[JENKINS-72254] Add support for SSH Certificates

Currently the SSH-Agent plugin doesn't support SSH certificates (e.g. RSA-CERT). It can only load private keys. For example below my ssh-add -l command:2048 

2048 SHA256:FINGERPRINT COMMENT1 (RSA)

2048 SHA256:FINGERPRINT COMMENT2 (RSA)

256 SHA256:FINGERPRINT COMMENT3 (ED25519)

2048 SHA256:FINGERPRINT COMMENT4 (RSA-CERT)

It would be nice to load a certificate from the credential manager and add it to SSH-agent.

At this location: https://github.com/jenkinsci/ssh-agent-plugin/blob/878b53c895119c248eac9dd07da155a47aa99c88/src/main/java/com/cloudbees/jenkins/plugins/sshagent/exec/ExecRemoteAgent.java#L92C33-L92C51 a "*-cert.pub" file should be created besides the private key file so ssh-agent will also load the certificate.

When more information is required please ask!

---
Originally reported by joostr, imported from: Add support for SSH Certificates

• status: Open
  
• priority: Minor
  
• component(s): ssh-agent-plugin
  
• resolution: Unresolved
  
• votes: 0
  
• watchers: 1
  
• imported: 20260604-211335
  

Currently the SSH-Agent plugin doesn't support SSH certificates (e.g. RSA-CERT). It can only load private keys. For example below my ssh-add -l command:2048 



2048 SHA256:FINGERPRINT COMMENT1 (RSA)

2048 SHA256:FINGERPRINT COMMENT2 (RSA)

256 SHA256:FINGERPRINT COMMENT3 (ED25519)

2048 SHA256:FINGERPRINT COMMENT4 (RSA-CERT)



It would be nice to load a certificate from the credential manager and add it to SSH-agent.


At this location: https://github.com/jenkinsci/ssh-agent-plugin/blob/878b53c895119c248eac9dd07da155a47aa99c88/src/main/java/com/cloudbees/jenkins/plugins/sshagent/exec/ExecRemoteAgent.java#L92C33-L92C51 a "*-cert.pub" file should be created besides the private key file so ssh-agent will also load the certificate.


When more information is required please ask!

• environment: Any Jenkins version