Merge pull request #233 from nitrictech/fix/aws-schedules

fix: fix schedule deployment to AWS

Author: jyecusch

packages/plugins/aws/src/resources/schedule.test.ts

@@ -0,0 +1,103 @@
+// Copyright 2021, Nitric Technologies Pty Ltd.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+import { cronToAwsCron } from './schedule';
+
+describe('Cron Expression Conversion', () => {
+	describe('Given an expression with more than 5 values', () => {
+		const exp = '*/1 * * * ? *';
+
+		it('Should throw an error', () => {
+			expect(() => {
+				cronToAwsCron(exp);
+			}).toThrow();
+		});
+	});
+
+	describe('Given a valid cron expression', () => {
+		const exp = '*/1 * * * *';
+
+		describe('When converting the expression', () => {
+			let awsExpValues: string[] = [];
+			beforeAll(() => {
+				// Expected result = '0/1 * * * ? *'
+				awsExpValues = cronToAwsCron(exp).split(' ');
+			});
+
+			it('Should replace the * with 0 for "every x unit" style values', () => {
+				expect(awsExpValues[0]).toEqual('0/1');
+			});
+
+			it('Should replace * in Day of Week with ? if DOW and DOM are both *', () => {
+				expect(awsExpValues[4]).toEqual('?');
+			});
+
+			it('Should output an expression with year added as a *', () => {
+				expect(awsExpValues.length).toEqual(6);
+				expect(awsExpValues[5]).toEqual('*');
+			});
+		});
+	});
+
+	describe('Given a valid cron with a Day of Week value between 0-6', () => {
+		const exp = '*/1 * * * 3';
+
+		describe('When converting the expression', () => {
+			let awsExpValues: string[] = [];
+			beforeAll(() => {
+				// Expected result = '0/1 * ? * 3 *'
+				awsExpValues = cronToAwsCron(exp).split(' ');
+			});
+
+			it('increment the value by 1', () => {
+				expect(awsExpValues[4]).toEqual('4');
+			});
+
+			it('Should replace * in Day of Month with ?', () => {
+				expect(awsExpValues[2]).toEqual('?');
+			});
+		});
+	});
+
+	describe('Given a valid cron with a Day of Week value of 7 (Sunday)', () => {
+		const exp = '*/1 * * * 7';
+
+		describe('When converting the expression', () => {
+			let awsExpValues: string[] = [];
+			beforeAll(() => {
+				// Expected result = '0/1 * ? * 1 *'
+				awsExpValues = cronToAwsCron(exp).split(' ');
+			});
+
+			it('Should set the value to 1 (Sunday)', () => {
+				expect(awsExpValues[4]).toEqual('1');
+			});
+		});
+	});
+
+	describe('Given a valid cron with a Day of Week value range', () => {
+		const exp = '*/1 * * * 1-3';
+
+		describe('When converting the expression', () => {
+			let awsExpValues: string[] = [];
+			beforeAll(() => {
+				// Expected result = '0/1 * ? * 2-4 *'
+				awsExpValues = cronToAwsCron(exp).split(' ');
+			});
+
+			it('Should increment both values by 1', () => {
+				expect(awsExpValues[4]).toEqual('2-4');
+			});
+		});
+	});
+});

packages/plugins/aws/src/resources/schedule.ts

@@ -21,6 +21,77 @@ interface NitricScheduleEventBridgeArgs {
 	topics: NitricSnsTopic[];
 }
 
+/**
+ * Converts a standard Crontab style cron expression to an AWS specific format.
+ *
+ * AWS appears to use a variation of the Quartz "Unix-like" Cron Expression Format.
+ * Notable changes include:
+ * - Removing the 'seconds' value (seconds are not supported)
+ * - Making the 'year' value mandatory
+ * - Providing a value for both Day of Month and Day of Year is not supported.
+ *
+ * Quartz CronExpression Docs:
+ * https://www.javadoc.io/doc/org.quartz-scheduler/quartz/1.8.2/org/quartz/CronExpression.html
+ *
+ * AWS Specific CronExpressions Doc:
+ * https://docs.aws.amazon.com/AmazonCloudWatch/latest/events/ScheduledEvents.html#CronExpressions
+ *
+ * Crontab Expression Docs:
+ * https://man7.org/linux/man-pages/man5/crontab.5.html
+ *
+ * @param crontab the crontab style cron expression string
+ * @returns the input cron expression returned in the AWS specific format
+ */
+export const cronToAwsCron = (crontab: string): string => {
+	let parts = crontab.split(' ');
+	if (parts.length !== 5) {
+		throw new Error(`Invalid Expression. Expected 5 expression values, received ${parts.length}`);
+	}
+
+	// Replace */x (i.e. "every x minutes") style inputs to the AWS equivalent
+	// AWS uses 0 instead of * for these expressions
+	parts = parts.map((part) => part.replace(/^\*(?=\/.*)/g, '0'));
+
+	// Only day of week or day of month can be set with AWS, the other must be a ? char
+	// See: https://docs.aws.amazon.com/AmazonCloudWatch/latest/events/ScheduledEvents.html#CronExpressions - Restrictions
+	const DAY_OF_MONTH = 2;
+	const DAY_OF_WEEK = 4;
+	if (parts[DAY_OF_WEEK] === '*') {
+		parts[DAY_OF_WEEK] = '?';
+	} else {
+		if (parts[DAY_OF_MONTH] !== '*') {
+			// TODO: We can support both in future by creating two EventRules - one for DOW, another for DOM.
+			throw new Error('Invalid Expression. Day of Month and Day of Week expression component cannot both be set.');
+		}
+		parts[DAY_OF_MONTH] = '?';
+	}
+
+	// We also need to adjust the Day of Week value
+	// crontab uses 0-7 (0 or 7 is Sunday)
+	// AWS uses 1-7 (Sunday-Saturday)
+	parts[DAY_OF_WEEK] = parts[DAY_OF_WEEK].split('')
+		.map((char) => {
+			let num = parseInt(char);
+
+			if (!isNaN(num)) {
+				// Check for standard 0-6 day range and increment
+				if (num >= 0 && num <= 6) {
+					return num + 1;
+				} else {
+					// otherwise default to Sunday
+					return 1;
+				}
+			} else {
+				return char;
+			}
+		})
+		.join('');
+
+	// Add the year component, this doesn't exist in crontab expressions, so we default it to *
+	parts = [...parts, '*'];
+	return parts.join(' ');
+};
+
 /**
  * Nitric EventBridge based Schedule
  */
@@ -40,13 +111,20 @@ export class NitricScheduleEventBridge extends pulumi.ComponentResource {
 
 		this.name = schedule.name;
 
+		let awsCronValue = '';
+		try {
+			awsCronValue = cronToAwsCron(schedule.expression?.replace(/['"]+/g, ''));
+		} catch (error) {
+			throw new Error(`Failed to process expression for schedule ${this.name}. Details: ${(error as Error).message}`);
+		}
+
 		if (topic) {
 			const rule = new aws.cloudwatch.EventRule(
 				`${schedule.name}Schedule`,
 				{
 					description: `Nitric schedule trigger for ${schedule.name}`,
 					name: schedule.name,
-					scheduleExpression: `cron(${schedule.expression?.replace(/['"]+/g, '')})`,
+					scheduleExpression: `cron(${awsCronValue})`,
 				},
 				defaultResourceOptions,
 			);
@@ -59,6 +137,35 @@ export class NitricScheduleEventBridge extends pulumi.ComponentResource {
 				},
 				defaultResourceOptions,
 			);
+
+			const snsTopicSchedulePolicy = topic.sns.arn.apply((arn) =>
+				aws.iam.getPolicyDocument({
+					// TODO: According to the docs, 'conditions' are not supported for a policy involving EventBridge
+					// See: https://docs.aws.amazon.com/eventbridge/latest/userguide/eb-use-resource-based.html#eb-sns-permissions
+					//  "You can't use of Condition blocks in Amazon SNS topic policies for EventBridge."
+					// This means any EventBridge rule will be able to publish to this topic.
+					policyId: '__default_policy_ID',
+					statements: [
+						{
+							sid: '__default_statement_ID',
+							effect: 'Allow',
+							actions: ['SNS:Publish'],
+							principals: [
+								{
+									type: 'Service',
+									identifiers: ['events.amazonaws.com'],
+								},
+							],
+							resources: [arn],
+						},
+					],
+				}),
+			);
+
+			new aws.sns.TopicPolicy(`${schedule.name}Target${topic.name}Policy`, {
+				arn: topic.sns.arn,
+				policy: snsTopicSchedulePolicy.apply((snsTopicPolicy) => snsTopicPolicy.json),
+			});
 		}
 
 		this.registerOutputs({