Add test case for ignore_external_masters + failover

The test checks that failover works even when the master of the monitored
cluster is a slave to an external masters. The test also verifies that the
servers do not get unexpected status labels.

maxscale-system-test/mysqlmon_external_master.cpp

@@ -0,0 +1,114 @@
+/**
+ * Test monitoring and failover with ignore_external_masters=true
+ */
+#include "testconnections.h"
+
+#include <thread>
+
+#define DOWN                     "Down"
+#define RUNNING                  "Running"
+#define MASTER                   "Master"
+#define SLAVE                    "Slave"
+
+const StringSet master_running = {MASTER, RUNNING};
+const StringSet slave_running  = {SLAVE, RUNNING};
+const StringSet running        = {RUNNING};
+const StringSet down           = {DOWN};
+
+void check_status(TestConnections& test, const char* server, const StringSet& expected, const char* message)
+{
+    StringSet state = test.get_server_status(server);
+    test.assert(state == expected, "%s: %s", message, dump_status(state, expected).c_str());
+}
+
+static bool is_running = true;
+
+void writer_func(TestConnections* test)
+{
+    while (is_running)
+    {
+        MYSQL* conn = open_conn(test->maxscales->rwsplit_port[0], test->maxscales->IP[0],
+                                "test", "test", false);
+
+        for (int i = 0; i < 100; i++)
+        {
+            if (execute_query_silent(conn, "INSERT INTO test.t1 VALUES (SELECT SLEEP(0.5))"))
+            {
+                sleep(1);
+                break;
+            }
+        }
+
+        mysql_close(conn);
+    }
+}
+
+int main(int argc, char** argv)
+{
+    Mariadb_nodes::require_gtid(true);
+    TestConnections test(argc, argv);
+
+    // Create a table and a user and start a thread that does writes
+    test.repl->connect();
+    execute_query(test.repl->nodes[0], "CREATE OR REPLACE TABLE test.t1 (id INT)");
+    execute_query(test.repl->nodes[0], "DROP USER IF EXISTS 'test'@'%%'");
+    execute_query(test.repl->nodes[0], "CREATE USER 'test'@'%%' IDENTIFIED BY 'test'");
+    execute_query(test.repl->nodes[0], "GRANT INSERT, SELECT, UPDATE, DELETE ON *.* TO 'test'@'%%'");
+    test.repl->sync_slaves();
+    std::thread thr(writer_func, &test);
+
+    test.tprintf("Start by having the current master replicate from the external server");
+    test.repl->connect();
+    test.repl->replicate_from(0, 3);
+    sleep(5);
+    check_status(test, "server1", master_running, "server1 should be the master");
+    check_status(test, "server2", slave_running, "server2 should be a slave");
+    check_status(test, "server3", slave_running, "server3 should be a slave");
+
+    test.tprintf("Stop server1, expect server2 to be promoted as the master");
+    test.repl->stop_node(0);
+    sleep(10);
+
+    check_status(test, "server1", down, "server1 should be down");
+    check_status(test, "server2", master_running, "server2 should be the master");
+    check_status(test, "server3", slave_running, "server3 should be a slave");
+
+    test.tprintf("Configure master-master replication between server2 and the external server");
+    test.repl->replicate_from(1, 3);
+    test.repl->replicate_from(3, 1);
+    sleep(10);
+    check_status(test, "server2", master_running, "server2 should still be the master");
+    check_status(test, "server3", slave_running, "server3 should be a slave");
+
+    test.tprintf("Start server1, expect it to rejoin the cluster");
+    test.repl->start_node(0);
+    sleep(10);
+    check_status(test, "server1", slave_running, "server1 should be a slave");
+    check_status(test, "server2", master_running, "server2 should still be the master");
+    check_status(test, "server3", slave_running, "server3 should be a slave");
+
+    test.tprintf("Stop server2, expect server1 to be promoted as the master");
+    test.repl->stop_node(1);
+    test.repl->connect();
+    test.repl->replicate_from(0, 3);
+    test.repl->replicate_from(3, 0);
+    sleep(10);
+
+    check_status(test, "server1", master_running, "server1 should be the master");
+    check_status(test, "server2", down, "server2 should be down");
+    check_status(test, "server3", slave_running, "server3 should be a slave");
+
+    test.tprintf("Start server2, expect it to rejoin the cluster");
+    test.repl->start_node(1);
+    sleep(10);
+    check_status(test, "server1", master_running, "server1 should still be the master");
+    check_status(test, "server2", slave_running, "server2 should be a slave");
+    check_status(test, "server3", slave_running, "server3 should be a slave");
+
+    // Cleanup
+    is_running = false;
+    thr.join();
+    execute_query(test.repl->nodes[0], "STOP SLAVE; RESET SLAVE ALL;");
+
+    return test.global_result;
+}