Use custom hcloud dynamic inventory script

This has multiple benefits:
- We don't have to wait until Ansible 2.8 (which will be when the official hcloud dynamic inventory provider will be included)
- We can expand the script to group servers by labels if required
- We can use the vault to automatically get the hetzner cloud token which is not possible otherwise

ansible.cfg

 [defaults]
-inventory = hosts,inventory_hcloud.yml
+inventory = hosts,hcloud_inventory.py
 library = library
 remote_tmp = $HOME/.ansible/tmp
 remote_user = root

hcloud_inventory.py

+#!/usr/bin/env python
+#
+# Dynamic inventory script for getting infrastructure information from hcloud
+
+import argparse
+import json
+import yaml
+import sys
+
+from hcloud import Client
+
+from ansible import constants as C
+from ansible.parsing.vault import VaultLib
+from ansible.cli import CLI
+from ansible.parsing.dataloader import DataLoader
+
+
+def parse_args():
+    parser = argparse.ArgumentParser(description="Hcloud dynamic inventory script")
+    group = parser.add_mutually_exclusive_group(required=True)
+    group.add_argument('--list', action='store_true')
+    group.add_argument('--host')
+    return parser.parse_args()
+
+
+def list_running_hosts(client):
+    return [server.name for server in client.servers.get_all()]
+
+
+def get_host_details(client, host):
+    server = client.servers.get_by_name(host)
+    return {'ansible_ssh_host': server.public_net.ipv4.ip,
+            'ansible_ssh_port': 22,
+            'ansible_ssh_user': "root"}
+
+
+def main():
+    args = parse_args()
+    loader = DataLoader()
+    vault_secret = CLI.setup_vault_secrets(
+        loader=loader,
+        vault_ids=C.DEFAULT_VAULT_IDENTITY_LIST
+    )
+    vault = VaultLib(vault_secret)
+    decrypted = vault.decrypt(open('misc/vault_hetzner.yml').read())
+    loaded = yaml.load(decrypted)
+    client = Client(token=loaded["hetzner_cloud_api_key"])
+
+    if args.list:
+        hosts = list_running_hosts(client=client)
+        json.dump({'hcloud': hosts}, sys.stdout)
+    else:
+        details = get_host_details(client, args.host)
+        json.dump(details, sys.stdout)
+
+
+if __name__ == '__main__':
+    main()

hosts

@@ -48,9 +48,3 @@ sgp.mirror.pkgbuild.com
 [reproducible-builds]
 repro1.pkgbuild.com
 repro2.pkgbuild.com
-
-[hcloud]
-state.cloud.archlinux.org
-
-[terraform-state]
-state.cloud.archlinux.org

inventory_hcloud.yml

-plugin: hcloud