PMM-14665 Skip nodes internal to a PMM deployment when adding a service

public/app/percona/add-instance/components/AddRemoteInstance/AddRemoteInstance.service.test.tsx

@@ -70,9 +70,11 @@ describe('AddRemoteInstanceService:: ', () => {
       pmm_agent_id: {
         value: 'pmm-server',
       },
+      // the exporter runs on the PMM Server node, which is what makes the metrics mode PULL
       node: {
         value: 'node1',
         label: 'node1',
+        isPMMServerNode: true,
       },
     };
 

public/app/percona/add-instance/components/AddRemoteInstance/AddRemoteInstance.service.tsx

@@ -1,6 +1,5 @@
 import { CancelToken } from 'axios';
 
-import { PMM_SERVER_NODE_AGENT_ID } from 'app/percona/add-instance/components/AddRemoteInstance/FormParts/NodesAgents/NodesAgents.constants';
 import { MetricsMode } from 'app/percona/inventory/Inventory.types';
 import { Databases } from 'app/percona/shared/core';
 import { apiManagement } from 'app/percona/shared/helpers/api';
@@ -207,7 +206,7 @@ export const toPayload = (values: any, discoverName?: string, type?: InstanceAva
 
   data.pmm_agent_id = values.pmm_agent_id.value;
 
-  if (data.pmm_agent_id === PMM_SERVER_NODE_AGENT_ID || data.node.isPMMServerNode) {
+  if (data.node.isPMMServerNode) {
     data.metrics_mode = MetricsMode.PULL;
   } else {
     data.metrics_mode = MetricsMode.PUSH;

public/app/percona/add-instance/components/AddRemoteInstance/FormParts/NodesAgents/NodesAgents.test.tsx

@@ -7,6 +7,7 @@ import { InventoryService } from 'app/percona/inventory/Inventory.service';
 import {
   nodesMockMultipleAgentsNoPMMServer,
   nodesMock,
+  nodesMockHA,
   nodesMockOneAgentNoPMMServer,
 } from 'app/percona/inventory/__mocks__/Inventory.service';
 import * as NodesReducer from 'app/percona/shared/core/reducers/nodes/nodes';
@@ -55,6 +56,33 @@ describe('Nodes Agents:: ', () => {
     await waitFor(() => expect(screen.getByTestId('node')).toHaveTextContent(nodesMock[0].node_id));
   });
 
+  it('should not offer nodes internal to the PMM deployment', async () => {
+    jest.spyOn(InventoryService, 'getNodes').mockReturnValue(Promise.resolve({ nodes: nodesMockHA }));
+
+    setup();
+
+    await waitFor(() => expect(fetchNodesActionActionSpy).toHaveBeenCalled());
+
+    selectEvent.openMenu(screen.getByLabelText('Nodes'));
+
+    // the PostgreSQL cluster backing PMM and the PMM Server nodes themselves
+    expect(screen.queryByText('pmm-pmm-ha-pg-db-instance1-qjjl-0')).not.toBeInTheDocument();
+    expect(screen.queryByText('pmm-ha-0')).not.toBeInTheDocument();
+    // the client is both the selected value and an option, which also proves the menu is open and
+    // the assertions above are not passing vacuously
+    expect(screen.getAllByText('pmm-pmm-ha-client-0').length).toBeGreaterThan(1);
+  });
+
+  it('should preselect the pre-provisioned client in an HA deployment', async () => {
+    jest.spyOn(InventoryService, 'getNodes').mockReturnValue(Promise.resolve({ nodes: nodesMockHA }));
+
+    setup();
+
+    await waitFor(() => expect(fetchNodesActionActionSpy).toHaveBeenCalled());
+
+    await waitFor(() => expect(screen.getByTestId('node')).toHaveTextContent('pmm-ha-client-0-id'));
+  });
+
   it('should not pick any agent when the selected node is not pmm-server', async () => {
     jest
       .spyOn(InventoryService, 'getNodes')

public/app/percona/add-instance/components/AddRemoteInstance/FormParts/NodesAgents/NodesAgents.tsx

@@ -4,13 +4,9 @@ import { useField } from 'react-final-form';
 import { useStyles2 } from '@grafana/ui';
 import { Messages } from 'app/percona/add-instance/components/AddRemoteInstance/FormParts/FormParts.messages';
 import { getStyles } from 'app/percona/add-instance/components/AddRemoteInstance/FormParts/FormParts.styles';
-import {
-  PMM_SERVER_NODE_AGENT_ID,
-  PMM_SERVER_NODE_ID,
-} from 'app/percona/add-instance/components/AddRemoteInstance/FormParts/NodesAgents/NodesAgents.constants';
 import { NodesAgentsProps } from 'app/percona/add-instance/components/AddRemoteInstance/FormParts/NodesAgents/NodesAgents.types';
 import { GET_NODES_CANCEL_TOKEN } from 'app/percona/inventory/Inventory.constants';
-import { AgentsOption, NodesOption } from 'app/percona/inventory/Inventory.types';
+import { NodesOption } from 'app/percona/inventory/Inventory.types';
 import { SelectField } from 'app/percona/shared/components/Form/SelectFieldCore';
 import { useCancelToken } from 'app/percona/shared/components/hooks/cancelToken.hook';
 import { nodesOptionsMapper } from 'app/percona/shared/core/reducers/nodes';
@@ -45,28 +41,23 @@ export const NodesAgents: FC<NodesAgentsProps> = ({ form }) => {
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, []);
 
-  const changeAgentValue = (value: AgentsOption) => {
-    if (!form?.getState().values?.address) {
-      if (value.label !== PMM_SERVER_NODE_AGENT_ID) {
-        form?.change('address', 'localhost');
-      } else {
-        form?.change('address', '');
-      }
+  // A service monitored by the PMM Server node itself is a remote one, so its address is left for
+  // the user to fill in. Any other node runs next to what it monitors, hence the localhost default.
+  const prefillAddress = (node?: NodesOption) => {
+    if (node && !form?.getState().values?.address) {
+      form?.change('address', node.isPMMServerNode ? '' : 'localhost');
     }
   };
 
   const setNodeAndAgent = (value: NodesOption) => {
     form?.change('node', value);
 
-    let selectedAgent: AgentsOption | undefined;
-    if (value.agents && value.agents?.length > 1) {
-      selectedAgent = value.agents.find((item) => item.value === PMM_SERVER_NODE_AGENT_ID);
-    } else if (value.agents && value.agents?.length === 1) {
-      selectedAgent = value.agents[0];
-    }
+    // A node running several pmm-agents is ambiguous, so the agent is left for the user to pick.
+    const selectedAgent = value.agents?.length === 1 ? value.agents[0] : undefined;
+
     if (selectedAgent) {
       form?.change('pmm_agent_id', selectedAgent);
-      changeAgentValue(selectedAgent);
+      prefillAddress(value);
     } else {
       form?.change('pmm_agent_id', undefined);
     }
@@ -76,13 +67,13 @@ export const NodesAgents: FC<NodesAgentsProps> = ({ form }) => {
     if (nodesOptions.length === 0) {
       loadData();
     } else if (!selectedNode) {
-      // preselect pmm-server node
-      const pmmServerNode =
-        nodesOptions.find((node) => node.value === PMM_SERVER_NODE_ID) ||
-        nodesOptions.find((node) => node.isPMMServerNode);
+      // PMM Server reports the nodes it does not want monitoring delegated to, and they are already
+      // filtered out. Whatever is left is eligible, the PMM Server node being the natural default
+      // where it is still offered - a single-node deployment has no other node to pick.
+      const preselectedNode = nodesOptions.find((node) => node.isPMMServerNode) ?? nodesOptions[0];
 
-      if (pmmServerNode) {
-        setNodeAndAgent(pmmServerNode);
+      if (preselectedNode) {
+        setNodeAndAgent(preselectedNode);
       }
     }
     // eslint-disable-next-line react-hooks/exhaustive-deps
@@ -112,7 +103,7 @@ export const NodesAgents: FC<NodesAgentsProps> = ({ form }) => {
           options={selectedNode?.agents || []}
           name="pmm_agent_id"
           data-testid="agents-selectbox"
-          onChange={(event) => changeAgentValue(event as AgentsOption)}
+          onChange={() => prefillAddress(selectedNode)}
           className={styles.selectField}
           aria-label={Messages.form.labels.nodesAgents.agents}
           validators={selectedNode ? [validators.required] : undefined}

public/app/percona/inventory/Inventory.types.ts

@@ -160,6 +160,7 @@ export interface NodeDB {
   status: ServiceStatus;
   services?: ServiceNodeListDB[];
   is_pmm_server_node: boolean;
+  is_pmm_internal_node?: boolean;
 }
 
 export interface NodeListDBPayload {

public/app/percona/inventory/__mocks__/Inventory.service.ts

@@ -72,6 +72,45 @@ export const nodesMock = [
   },
 ];
 
+const haNodeMock = (nodeId: string, nodeName: string, isPMMServerNode: boolean, isInternalNode = false) => ({
+  node_id: nodeId,
+  node_type: 'generic',
+  node_name: nodeName,
+  is_pmm_server_node: isPMMServerNode,
+  is_pmm_internal_node: isInternalNode,
+  machine_id: '',
+  distro: '',
+  node_model: '',
+  container_id: '',
+  container_name: '',
+  address: '10.1.2.3',
+  region: '',
+  az: '',
+  custom_labels: {},
+  created_at: '2026-07-27T08:05:31.079300Z',
+  updated_at: '2026-07-27T08:05:31.079300Z',
+  status: ServiceStatus.UP,
+  agents: [
+    {
+      agent_id: `${nodeId}-pmm-agent`,
+      agent_type: AgentType.pmmAgent,
+      status: ServiceAgentStatus.RUNNING,
+      is_connected: true,
+    },
+  ],
+  services: [],
+});
+
+// Mimics a PMM HA deployment as PMM Server reports it: the PMM Server Nodes and the Nodes of PMM's
+// own PostgreSQL cluster are internal, leaving the pre-provisioned PMM Client to be monitored with.
+export const nodesMockHA = [
+  haNodeMock('pmm-ha-0-id', 'pmm-ha-0', true, true),
+  haNodeMock('pmm-ha-1-id', 'pmm-ha-1', true, true),
+  haNodeMock('pmm-ha-2-id', 'pmm-ha-2', true, true),
+  haNodeMock('pmm-ha-client-0-id', 'pmm-pmm-ha-client-0', false),
+  haNodeMock('pg-db-instance1-id', 'pmm-pmm-ha-pg-db-instance1-qjjl-0', false, true),
+];
+
 export const nodesMockMultipleAgentsNoPMMServer = [
   {
     node_id: '324234234',

public/app/percona/shared/core/reducers/nodes/nodes.utils.ts

@@ -58,6 +58,9 @@ export const nodeFromDbMapper = (nodeFromDb: NodeDB[]): Node[] => {
 
 export const nodesOptionsMapper = (nodeFromDb: NodeDB[]): NodesOption[] =>
   nodeFromDb
+    // Nodes belonging to a PMM deployment's own infrastructure (e.g. the HA persistence layer)
+    // are dedicated and must not be delegated any monitoring workloads.
+    .filter((node) => !node.is_pmm_internal_node)
     .map((node) => {
       const agents = (node.agents || [])
         .filter((agent) => agent.agent_type === AgentType.pmmAgent)