Runner with Client Authentication

How to configure gitlab-runner when client authentication is enabled via Nginx?

Thank you.

Setup: GitLab on-prem using built-in Nginx Server with Client certificates enabled. Trying to register a runner get the below -

ERROR: Registering runner... failed                 runner=GR134894 status=400 Bad Request
PANIC: Failed to register the runner.

Using curl

curl -v --key /etc/pki/tls/certs/gitlab.key --cert /etc/pki/tls/certs/gitlab.cer --cacert /etc/pki/ca-trust/source/anchors/ca.pem

* About to connect() to port 8443 (#0)
*   Trying
* Connected to ( port 8443 (#0)
* Initializing NSS with certpath: sql:/etc/pki/nssdb
*   CAfile: /etc/pki/ca-trust/source/anchors/DoD_CAs.pem
  CApath: none
* unable to load client key: -8178 (SEC_ERROR_BAD_KEY)
* NSS error -8178 (SEC_ERROR_BAD_KEY)
* Peer's public key is invalid.
* Closing connection 0
curl: (58) unable to load client key: -8178 (SEC_ERROR_BAD_KEY)

Use the tls-ca-file, tls-cert-file and tls-key-file. More info here.

Thanks you very much, I now have a runner