Turn private keys in Gravity registry into .ssh/authorized_keys

extract-gravity-keys.sh

#!/bin/sh
# ./extract-gravity-keys.sh PATH_TO_PARENT_FOLDER_OF_GRAVITY >> ~/.ssh/authorized_keys
BASE="${1:-.}"
python3 -c "
import base64, struct, json, glob, os, sys

def pem_to_ssh_ed25519(pem):
    b64 = ''.join(l for l in pem.split('\n') if not l.startswith('-----'))
    der = base64.b64decode(b64)
    raw = der[-32:]
    algo = b'ssh-ed25519'
    parts = [
        struct.pack('>I', len(algo)) + algo,
        struct.pack('>I', len(raw)) + raw,
    ]
    return base64.b64encode(b''.join(parts)).decode()

base = sys.argv[1]
for f in sorted(glob.glob(os.path.join(base, 'gravity/registry/*.json'))):
    with open(f) as fh:
        d = json.load(fh)
    pub = pem_to_ssh_ed25519(d['public_key'])
    print(f'command=\"cat /var/lib/gravity/registry.json\" ssh-ed25519 {pub} {d[\"organization\"]}')
" "$BASE"