sshca: Deploy SSH CA service

[sshca] is a simple web service I wrote to automatically create signed
SSH certificates for hosts' public keys.  It authenticates hosts by
their machine UUID, which it can find using the libvirt API.

[sshca]: https://git.pyrocufflink.net/dustin/sshca

sshca/config.toml

@@ -0,0 +1,11 @@
+machine_ids = "/var/lib/sshca/machine-ids.json"
+
+[ca.host]
+private_key_file = "/run/sshca/secrets/host/key/host-ca-key"
+private_key_passphrase_file = "/run/sshca/secrets/host/passphrase/host-ca-key.passphrase"
+
+[[libvirt]]
+uri = "qemu+ssh://sshca@vmhost0.pyrocufflink.blue/system?keyfile=/run/sshca/libvirt/sshkey"
+
+[[libvirt]]
+uri = "qemu+ssh://sshca@vmhost1.pyrocufflink.blue/system?keyfile=/run/sshca/libvirt/sshkey"