Jenkins Sshagent plugin in slave not working as expected - jenkins

Question

I am trying to use the sshagent and credentials plugin to execute couple of git commands on a remote repo in a jenkins pipeline script .
I am trying to do this checkout some files from a large repo . This runs on a docker slave .
sshagent(['a5f11347-dff6-4586-ae77-34adeffb0063']) {
script {
sh 'git archive --remote=ssh://git#git.comp.com/something.git HEAD Jenkinsfile | tar -x'
sh 'git archive --remote=ssh://git#git.comp.com/something.git HEAD:pipeline/ | tar -x;'
}
}
But it fails with a hostkey verification failed error. Any insight on why this is failing .
If i do a
checkout([$class: 'GitSCM', branches: [[name: "${BRANCH_NAME}"]],
doGenerateSubmoduleConfigurations: false,
extensions: [[$class: 'CloneOption', depth: 0, noTags: false, reference: '', shallow: true],
[$class: 'CloneOption', noTags: true, reference: '', shallow: true],
[$class: 'SparseCheckoutPaths', sparseCheckoutPaths: [[path: 'Jenkinsfile'], [path: 'pipeline/*']]]],
submoduleCfg: [], userRemoteConfigs: [[credentialsId: 'a5f11347-dff6-4586-ae77-34adeffb0063',
url: 'ssh://git#git.comp.com/something.git']]])
it works fine ,but the large repo is fetched ,which i want to avoid

Answer 1

Regarding the host key verification problem, you need to add the host key for git.comp.com to your SSH known_hosts file. Try integrating the following command in your Jenkins script before the sshagent block:
ssh-keyscan git.comp.com >> ~/.ssh/known_hosts
This worked for me.
See Jenkins ssh-agent starts and then stops immediately in pipeline build for more info.