Add delete confirmation + created at examples

docs/examples.rst

@@ -7,6 +7,10 @@ Python-chi Examples
 Cleanup Non-leased Resources
 ============================
 
+
+Opt-in Cleanup using tags
+-------------------------
+
 While baremetal nodes on Chameleon require leases, other resources like networks, and KVM instances
 are persistent, and require manual cleanup. For large projects (e.g. for educational courses), it
 may be useful to have some automatic process to clean up resources after a certain time. Below is
@@ -22,9 +26,10 @@ you can set a "delete_at" tag. This is simply an date string in the future, whic
   network.set_floating_ip_tag(MY_FIP_ADDRESS, f"delete_at={util.date_string_in_future(days=3)}")
   network.set_network_tag(MY_NETWORK_ID, f"delete_at={util.date_string_in_future(days=3)}")
 
-Then, set up the following script to run periodically using something like cron. You'll need
-to set authentication variables (e.g. source an openrc file), and set the site/project. This script
-iterates over the resources in your project, and deletes them if the "delete_at" tag is in the past.
+Then run the following script. You'll need to set authentication variables (e.g. source an openrc file),
+and set the site/project at the beginning. This script iterates over the resources in your project, and
+deletes them if the "delete_at" tag is in the past, if the user manually enters "yes" to confirm.
+You can remove this confirmation in order to automatically run periodically with e.g. cron. 
 
 .. code-block:: python
 
@@ -33,21 +38,55 @@ iterates over the resources in your project, and deletes them if the "delete_at"
   # Find servers with "delete_at" metadata
   for s in server.list_servers():
     if util.should_delete(my_servers.get_metadata().get("delete_at", "")):
-      s.delete()
+      confirm = input(f"Delete server {s.name}? (yes/no): ").strip().lower()
+      if confirm == "yes":
+        s.delete()
 
   # Networks, FIP tags set via tags as a string
   for net in network.list_networks():
     try:
       delete_tag = next(s for s in net["tags"] if s.startswith("delete_at="))
       if util.should_delete(delete_tag.split("=")[1]):
-        network.nuke_network(net_id)
+        confirm = input(f"Delete the network {net['name']}? (yes/no): ").strip().lower()
+        if confirm == "yes":
+          # nuke_network deletes subnets, routers, and the network itself
+          network.nuke_network(net_id)
     except StopIteration:
       pass
 
   for fip in network.list_floating_ips():
     try:
       delete_tag = next(s for s in fip["tags"] if s.startswith("delete_at="))
       if util.should_delete(delete_tag.split("=")[1]):
-        network.deallocate_floating_ip(fip["floating_ip_address"])
+        confirm = input(f"Delete the floating ip {fip['floating_ip_address']}? (yes/no): ").strip().lower()
+        if confirm == "yes":
+          network.deallocate_floating_ip(fip["floating_ip_address"])
     except StopIteration:
-      pass
+      pass
+
+Opt-in Cleanup using `created_at`
+---------------------------------
+
+The above examples are explicitly opt-in, requring the user to set the "delete_at" tag to ensure that
+nothing is deleted unknowlingly. Alternatively, you can monitor the "created_at" field of resources to
+check for long-running resources such as in the following example.
+
+.. code-block:: python
+
+  from datetime import datetime, timedelta
+  from chi import util, server, network
+
+  MAX_AGE = 3  # days
+  for s in server.list_servers():
+      age = util.utcnow() - datetime.fromisoformat(s.created_at)
+      if age > timedelta(days=MAX_AGE):
+        confirm = input(f"Delete server {s.name}? Age is {age}. (yes/no): ").strip().lower()
+        if confirm == "yes":
+          s.delete()
+  for net in network.list_networks():
+      age = util.utcnow() - datetime.fromisoformat(net["created_at"])
+      if age > timedelta(days=MAX_AGE):
+        confirm = input(f"Delete the network {net['name']}? Age is {age}. (yes/no): ").strip().lower()
+        if confirm == "yes":
+          # nuke_network deletes subnets, routers, and the network itself
+          network.nuke_network(net_id)