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/**
* Test that transactions are only allowed on primaries, and prohibited from running on secondaries.
*
* @tags: [uses_transactions]
*/
(function() {
"use strict";
// In 4.0, we allow read-only transactions on secondaries when test commands are enabled, so we
// disable them in this test, to test that transactions on secondaries will be disallowed
// for production users.
TestData.enableTestCommands = false;
TestData.roleGraphInvalidationIsFatal = false;
TestData.authenticationDatabase = "local";
const dbName = "test";
const collName = "transactions_only_allowed_on_primaries";
// Start up the replica set. We want a stable topology, so make the secondary unelectable.
const replTest = new ReplSetTest({name: collName, nodes: 2});
replTest.startSet();
let config = replTest.getReplSetConfig();
config.members[1].priority = 0;
replTest.initiate(config);
const primary = replTest.getPrimary();
const secondary = replTest.getSecondary();
// Set secondaryOk=true so that normal read commands would be allowed on the secondary.
secondary.setSecondaryOk();
// Create a test collection that we can run commands against.
const primaryDB = primary.getDB(dbName);
assert.commandWorked(primary.getDB(dbName).createCollection(collName));
assert.commandWorked(
primaryDB.runCommand({createIndexes: collName, indexes: [{name: "geo_2d", key: {geo: "2d"}}]}));
replTest.awaitLastOpCommitted();
/**
* Verify that all given commands are disallowed from starting a transaction on a secondary by
* checking that each command fails with the expected error code.
*/
function testCommands(session, commands, expectedErrorCode, readPref) {
const sessionDb = session.getDatabase(dbName);
for (let i = 0; i < commands.length; i++) {
session.startTransaction();
// Use a read preference that would normally allow read commands to run on secondaries.
if (readPref !== null) {
session.getOptions().setReadPreference(readPref);
}
const cmdObject = commands[i];
jsTestLog("Trying to start transaction on secondary with command: " + tojson(cmdObject));
assert.commandFailedWithCode(sessionDb.runCommand(cmdObject), expectedErrorCode);
// Call abort for good measure, even though the transaction should have already been
// aborted on the server.
assert.commandFailedWithCode(session.abortTransaction_forTesting(),
ErrorCodes.NotWritablePrimary);
}
}
//
// Make sure transactions are disallowed on secondaries.
//
// Initiate a session on the secondary.
const sessionOptions = {
causalConsistency: false
};
const secondarySession = secondary.getDB(dbName).getMongo().startSession(sessionOptions);
// Test read commands that are supported in transactions.
let readCommands = [
{find: collName},
{aggregate: collName, pipeline: [{$project: {_id: 1}}], cursor: {}},
{distinct: collName, key: "_id"},
];
jsTestLog("Testing read commands.");
// Make sure read commands can not start transactions with any supported read preference.
testCommands(secondarySession, readCommands, ErrorCodes.NotWritablePrimary, "secondary");
testCommands(secondarySession, readCommands, ErrorCodes.NotWritablePrimary, "secondaryPreferred");
testCommands(secondarySession, readCommands, ErrorCodes.NotWritablePrimary, "primaryPreferred");
testCommands(secondarySession, readCommands, ErrorCodes.NotWritablePrimary, null);
// Test one write command. Normal write commands should already be
// disallowed on secondaries so we don't test them exhaustively here.
let writeCommands = [{insert: collName, documents: [{_id: 0}]}];
jsTestLog("Testing write commands.");
testCommands(secondarySession, writeCommands, ErrorCodes.NotWritablePrimary, "secondary");
secondarySession.endSession();
//
// Make sure transactions are allowed on primaries with any valid read preference.
//
const primarySession = primary.getDB(dbName).getMongo().startSession(sessionOptions);
const primarySessionDb = primarySession.getDatabase(dbName);
primarySession.startTransaction();
assert.commandWorked(
primarySessionDb.runCommand({find: collName, $readPreference: {mode: "primary"}}));
assert.commandWorked(primarySession.commitTransaction_forTesting());
primarySession.startTransaction();
assert.commandWorked(
primarySessionDb.runCommand({find: collName, $readPreference: {mode: "primaryPreferred"}}));
assert.commandWorked(primarySession.commitTransaction_forTesting());
primarySession.startTransaction();
assert.commandWorked(
primarySessionDb.runCommand({find: collName, $readPreference: {mode: "secondaryPreferred"}}));
assert.commandWorked(primarySession.commitTransaction_forTesting());
primarySession.startTransaction();
assert.commandWorked(
primarySessionDb.runCommand({find: collName, $readPreference: {mode: "nearest"}}));
assert.commandWorked(primarySession.commitTransaction_forTesting());
primarySession.endSession();
replTest.stopSet();
}());
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