"not a valid OPENSSH private key file" — building a compat layer for seven SSH private-key formats (opens in new tab)

If you wire SSH into WordPress maintenance automation, you'll meet this error sooner or later: SSHException: not a valid OPENSSH private key file "I configured the key file — why?" is the usual reaction. Tracing several real SSH-connection-test failures, the root issue becomes clear: paramiko alone can't read SSH private keys outside the OpenSSH format. In production, hosting providers and key-generation tools produce different formats, and paramiko's standard loader rejects many of them. Her...