[git] Checkout Jenkins Pipeline Git SCM with credentials?

I was following this tutorial:

node {
  git url: 'https://github.com/joe_user/simple-maven-project-with-tests.git'
  ...
}

However it doesn't tell how to add credentials. Jenkins does have specific "Credentials" section where you define user user&pass, and then get ID for that to use in jobs, but how do I use that in Pipeline instructions?

I tried with:

git([url: '[email protected]:company/repo.git', branch: 'master', credentialsId: '12345-1234-4696-af25-123455'])

no luck:

stderr: Host key verification failed.
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

Is there a way configure the creds in pipeline, or do I have to put SSH-keys to Jenkin's Linux user's .ssh/authorized_keys file?

In ideal world I'd like to have a repository for pipeline jobs and repo-keys, then launch Docker Jenkins, and dynamically add these jobs and keys there without having to configure anything in Jenkins Console.

To explicitly checkout using a specific credentials

    stage('Checkout external proj') {
        steps {
            git branch: 'my_specific_branch',
                credentialsId: 'my_cred_id',
                url: 'ssh://[email protected]/proj/test_proj.git'

            sh "ls -lat"
        }
    }

To checkout based on the configred credentials in the current Jenkins Job

    stage('Checkout code') {
        steps {
            checkout scm
        }
    }

You can use both of the stages within a single Jenkins file.

It solved for me using

checkout scm: ([
                    $class: 'GitSCM',
                    userRemoteConfigs: [[credentialsId: '******',url: ${project_url}]],
                    branches: [[name: 'refs/tags/${project_tag}']]
            ])

Adding you a quick example using git plugin GitSCM:

    checkout([
        $class: 'GitSCM', 
        branches: [[name: '*/master']], 
        doGenerateSubmoduleConfigurations: false, 
        extensions: [[$class: 'CleanCheckout']], 
        submoduleCfg: [], 
        userRemoteConfigs: [[credentialsId: '<gitCredentials>', url: '<gitRepoURL>']]
    ])

in your pipeline

stage('checkout'){
    steps{
        script{
            checkout
        }
    }
}

For what it's worth adding to the discussion... what I did that ended up helping me... Since the pipeline is run within a workspace within a docker image that is cleaned up each time it runs. I grabbed the credentials needed to perform necessary operations on the repo within my pipeline and stored them in a .netrc file. this allowed me to authorize the git repo operations successfully.

withCredentials([usernamePassword(credentialsId: '<credentials-id>', passwordVariable: 'GIT_PASSWORD', usernameVariable: 'GIT_USERNAME')]) {
    sh '''
        printf "machine github.com\nlogin $GIT_USERNAME\n password $GIT_PASSWORD" >> ~/.netrc
        // continue script as necessary working with git repo...
    '''
}

If you want to use ssh credentials,

  git(
       url: '[email protected]<repo_name>.git',
       credentialsId: 'xpc',
       branch: "${branch}"
    )

if you want to use username and password credentials, you need to use http clone as @Serban mentioned.

    git(
       url: 'https://github.com/<repo_name>.git',
       credentialsId: 'xpc',
       branch: "${branch}"
    )