Using Lerna.js and Azure Devops Pipeline - azure-devops

Question

I'm studying about azuredevops pipelines to a new project. I'm totally new about devops.
In this project, I want to use lerna.js to manage my monorepo and my packages.
Considering that I have those three projects inside my monorepo:
Package 1 (1.0.1)
Package 2 (1.0.0)
Package 3 (1.0.3)
And I want to create a new TAG, which will increase the Package 3 to (1.0.4). How can I trigger an Azure Pipeline just to Package 3? There is any guide?
I watched one talk about monorepos with lerna.js and I'm trying to figure out if Azure Pipelines has one feature similar to what Sail CI does. In the exemple we have this approch:
tasks:
build-package-1:
image: sailci/demo
when:
paths:
- "packages/package-1/**/*"
The company I'm working at is using Azure DevOps, would be awesome know if I can have that feature there.

Answer 1

The closest thing similar to that one is like #Simon Ness wrote multiple pipelines with path filters. Additionally if your packages have similar strucutre and require the same steps to creeate/test/publish package you should consider templates.
The conspet toi handle packages like you described can be similar to below steps.
template.yaml
parameters:
- name: workingDir
type: string
default: package-1
steps:
- script: npm install
workingDiretory: ${{ parameters.workingDir }}
- script: yarn install
workingDiretory: ${{ parameters.workingDir }}
- script: npm run compile
workingDiretory: ${{ parameters.workingDir }}
then pipeline for Package-1 may look like this:
trigger:
branches:
include:
- master
- releases/*
paths:
include:
- Package-1/*
steps:
- template: templates/template.yaml
parameters:
workingDir: Package-1
and for Package-2:
trigger:
branches:
include:
- master
- releases/*
paths:
include:
- Package-2/*
steps:
- template: templates/template.yaml
parameters:
workingDir: Package-2
EDIT
For tag part all you need to do is change trigger section:
trigger:
branches:
include:
- master
- refs/tags/*
and when you create a tag and push it:
git tag release-05
git push origin --tags
your pipeline wil start:
However, trigger works like or condition, so for any change on master or new tag piepline will start. So if you tag another branch (not master) pipeline will start.
This is why you may need to check if your source branch is the one from trigger section:
trigger:
branches:
include:
- master
- refs/tags/*
stages:
- stage: A
condition: eq(variables['Build.SourceBranch'], 'master')
jobs:
- job: JA
steps:
- script: |
echo "This is job Foo."
Above pipeline will run for:
change in master branch
any tag pushed to server, but it runs stage A only if you push tag to master branch

Answer 2

If you're happy to define a separate pipeline for each package take a look at paths in CI triggers.
Tags can be used as a trigger by including the branch - refs/tags/* in the triggers section.