I am using the REST API to create a SSH slave using a username/privatekey (and not a credentials-id, doesn't match my use case).

The request looks like:

{{
https://integration.wikimedia.org/ci/computer/doCreateItem?
json=
{
"labelString": "ci-jessie-wikimedia",
"launcher":

{ "host": "10.68.17.84", "port": 22, "privatekey": "/var/lib/nodepool/.ssh/nodepoolmanager_id_rsa", "stapler-class": "hudson.plugins.sshslaves.SSHLauncher", "username": "nodepoolmanager" }

,
"mode": "EXCLUSIVE",
"name": "ci-jessie-wikimedia-33",
"nodeDescription": "Dynamic single use ci-jessie-wikimedia node",
"nodeProperties":

{ "stapler-class-bag": "true" }

,
"numExecutors": 1,
"remoteFS": "/home/jenkins",
"retentionStrategy":

{ "stapler-class": "hudson.slaves.RetentionStrategy$Always" }

,
"type": "hudson.slaves.DumbSlave$DescriptorImpl"
}
&type=hudson.slaves.DumbSlave$
DescriptorImpl&name=ci-jessie-wikimedia-33
}}

There is a NPE somewhere between the credentials plugin and the sshslaves plugin:
{{
Caused by: java.lang.NullPointerException
at com.cloudbees.plugins.credentials.matchers.IdMatcher.<init>(IdMatcher.java:49)
at com.cloudbees.plugins.credentials.CredentialsMatchers.withId(CredentialsMatchers.java:112)
at hudson.plugins.sshslaves.SSHLauncher.lookupSystemCredentials(SSHLauncher.java:291)
at hudson.plugins.sshslaves.SSHLauncher.<init>(SSHLauncher.java:268)
}}

The code state that a NPE is raised. Seems there is no way to create a SSH slave without a credentials-id which is rather annoying

Downstream bug: https://phabricator.wikimedia.org/T103120