[improve][pip] PIP-277: Add current option in the Clusters list cmd (…

…#20614)

pip/pip-277.md

@@ -0,0 +1,48 @@
+# Motivation
+
+After configuring the geo-replication on Pulsar clusters, the `clusters list` API will return multiple clusters, including the local Pulsar cluster and remote clusters like
+
+```
+bin/pulsar-admin clusters list
+us-west
+us-east
+us-cent
+```
+But in this return, you can't distinguish the local and the remote cluster. When you need to remove the geo-replication configuration, it will be hard to decide which cluster should be removed on replicated tenants and namespaces unless you record the cluster information.
+
+# High Level Design
+
+Add `--current` option to the cluster list cmd and mark the current cluster with `(*)`
+```
+bin/pulsar-admin clusters list --current
+us-west(*)
+us-east
+us-cent
+```
+
+# Detailed Design
+
+## Implementation Details
+
+Add `--current` option to the cluster list cmd
+```
+@Parameter(names = { "-c", "--current" }, description = "Print the current cluster with (*)", required = false)
+private boolean current = false;
+```
+
+```
+void run() throws PulsarAdminException {
+   java.util.List<String> clusters = getAdmin().clusters().getClusters();
+   String clusterName = getAdmin().brokers().getRuntimeConfigurations().get("clusterName");
+   List<String> result = clusters.stream().map(c ->c.equals(clusterName) ? (current ? c + "(*)" : c) : c).collect(Collectors.toList());
+   print(result);
+}
+```
+
+# Links
+
+<!--
+Updated afterwards
+-->
+* Mailing List discussion thread: https://lists.apache.org/thread/800r6ld5wg7bttbywmk38m1qx12hs6nl
+* Mailing List voting thread: https://lists.apache.org/thread/rqn3rd3c4hj11o3b12ygopmztj2yy7pv