upgrades.js

/*
		Copyright 2014-2015 Amazon.com, Inc. or its affiliates. All Rights Reserved.

    Licensed under the Amazon Software License (the "License"). You may not use this file except in compliance with the License. A copy of the License is located at

        http://aws.amazon.com/asl/

    or in the "license" file accompanying this file. This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, express or implied. See the License for the specific language governing permissions and limitations under the License. 
 */
var pjson = require('./package.json');
var common = require('./common');
var async = require('async');
var dynamoClient;

exports.v1_v2 = function(err, s3Info, configPre, forwardCallback) {
	if (!forwardCallback) {
		console.log("no forward callback");
	}
	// bind the current config items into the new config map
	var clusterConfig = {
		M : {}
	};
	clusterConfig.M.clusterEndpoint = configPre.clusterEndpoint;
	clusterConfig.M.clusterPort = configPre.clusterPort;
	clusterConfig.M.clusterDB = configPre.clusterDB;
	clusterConfig.M.connectUser = configPre.connectUser;
	clusterConfig.M.connectPassword = configPre.connectPassword;
	clusterConfig.M.targetTable = configPre.targetTable;
	clusterConfig.M.truncateTarget = configPre.truncateTarget;

	// update dynamo, adding the new config map as 'loadClusters' and removing the
	// old values
	var updateRequest = {
		Key : {
			s3Prefix : {
				S : s3Info.prefix
			}
		},
		TableName : configTable,
		UpdateExpression : "SET #loadCluster = :newLoadCluster, lastUpdate = :updateTime, #ver = :version "
				+ "REMOVE clusterEndpoint, clusterPort, clusterDB, connectUser, connectPassword, targetTable, truncateTarget",
		ExpressionAttributeValues : {
			":newLoadCluster" : null,
			":updateTime" : {
				N : '' + common.now()
			},
			":version" : {
				S : pjson.version
			},
			":newLoadCluster" : {
				L : [ clusterConfig ]
			}
		},
		ExpressionAttributeNames : {
			"#ver" : 'version',
			"#loadCluster" : 'loadClusters'
		},
		/*
		 * current can't be the target version, or someone else has done an upgrade
		 */
		ConditionExpression : "(attribute_not_exists(#ver) or #ver = :version) and attribute_not_exists(#loadCluster)",
		// add the ALL_NEW return values so we have the
		// get the config after update
		ReturnValues : "ALL_NEW"
	};

	dynamoClient.updateItem(updateRequest, function(err, data) {
		if (err) {
			if (err.code === conditionCheckFailed) {
				// no problem - configuration was upgraded by someone else while we were
				// running - requery and return
				var dynamoLookup = {
					Key : {
						s3Prefix : {
							S : s3Info.prefix
						}
					},
					TableName : configTable,
					ConsistentRead : true
				};

				dynamoClient.getItem(dynamoLookup, function(err, data) {
					forwardCallback(null, s3Info, data.Item);
				});
			} else {
				// unknown error - return the original configuration with the error
				forwardCallback(err, s3Info, configPre);
			}
		} else {
			// update was OK - go ahead with the new item returned by the upgrade call
			forwardCallback(null, s3Info, data.Attributes);
		}
	});
};

exports.upgradeAll = function(dynamoDB, s3Info, configPre, finalCallback) {
	dynamoClient = dynamoDB;

	// add required upgrades here
	var upgrades = [];
	upgrades[upgrades.length] = function(callback) {
		exports.v1_v2(null, s3Info, configPre, callback);
	};
	
	/* example future upgrade interface - all upgrade functions have the same spec
	 * 
	 * upgrades[upgrades.length] = function(err,s3Info,configPre,callback) {
	 * 	exports.v2_vX(null,s3Info,configPre,callback);
	 * };
	 * 
	 */

	// run all the upgrades in order
	async.waterfall(upgrades, function(err, s3Info, finalConfig) {
		if (err) {
			console.log(err);
		}

		// run the final callback
		finalCallback(err, s3Info, finalConfig);
	});
};