ansible/allhosts.py: run ansible on all infra hosts

Example:
```
ansible all -i ~/work/infra-utils/ansible/allhosts.py -a uptime
```

Signed-off-by: Jakub Sokołowski <jakub@status.im>

ansible/allhosts.py

@@ -0,0 +1,83 @@
+#!/usr/bin/env python
+import sys
+import json
+import requests
+from optparse import OptionParser
+
+HELP_DESCRIPTION = '''
+This queries Consul for all available hosts and outputs them in the Ansible
+inventory format, which is JSON with specific keys.
+Assumes existence of Ansible certificate files.
+https://docs.ansible.com/ansible/latest/dev_guide/developing_inventory.html
+'''.strip()
+HELP_EXAMPLE = '''
+Example: ./allhosts.py -l debug -u https://consul.example.org:8400
+'''
+
+
+def parse_opts():
+    parser = OptionParser(description=HELP_DESCRIPTION, epilog=HELP_EXAMPLE)
+    # WARNING: The --list flag is mandatory for use with Ansible. We ignore it.
+    parser.add_option('-l', '--list', action='store_true',
+                      help='Mandatory flag for Ansible. Ignored.')
+    parser.add_option('-d', '--hosts-domain', default='statusim.net',
+                      help='Domain to append to hostnames.')
+    parser.add_option('-u', '--consul-url', default='https://consul.statusim.net:8400',
+                      help='Name of virtual network interface.')
+    parser.add_option('-c', '--cert-chain', default='ansible/files/consul-ca.crt',
+                      help='Path to Consul certificate CA chain.')
+    parser.add_option('-p', '--cert-path', default='ansible/files/consul-client.crt',
+                      help='Path to Consul certificate file')
+    parser.add_option('-k', '--cert-key', default='ansible/files/consul-client.key',
+                      help='Path to Consul certificate key file')
+
+    return parser.parse_args()
+
+def main():
+    (opts, args) = parse_opts()
+
+    data_centers = requests.get(
+        '%s/v1/catalog/datacenters' % opts.consul_url,
+        cert=(opts.cert_path, opts.cert_key),
+        verify=opts.cert_chain,
+    ).json()
+
+    nodes = []
+    for dc in data_centers:
+        nodes.extend(requests.get(
+            '%s/v1/catalog/nodes?dc=%s' % (opts.consul_url,dc),
+            cert=(opts.cert_path, opts.cert_key),
+            verify=opts.cert_chain,
+        ).json())
+
+    # JSON for Ansible
+    out = {'_meta':{'hostvars':{}}}
+    for node in nodes:
+        out['_meta']['hostvars'][node['Node']] = {
+            "dns_entry":    '%s.%s' % (node['Node'], opts.hosts_domain),
+            "hostname":     node['Node'],
+            "ansible_host": node['Address'],
+            "data_center":  node['Datacenter'],
+            "env":          node['Meta']['env'],
+            "stage":        node['Meta']['stage'],
+        }
+
+        dc_group = out.setdefault(
+            node['Datacenter'],
+            {'children': [], 'hosts': [], 'vars': {} },
+        )
+        dc_group['hosts'].append(node['Node'])
+
+        fleet_group = out.setdefault(
+            '%s.%s' % (node['Meta']['env'],node['Meta']['stage']),
+            {'children': [], 'hosts': [], 'vars': {} },
+        )
+        fleet_group['hosts'].append(node['Node'])
+
+    out['all'] = { 'hosts': [node['Node'] for node in nodes] }
+
+    print(json.dumps(out, indent=2))
+
+
+if __name__ == '__main__':
+    main()