Initial commit: Basic CLI and checks

Certo supports polling one or several hostnames.
Output can be human-readable or JSON.

certo/output.py

@@ -0,0 +1,34 @@
+import json
+from typing import List
+
+from certo.checks.hostname import CertCheckResult
+
+
+def json_output(cert_check_results: List[CertCheckResult]):
+    def make_check_serialisable(check):
+        """
+        Converts a CertCheckResult for json serialisation
+        :param check: CertCheckResult as output by checks
+        :return: check as dict() with appropriate type conversions for json.dumps
+        """
+        ret = check._asdict()
+        if check.expiration_date:
+            ret["expiration_date"] = check.expiration_date.strftime("%c %Z")
+        return ret
+
+    return json.dumps(
+        list(map(lambda check: make_check_serialisable(check), cert_check_results)),
+        indent=4,
+    )
+
+
+def default_output(cert_check_results: List[CertCheckResult]):
+    res = list()
+    for check in cert_check_results:
+        result = f"[{'PASS' if check.check_successful else 'FAIL'}] Check host {check.hostname}"
+        if check.debug:
+            result += f" - {check.debug}"
+        if check.expiration_date:
+            result += f" - Certificate expires on {check.expiration_date} {check.expiration_date.tzname()}"
+        res.append(result)
+    return "\n".join(res)