Information
Verify that the Docker server certificate key file (the file that is passed alongwith --tlskey parameter) has permissions of 400.
Rationale:
The Docker server certificate key file should be protected from any tampering or unneeded reads. It holds the private key for the Docker server certificate. Hence, it must have permissions of 400 to maintain the integrity of the Docker server certificate.
Solution
chmod 400 <path to Docker server certificate key file>
This would set the Docker server certificate key file permissions to 400.
Impact:
None.
Default Value:
By default, the permissions for Docker server certificate key file might not be 400. The default file permissions are governed by the system or user specific umask values.