Get issuer, subject and dates for all certs in a single cert file

check_certs.py

#!/usr/bin/env python3

import os
import sys
import subprocess
import tempfile

f = 'mycerts.pem' if len(sys.argv) == 1 else sys.argv[1]

if os.path.exists(f) and os.path.isfile(f):
    pass
else:
    sys.exit(f'File [{f}] not found.')

start_line = '-----BEGIN CERTIFICATE-----'
end_line = '-----END CERTIFICATE-----'
start_line_key = '-----BEGIN PRIVATE KEY-----'
end_line_key = '-----END PRIVATE KEY-----'
files = []
in_key = False
in_cert = False
with open(f) as infile:
    file_name_prefix = 'cert_'
    seq_no = 0
    outfile = None
    for line in infile:
        if start_line in line:
            in_cert = True
            seq_no += 1
            # file_name = f'{file_name_prefix}{seq_no:02d}'
            fd, file_name = tempfile.mkstemp(text=True)
            outfile = open(fd, 'w')
            outfile.write(line)
            files.append(file_name)
        elif end_line in line:
            outfile.write(line)
            outfile.close()
            in_cert = False
        elif start_line_key in line:
            in_key = True
            # file_name = f'key_01'
            fd, file_name = tempfile.mkstemp(text=True)
            outfile = open(fd, 'w')
            outfile.write(line)
            # files.append(file_name) # do not track key file
        elif end_line_key in line:
            outfile.write(line)
            outfile.close()
            in_key = False
        elif in_cert or in_key:
            outfile.write(line)
#     if not outfile.closed:
#         outfile.close()

# print(files)
cert_type = ''
for idx,f in enumerate(files):
    if idx == 0:
        cert_type = 'server cert'
    elif idx == len(files) - 1:
        cert_type = 'Root CA cert'
    else:
        cert_type = f'Intermediate CA cert {len(files) - idx - 1}'

    print()
    print(f'***** {cert_type} *****')
    cmd = f'openssl x509 -noout -issuer -subject -dates -in {f}'
    call_array = cmd.split()
    # print(call_array)
    resp = subprocess.run(call_array, text=True, capture_output=True)
    if resp and resp.returncode == 0:
        print(f'{resp.stdout.rstrip()}')
    else:
        print(f"Error getting cert information on [{f}]: [{resp.returncode}] {resp.stderr}")
    # deleted cert files
    os.remove(f)