mongodb/jstests/hooks/run_check_repl_oplogs.js

// Runner for checkOplogs() that compares the oplog on all replica set nodes
// to ensure all nodes have the same data.
'use strict';

(function() {
var startTime = Date.now();
assert.neq(typeof db, 'undefined', 'No `db` object, is the shell connected to a mongod?');

let runCheckOnReplSet = function(db) {
    let primaryInfo = db.isMaster();

    assert(primaryInfo.ismaster,
           'shell is not connected to the primary or master node: ' + tojson(primaryInfo));

    let testFixture = new ReplSetTest(db.getMongo().host);
    testFixture.checkOplogs();
};

if (db.getMongo().isMongos()) {
    let configDB = db.getSiblingDB('config');

    // Run check on every shard.
    configDB.shards.find().forEach(shardEntry => {
        let newConn = new Mongo(shardEntry.host);
        runCheckOnReplSet(newConn.getDB('test'));
    });

    // Run check on config server.
    let cmdLineOpts = db.adminCommand({getCmdLineOpts: 1});
    let configConn = new Mongo(cmdLineOpts.parsed.sharding.configDB);
    runCheckOnReplSet(configConn.getDB('test'));
} else {
    runCheckOnReplSet(db);
}

var totalTime = Date.now() - startTime;
print('Finished consistency oplog checks of cluster in ' + totalTime + ' ms.');
})();