Azure DevOps CI agent error while excuting npm install

Issue

I have configured Azure DevOps CI pipe for Angular 13 WEB APP. The Node version is 14.17 and NPM 6.14.13 used azure agent Ubuntu 20.04 LTS. Below you can see what I included to my build

resources:
  repositories:
  - repository: self
    type: git
    ref: refs/heads/development
jobs:
- job: Job_1
  displayName: Agent job 1
  pool:
    vmImage: ubuntu-20.04
  steps:
  - checkout: self
  - task: NodeTool@0
    displayName: Use Node 14.17.x
    inputs:
      versionSpec: 14.17.x
  - task: CmdLine@2
    displayName: Install Anguler
    inputs:
      script: npm install -g @angular/cli
  - task: Npm@1
    displayName: npm install
    inputs:
      verbose: false
  - task: CmdLine@1
    displayName: Run ng
    inputs:
      filename: ng
      arguments: build
  - task: PublishBuildArtifacts@1
    displayName: 'Publish Artifact: dist'
    inputs:
      PathtoPublish: dist
      ArtifactName: dist 

The problem is when it comes to npm install returning following errror

2022-07-05T08:50:59.0085431Z npm WARN config global `--global`, `--local` are deprecated. Use `--location=global` instead.
2022-07-05T08:50:59.0086707Z npm ERR! code ERESOLVE
2022-07-05T08:50:59.0087276Z npm ERR! ERESOLVE could not resolve
2022-07-05T08:50:59.0087839Z npm ERR! 
2022-07-05T08:50:59.0088385Z npm ERR! While resolving: ng-select2@1.4.1
2022-07-05T08:50:59.0089028Z npm ERR! Found: select2@4.1.0-rc.0
2022-07-05T08:50:59.0089656Z npm ERR! node_modules/select2
2022-07-05T08:50:59.0090324Z npm ERR!   select2@"^4.1.0-rc.0" from the root project
2022-07-05T08:50:59.0091059Z npm ERR! 
2022-07-05T08:50:59.0091557Z npm ERR! Could not resolve dependency:
2022-07-05T08:50:59.0092182Z npm ERR! peer select2@"^4.0.x" from ng-select2@1.4.1
2022-07-05T08:50:59.0092812Z npm ERR! node_modules/ng-select2
2022-07-05T08:50:59.0093479Z npm ERR!   ng-select2@"^1.4.1" from the root project
2022-07-05T08:50:59.0094043Z npm ERR! 
2022-07-05T08:50:59.0094606Z npm ERR! Conflicting peer dependency: select2@4.0.13
2022-07-05T08:50:59.0095230Z npm ERR! node_modules/select2
2022-07-05T08:50:59.0095824Z npm ERR!   peer select2@"^4.0.x" from ng-select2@1.4.1
2022-07-05T08:50:59.0096597Z npm ERR!   node_modules/ng-select2
2022-07-05T08:50:59.0097203Z npm ERR!     ng-select2@"^1.4.1" from the root project
2022-07-05T08:50:59.0097691Z npm ERR! 
2022-07-05T08:50:59.0098212Z npm ERR! Fix the upstream dependency conflict, or retry
2022-07-05T08:50:59.0098870Z npm ERR! this command with --force, or --legacy-peer-deps
2022-07-05T08:50:59.0099604Z npm ERR! to accept an incorrect (and potentially broken) dependency resolution.
2022-07-05T08:50:59.0102846Z npm ERR! 
2022-07-05T08:50:59.0103438Z npm ERR! See C:\npm\cache\eresolve-report.txt for a full report.
2022-07-05T08:50:59.0103769Z 
2022-07-05T08:50:59.0104331Z npm ERR! A complete log of this run can be found in:
2022-07-05T08:50:59.0105127Z npm ERR!     C:\npm\cache\_logs\2022-07-05T08_50_56_733Z-debug-0.log
2022-07-05T08:50:59.1265632Z ##[warning]Couldn't find a debug log in the cache or working directory
2022-07-05T08:50:59.1289161Z ##[error]Error: Npm failed with return code: 1
2022-07-05T08:50:59.1322525Z ##[section]Finishing: npm install

Can anyone help me on this?

Solution

This has nothing to do with the Azure DevOps CI pipeline per se. You have a problem with https://nodejs.org/en/blog/npm/peer-dependencies. In summary, an upstream package relies on a supporting package being installed downstream by the hosting application and versions can be quite restricted. The workaround (as per the error message) is to use npm install --legacy-peer-deps https://docs.npmjs.com/cli/v7/using-npm/config#legacy-peer-deps . You can find out what the peer dependencies for a package are by using the command npm info ng-select2 peerDependencies or specific version npm info ng-select2@1.4.1 peerDependencies.

Result below. Notice that ng-select2@1.4.1 relies on select2@^4.0.x.

Have you installed select2@^4.0.x ?

{
  '@angular/common': '^13.0.0',
  '@angular/core': '^13.0.0',
  '@types/jquery': '3.5.x',
  '@types/select2': '^4.0.x',
  select2: '^4.0.x',
  jquery: '3.5.x'
}

Installing the correct version of npm install select2@^4.0.0 should solve your problem.

In your package.json:

"select2": "^4.0.0"

Answered By - Robin Webb