Deploy a Monorepo with Jenkins and Gitlab webhooks

The monorepo is managed by Lerna.
As you push to Gitlab, it triggers a Jenkins job.
This job checkouts the repository, and loads the tasks package Jenkinsfile at: packages/tasks/Jenkinsfile. There we list all deployable packages. Mostly the packages are not deployable and used as dependencies.
Each deployable package has one Jenkinsfile at packages/PACKAGE/scripts/Jenkinsfile that knows how to deploy itself.
The tasks package Jenkinsfile compares this commit with last successful deploy and find all changed packages and only load Jenkisnfile of those packages.

The structure of the monorepo is as follows:

  |
  |-- packages/
  |           /tasks/Jenkinsfile
  |           /notify/
  |                  /scripts/Jenkinsfile
  |           /email/

in which the notify package is a deployable one, and email package is a dependency for notify.

Development flow

install dependencies
```
lerna bootstrap --hoist
```
add dependencies Here adding @company/email to @company/notify. As you notice, we use @company to scope npm packages.
```
lerna add @company/email --scope @company/notify
```
run only one package
```
cd packages/notify
npm start
```
run all packages
```
lerna run start
```

lerna publish --registry http://registry.company.com