Accessing saved Credentials from a slave node

[Andrew Finley]

Hi everyone,

I've run into an issue with the Jenkins plugin I'm working on and I could use some help.  The plugin uses a REST API with an API Token, and the API Token is stored in the Credentials plugin as a 'Secret Text' type.  

The plugin works fine when run from the master Jenkins instance, but if it's run on a slave node it crashes when trying to access the Credentials.

Below is the code we are using to access the credentials:

public String getCredentialWithId(String credentialId) {
 List<StringCredentials> stringCredentials = fetchStringCredentials();
        StringCredentials credential = CredentialsMatchers.firstOrNull(stringCredentials,
                                                                       CredentialsMatchers.withId(credentialId));
        String secret = null;
        if (credential != null) {
            secret = credential.getSecret().getPlainText();
        }
        return secret;
    }


private List<StringCredentials> fetchStringCredentials() {
 return CredentialsProvider.lookupCredentials(
 StringCredentials.class,
 Jenkins.getInstance(),
 ACL.SYSTEM,
 Collections.<DomainRequirement>emptyList()
 );
}

The problem exists with 'Jenkins.getInstance()' in 'fetchStringCredentials()'.  This will return 'null' if it's not run on the master Jenkins instance.  Is there a way to access credentials stored in the Credentials

plugin when running on a slave node?  

I've tried using the 'CredentialsProvider.findCredentialById()' function to get the Credential in the below example.

    public String getCredentialsWithIdFromRun(String credentialsId, Run run) {
        if (StringUtils.isBlank(credentialsId)) {
            return null;
        }
        StringCredentials result = CredentialsProvider.findCredentialById(
                credentialsId,
                StringCredentials.class,
                run,
                Collections.<DomainRequirement>emptyList());

        return result.getSecret().getPlainText();
    }

However, this gives me the wrong value for the Credential ID (not null).  

Any advice would be appreciated.

Thanks,

Andrew

[Jesse Glick]

On Mon, Feb 11, 2019 at 6:24 PM Andrew Finley <afi...@arxan.com> wrote:
> The problem exists with 'Jenkins.getInstance()' in 'fetchStringCredentials()'. This will return 'null' if it's not run on the master Jenkins instance. Is there a way to access credentials stored in the Credentials
> plugin when running on a slave node?

No, which is why you should look up the secret in the master-side
code, and then include that in a serializable field in your
`MasterToSlave[File]Callable`.