate independently versioned packages is useful for code sharing.
Tracking changes and testing accross repositories becomes difficult very quickly.
Organize your codebases into multi-package repositories also known as monorepos.
Examples: Angular, Jest, React...
Lerna helps you optimize to manage multi-package repositories !

What does a monorepo look like?

./my-monorepo
│
│  README.md
│  package.json
│
-───packages
    │
    -────package-1
    │   │  README.md
    │   │  package.json
    │   │   ...
    -────package-2
    │   │  README.md
    │   │  package.json
    │   │   ...
    -────package-3
        │  README.md
        │  package.json
        │   ...

Lerna Commands

lerna init
lerna bootstrap
lerna run
lerna exec
lerna add
lerna version
lerna publish
lerna clean
lerna info

Lerna init

Install Lerna for access to the CLI. Creates a new Lerna repo or upgrades an existing repo to the current version of Lerna

$ lerna init

Lerna will be added as a devDependency in package.json.
Creates a lerna.json config file to store the version number.
By default Lerna projects operate on a single line version. The version is kept in the lerna.json file at the root of your project under the version key.
Independent mode allows you to increment package versions independently of each other. Each time you publish, you will get a prompt for each package that has changed to specify if it's a patch, minor or major change.
```
# Independent mode
$ lerna init --independent
```

Lerna bootstrap

Bootstraps the packages in the current repo.

$ lerna bootstrap

Installs all of the dependencies and links any cross-dependencies. It will symlink together all packages that are dependencies of each other.
Runs the prepublish and prepare scripts in all bootstrapped packages.
The prepublish script is deprecated and has been replaced with the prepare script. The NPM CLI runs the prepublish script for both npm publish and npm install.
Use prepublishOnly script to only run a script before npm publish.
Use the --hoist flag to install dependencies at the repo root. Binaries from these dependencies are linked into the dependent package node_modules/.bin directory.
```
$ lerna bootstrap [glob]
```

Lerna run

Run a script in each package that contains that script.

$ lerna run <script> -- [..args]

For example, running the unit tests for each package.
```
$ lerna run test
```
Stream the output from the child processes immediately, prefixed with the package name.
```
$ lerna run test --stream
```
Can also be run in parallel.
```
$ lerna run test --stream --parallel
```

Lerna exec

Run a command in each package.

$ lerna exec -- <command> [...args]

For example, for cleaning each package folder.

$ lerna exec -- rm -rf ./coverage ./dist ./node_modules junit.xml

Scoped packages are supported.

$ lerna exec --scope @geersch/logging -- rm -rf  ./node_modules

Can also be run in parallel.

$ lerna exec --parallel -- rm -rf  ./node_modules

Lerna add

Add a package as a dependency to packages in the current repo.

$ lerna add <package>[@version] [--dev] [--exact] [--peer]

For example:

$ lerna add lodash
$ lerna add lodash --scope @geersch/logging

Adding a development dependency.

$ lerna add debug --dev
$ lerna add debug --dev --scope @geersch/logging

Adding a peer dependency.

$ lerna add lodash --peer
$ lerna add lodash --peer --scope @geersch/logging

Lerna version

Identifies the packages that have been updated and will prompt for a new version.

$ lerna version

By default it commits the changes, tags the commit and pushes to the remote.

Use --no-git-tag-version if you don't want it to create a commit.
```
$ lerna version --no-git-tag-version
```

You can also pass a semver level and the --yes flag to skip the selection prompt

$ lerna version [major | minor | patch | premajor | preminor | prepatch | ...] --yes

If you use the --conventional-commits flag, then it will use the Conventional Commits specification to determine the version bump and generate CHANGELOG.md files.
```
$ lerna version --conventional-commits
```

Lerna publish

Identifies the packages have been updated and publishes them.

$ lerna publish

Calls lerna version and publishes the packages updated since the last release.

Use from-git to publish packages tagged in the current commit.
```
$ lerna publish from-git
```
Use from-package to inspect each package.json file and publish if the package version is not present in the registry. Handy if a previous lerna publish failed to publish all the packages.
```
$ lerna publish from-package
```

Lerna clean

Remove the node_modules directory from all packages.

$ lerna clean

I prefer lerna exec to clean each package folder.

Just put the following purge script in the package.json file at the root of your project.
```
{
  "purge": "lerna exec --parallel -- rm -rf ./node_modules ./coverage ./dist junit.xml"
}
```

Or use lerna run and provide a script per package.

$ lerna run clean
$ lerna run --scope @geersch/logging clean

Lerna info

Prints local environment information that can be useful for submitting bug reports.

$ lerna info

Environment info:

System:
  OS: macOS 10.15.6
  CPU: (12) x64 Intel(R) Core(TM) i7-8750H CPU @ 2.20GHz
Binaries:
  Node: 12.16.1 - ~/.nvm/versions/node/v12.16.1/bin/node
  Yarn: 1.22.5 - ~/.nvm/versions/node/v12.16.1/bin/yarn
  npm: 6.14.8 - ~/.nvm/versions/node/v12.16.1/bin/npm
Utilities:
  Git: 2.24.3 - /usr/bin/git
npmPackages:
  lerna: ^3.22.1 => 3.22.1

Lerna with NPM

git clone https://github.com/geersch/lerna.git

git checkout master

Lerna with NPM

Installation

By default Lerna uses NPM as the client to run commands with.

$ mkdir lerna
$ cd lerna
$ npx lerna init
$ npm install

lerna.json

{
  "packages": [
    "packages/*"
  ],
  "version": "independent",
  "command": {
    "publish": {
      "registry": "https://npm.pkg.github.com"
    }
  }
}

package.json

{
  "name": "root",
  "version": "1.0.0",
  "description": "A monorepo example using Lerna.",
  "private": true,
  "scripts": {
    "postinstall": "lerna bootstrap",
  },
  "devDependencies": { ... }
}

After installing the packages (npm install) the postinstall script will run lerna bootstrap which bootstraps the packages in the current Lerna repo. It will symlink together all Lerna packages that are dependencies of each other

Hoisting

{
  "name": "root",
  "version": "1.0.0",
  "description": "A monorepo example using Lerna.",
  "private": true,
  "scripts": {
    "postinstall": "lerna bootstrap --hoist",
  },
  "devDependencies": { ... }
}

Multiple packages often have duplicate dependencies in their package.jsonfiles.
Lerna can reduce duplicate packages by hoisting the dependencies up to the root (topmost Lerna-project level node_modules directory).
Use lerna bootstrap --hoist in the postinstall script to bootstrap the package after installing them via npm install.

Lerna with Yarn

git clone https://github.com/geersch/lerna.git

git checkout lerna-with-yarn

Lerna with Yarn

Use Yarn as the NPM client.

Install Yarn.
```
$ npm install -g yarn
```

Specify Yarn as the NPM client in lerna.json.

{
  "npmClient": "yarn",
  "packages": ["packages/*"],
  "version": "independent",
}

Run yarn import to generate a yarn.lock from an NPM package-lock.json file.
Remove the node_modules folder and package-lock.json files in the root and package folders.
Run lerna bootstrap in the postinstall script to bootstrap the packages.
```
{
  "postinstall": "lerna bootstrap"
}
```
Run yarn from the root to install the packages and bootstrap the packages.

Yarn Workspaces

git clone https://github.com/geersch/lerna.git

git checkout yarn-workspaces

Yarn Workspaces

Use Yarn Workspaces for handling the dependencies.

Install Yarn.
```
$ npm install -g yarn
```
Run yarn import to generate a yarn.lock from an NPM package-lock.json file.
Remove the node_modules folder and package-lock.json files in the root and package folders.
Yarn Workspaces needs to be defined in the root package.json.
```
{
  "workspaces": ["packages/*"]
}
```
Remove the Lerna package and the lerna.json configuration.
```
$ yarn remove lerna
$ rm -rf lerna.json
```
Remove the scripts that use Lerna in the root package.json file.
Run yarn from the root to install the packages.
Use yarn workspaces run to run scripts in each workspace.

Lerna with Yarn Workspaces

git clone https://github.com/geersch/lerna.git

git checkout lerna-with-yarn-workspaces

Lerna with Yarn Workspaces

Use Yarn Workspaces for handling the dependencies and use Lerna to run commands for the packages and to publish them.

Install Yarn.
```
$ npm install -g yarn
```

Specify Yarn as the NPM client in lerna.json and set useWorkspaces to true to let Yarn manage the dependencies.

{
  "npmClient": "yarn",
  "useWorkspaces": true,
  "packages": ["packages/*"],
  "version": "independent",
}

Yarn Workspaces needs to be defined in the root package.json.
```
{
  "workspaces": ["packages/*"]
}
```
Run yarn import to generate a yarn.lock from an NPM package-lock.json file.
Remove the node_modules folder and package-lock.json files in the root and package folders.
Don't run lerna bootstrap. Remove the postinstall script.
Run yarn from the root to install the packages.

GitHub Packages

Let's publish the packages.

Step 1: Set the name and publishConfig options in your package's package.json.

{
  "name": "@geersch/calculator",
  "publishConfig": { 
    "registry": "https://npm.pkg.github.com/" 
  }
}

Step 2: Authenticate

$ yarn login --registry=https://npm.pkg.github.com/

Step 3: Publish
```
$ yarn publish
```

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

slides.md

slides.md

Monorepos

Agenda

Lerna

What does a monorepo look like?

Lerna Commands

Lerna init

Lerna bootstrap

Lerna run

Lerna exec

Lerna add

Lerna version

Lerna publish

Lerna clean

Lerna info

Lerna with NPM

git clone https://github.com/geersch/lerna.git

Lerna with NPM

Installation

lerna.json

package.json

Hoisting

Lerna with Yarn

git clone https://github.com/geersch/lerna.git

Lerna with Yarn

Yarn Workspaces

git clone https://github.com/geersch/lerna.git

Yarn Workspaces

Lerna with Yarn Workspaces

git clone https://github.com/geersch/lerna.git

Lerna with Yarn Workspaces

GitHub Packages

GitHub Packages

Files

slides.md

Latest commit

History

slides.md

File metadata and controls

Monorepos

Agenda

Lerna

What does a monorepo look like?

Lerna Commands

Lerna init

Lerna bootstrap

Lerna run

Lerna exec

Lerna add

Lerna version

Lerna publish

Lerna clean

Lerna info

Lerna with NPM

git clone https://github.com/geersch/lerna.git

Lerna with NPM

Installation

lerna.json

package.json

Hoisting

Lerna with Yarn

git clone https://github.com/geersch/lerna.git

Lerna with Yarn

Yarn Workspaces

git clone https://github.com/geersch/lerna.git

Yarn Workspaces

Lerna with Yarn Workspaces

git clone https://github.com/geersch/lerna.git

Lerna with Yarn Workspaces

GitHub Packages

GitHub Packages