Blue-Green Upgrade guide updates

rabbitmqadmin v2 provides a new set of commands
that greatly simplify the task of enabling
queue federation of all policies.

To make this update possible for the 3.13
edition, this backports some Policies
guide changes to that edition.
After all, the rabbitmqadmin v2 commands
in question can be used with 3.13.x nodes
as well as 4.x ones.

Author: michaelklishin

docs/blue-green-upgrade.md

@@ -63,15 +63,38 @@ rabbitmqctl set_parameter federation-upstream blue \
   '{"uri":"amqp://node-in-blue-cluster"}'
 ```
 
-Then define a policy matching all queues which configure `blue` as the upstream:
+Then define a [policy](./policies) or a number of policies, collectively matching all queues
+which configure `blue` as the upstream:
 
 ```bash
 rabbitmqctl set_policy --apply-to queues blue-green-migration ".*" \
   '{"federation-upstream":"blue"}'
 ```
 
-Please read the guides linked above and the
-[federation reference](./federation-reference) for further details.
+:::tip
+
+The above example is a great oversimplification.
+
+In practice, some queues will be already matched by a policy,
+and some might not be.
+
+[`rabbitmqadmin v2`](./management-cli) provides a set of commands
+that allow the operator to
+
+1. [Patch (partially update)](./policies#patching) policies
+2. Temporarily [override existing policies](./policies#override)
+to include a key that enabled queue federation
+3. [Declare a blanket policy](./policies#blanket) to match all other queues
+to enable federation for them
+
+Use a combination of these features to enable queue federation
+between the clusters for all queues, whether they already have
+a policy that applies to them or not.
+
+:::
+
+Please refer to the [policies](./policies) and
+[federation reference](./federation-reference) guides to learn more.
 
 ## Migrate Consumers Over {#migrate-consumers}
 

versioned_docs/version-3.13/blue-green-upgrade.md

@@ -67,15 +67,38 @@ rabbitmqctl set_parameter federation-upstream blue \
   '{"uri":"amqp://node-in-blue-cluster"}'
 ```
 
-Then define a policy matching all queues which configure `blue` as the upstream:
+Then define a [policy](./policies) or a number of policies, collectively matching all queues
+which configure `blue` as the upstream:
 
 ```bash
 rabbitmqctl set_policy --apply-to queues blue-green-migration ".*" \
   '{"federation-upstream":"blue"}'
 ```
 
-Please read the guides linked above and the
-[federation reference](./federation-reference) for further details.
+:::tip
+
+The above example is a great oversimplification.
+
+In practice, some queues will be already matched by a policy,
+and some might not be.
+
+[`rabbitmqadmin v2`](./management-cli) provides a set of commands
+that allow the operator to
+
+1. [Patch (partially update)](./policies#patching) policies
+2. Temporarily [override existing policies](./policies#override)
+to include a key that enabled queue federation
+3. [Declare a blanket policy](./policies#blanket) to match all other queues
+to enable federation for them
+
+Use a combination of these features to enable queue federation
+between the clusters for all queues, whether they already have
+a policy that applies to them or not.
+
+:::
+
+Please refer to the [policies](./policies) and
+[federation reference](./federation-reference) guides to learn more.
 
 ## Migrate Consumers Over {#migrate-consumers}