jstests/replsets/priority_takeover_one_node_higher_priority.js


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// Priority (1 member with non-default priority).
// 3-node replica set - one arbiter and two electable nodes with different priorities.
// Wait for replica set to stabilize with higher priority node as primary.
// Step down high priority node. Wait for the lower priority electable node to become primary.
// Eventually high priority node will run a priority takeover election to become primary.
(function() {
    'use strict';
    load('jstests/replsets/rslib.js');
    load('jstests/replsets/libs/election_metrics.js');

    var name = 'priority_takeover_one_node_higher_priority';
    var replSet = new ReplSetTest({
        name: name,
        nodes: [
            {rsConfig: {priority: 3}},
            {},
            {rsConfig: {arbiterOnly: true}},
        ]
    });
    replSet.startSet();
    replSet.initiate();

    replSet.waitForState(replSet.nodes[0], ReplSetTest.State.PRIMARY);
    var primary = replSet.getPrimary();

    const initialPrimaryStatus = assert.commandWorked(primary.adminCommand({serverStatus: 1}));

    replSet.awaitSecondaryNodes();
    replSet.awaitReplication();

    // Primary should step down long enough for election to occur on secondary.
    var config = assert.commandWorked(primary.adminCommand({replSetGetConfig: 1})).config;
    assert.commandWorked(primary.adminCommand({replSetStepDown: replSet.kDefaultTimeoutMS / 1000}));

    // Step down primary and wait for node 1 to be promoted to primary.
    replSet.waitForState(replSet.nodes[1], ReplSetTest.State.PRIMARY);

    // Unfreeze node 0 so it can seek election.
    assert.commandWorked(primary.adminCommand({replSetFreeze: 0}));

    // Eventually node 0 will stand for election again because it has a higher priorty.
    replSet.waitForState(replSet.nodes[0], ReplSetTest.State.PRIMARY);

    // Check that both the 'called' and 'successful' fields of the 'priorityTakeover' election
    // reason counter have been incremented in serverStatus.
    const newPrimaryStatus = assert.commandWorked(primary.adminCommand({serverStatus: 1}));
    verifyServerStatusElectionReasonCounterChange(initialPrimaryStatus.electionMetrics,
                                                  newPrimaryStatus.electionMetrics,
                                                  "priorityTakeover",
                                                  1);

    replSet.stopSet();
})();