entry.swift

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
//
// snippet-start:[swift.glue.scenario]
// An example that shows how to use the AWS SDK for Swift to demonstrate
// creating and using crawlers and jobs using AWS Glue.
//
// 0. Upload the Python job script to Amazon S3 so it can be used when
//    calling `startJobRun()` later.
// 1. Create a crawler, pass it the IAM role and the URL of the public Amazon
//    S3 bucket that contains the source data:
//    s3://crawler-public-us-east-1/flight/2016/csv.
// 2. Start the crawler. This takes time, so after starting it, use a loop
//    that calls `getCrawler()` until the state is "READY".
// 3. Get the database created by the crawler, and the tables in the
//    database. Display them to the user.
// 4. Create a job. Pass it the IAM role and the URL to a Python ETL script
//    previously uploaded to the user's S3 bucket.
// 5. Start a job run, passing the following custom arguments. These are
//    expected by the ETL script, so must exactly match.
//    * `--input_database: <name of the database created by the crawler>`
//    * `--input_table: <name of the table created by the crawler>`
//    * `--output_bucket_url: <URL to the scaffold bucket created for the
//      user>`
// 6. Loop and get the job run until it returns one of the following states:
//    "SUCCEEDED", "STOPPED", "FAILED", or "TIMEOUT".
// 7. Output data is stored in a group of files in the user's S3 bucket.
//    Either direct the user to their location or download a file and display
//    the results inline.
// 8. List the jobs for the user's account.
// 9. Get job run details for a job run.
// 10. Delete the demo job.
// 11. Delete the database and tables created by the example.
// 12. Delete the crawler created by the example.

import ArgumentParser
import AWSS3
import Foundation
import Smithy

// snippet-start:[swift.glue.import]
import AWSClientRuntime
import AWSGlue
// snippet-end:[swift.glue.import]

struct ExampleCommand: ParsableCommand {
    @Option(help: "The AWS IAM role to use for AWS Glue calls.")
    var role: String

    @Option(help: "The Amazon S3 bucket to use for this example.")
    var bucket: String

    @Option(help: "The Amazon S3 URL of the data to crawl.")
    var s3url: String = "s3://crawler-public-us-east-1/flight/2016/csv"

    @Option(help: "The Python script to run as a job with AWS Glue.")
    var script: String = "./flight_etl_job_script.py"

    @Option(help: "The AWS Region to run AWS API calls in.")
    var awsRegion = "us-east-1"

    @Option(help: "A prefix string to use when naming tables.")
    var tablePrefix = "swift-glue-basics-table"

    @Option(
        help: ArgumentHelp("The level of logging for the Swift SDK to perform."),
        completion: .list([
            "critical",
            "debug",
            "error",
            "info",
            "notice",
            "trace",
            "warning"
        ])
    )
    var logLevel: String = "error"

    static var configuration = CommandConfiguration(
        commandName: "glue-scenario",
        abstract: """
        Demonstrates various features of AWS Glue.
        """,
        discussion: """
        An example showing how to use AWS Glue to create, run, and monitor
        crawlers and jobs.
        """
    )

    /// Generate and return a unique file name that begins with the specified
    /// string.
    ///
    /// - Parameters:
    ///   - prefix: Text to use at the beginning of the returned name.
    ///
    /// - Returns: A string containing a unique filename that begins with the
    ///   specified `prefix`.
    ///
    /// The returned name uses a random number between 1 million and 1 billion to
    /// provide reasonable certainty of uniqueness for the purposes of this
    /// example.
    func tempName(prefix: String) -> String {
        return "\(prefix)-\(Int.random(in: 1000000..<1000000000))"
    }

    /// Upload a file to an Amazon S3 bucket.
    /// 
    /// - Parameters:
    ///   - s3Client: The S3 client to use when uploading the file.
    ///   - path: The local path of the source file to upload.
    ///   - toBucket: The name of the S3 bucket into which to upload the file.
    ///   - key: The key (name) to give the file in the S3 bucket.
    ///
    /// - Returns: `true` if the file is uploaded successfully, otherwise `false`.
    func uploadFile(s3Client: S3Client, path: String, toBucket: String, key: String) async -> Bool {
        do {
            let fileData: Data = try Data(contentsOf: URL(fileURLWithPath: path))
            let dataStream = ByteStream.data(fileData)
            _ = try await s3Client.putObject(
                input: PutObjectInput(
                    body: dataStream,
                    bucket: toBucket,
                    key: key
                )
            )
        } catch {
            print("*** An unexpected error occurred uploading the script to the Amazon S3 bucket \"\(bucket)\".")
            return false
        }

        return true
    }

    // snippet-start:[swift.glue.CreateCrawler]
    /// Create a new AWS Glue crawler.
    /// 
    /// - Parameters:
    ///   - glueClient: An AWS Glue client to use for the crawler.
    ///   - crawlerName: A name for the new crawler.
    ///   - iamRole: The name of an Amazon IAM role for the crawler to use.
    ///   - s3Path: The path of an Amazon S3 folder to use as a target location.
    ///   - cronSchedule: A `cron` schedule indicating when to run the crawler.
    ///   - databaseName: The name of an AWS Glue database to operate on.
    ///
    /// - Returns: `true` if the crawler is created successfully, otherwise `false`.
    func createCrawler(glueClient: GlueClient, crawlerName: String, iamRole: String,
                       s3Path: String, cronSchedule: String, databaseName: String) async -> Bool {
        let s3Target = GlueClientTypes.S3Target(path: s3url)
        let targetList = GlueClientTypes.CrawlerTargets(s3Targets: [s3Target])

        do {
            _ = try await glueClient.createCrawler(
                input: CreateCrawlerInput(
                    databaseName: databaseName,
                    description: "Created by the AWS SDK for Swift Scenario Example for AWS Glue.",
                    name: crawlerName,
                    role: iamRole,
                    schedule: cronSchedule,
                    tablePrefix: tablePrefix,
                    targets: targetList
                )
            )
        } catch _ as AlreadyExistsException {
            print("*** A crawler named \"\(crawlerName)\" already exists.")
            return false
        } catch _ as OperationTimeoutException {
            print("*** The attempt to create the AWS Glue crawler timed out.")
            return false
        } catch {
            print("*** An unexpected error occurred creating the AWS Glue crawler: \(error.localizedDescription)")
            return false
        }

        return true
    }
    // snippet-end:[swift.glue.CreateCrawler]

    // snippet-start:[swift.glue.DeleteCrawler]
    /// Delete an AWS Glue crawler.
    /// 
    /// - Parameters:
    ///   - glueClient: The AWS Glue client to use.
    ///   - name: The name of the crawler to delete.
    ///
    /// - Returns: `true` if successful, otherwise `false`.
    func deleteCrawler(glueClient: GlueClient, name: String) async -> Bool {
        do {
            _ = try await glueClient.deleteCrawler(
                input: DeleteCrawlerInput(name: name)
            )
        } catch {
            return false
        }
        return true
    }
    // snippet-end:[swift.glue.DeleteCrawler]

    // snippet-start:[swift.glue.StartCrawler]
    /// Start running an AWS Glue crawler.
    /// 
    /// - Parameters:
    ///   - glueClient: The AWS Glue client to use when starting the crawler.
    ///   - name: The name of the crawler to start running.
    ///
    /// - Returns: `true` if the crawler is started successfully, otherwise `false`.
    func startCrawler(glueClient: GlueClient, name: String) async -> Bool {
        do {
            _ = try await glueClient.startCrawler(
                input: StartCrawlerInput(name: name)
            )
        } catch {
            print("*** An unexpected error occurred starting the crawler.")
            return false
        }

        return true
    }
    // snippet-end:[swift.glue.StartCrawler]

    // snippet-start:[swift.glue.GetCrawler]
    /// Get the state of the specified AWS Glue crawler.
    /// 
    /// - Parameters:
    ///   - glueClient: The AWS Glue client to use.
    ///   - name: The name of the crawler whose state should be returned.
    ///
    /// - Returns: A `GlueClientTypes.CrawlerState` value describing the
    ///   state of the crawler.
    func getCrawlerState(glueClient: GlueClient, name: String) async -> GlueClientTypes.CrawlerState {
        do {
            let output = try await glueClient.getCrawler(
                input: GetCrawlerInput(name: name)
            )

            // If the crawler or its state is `nil`, report that the crawler
            // is stopping. This may not be what you want for your
            // application but it works for this one!
            
            guard let crawler = output.crawler else {
                return GlueClientTypes.CrawlerState.stopping
            }
            guard let state = crawler.state else {
                return GlueClientTypes.CrawlerState.stopping            
            }
            return state
        } catch {
            return GlueClientTypes.CrawlerState.stopping
        }
    }
    // snippet-end:[swift.glue.GetCrawler]

    // snippet-start:[swift.glue.getCrawlerState]
    /// Wait until the specified crawler is ready to run.
    /// 
    /// - Parameters:
    ///   - glueClient: The AWS Glue client to use.
    ///   - name: The name of the crawler to wait for.
    ///
    /// - Returns: `true` if the crawler is ready, `false` if the client is
    ///   stopping (and will therefore never be ready).
    func waitUntilCrawlerReady(glueClient: GlueClient, name: String) async -> Bool {
        while true {
            let state = await getCrawlerState(glueClient: glueClient, name: name)

            if state == .ready {
                return true
            } else if state == .stopping {
                return false
            }
            Thread.sleep(forTimeInterval: 4)
        }
    }
    // snippet-end:[swift.glue.getCrawlerState]

    // snippet-start:[swift.glue.CreateJob]
    /// Create a new AWS Glue job.
    /// 
    /// - Parameters:
    ///   - glueClient: The AWS Glue client to use.
    ///   - jobName: The name to give the new job.
    ///   - role: The IAM role for the job to use when accessing AWS services.
    ///   - scriptLocation: The AWS S3 URI of the script to be run by the job.
    /// 
    /// - Returns: `true` if the job is created successfully, otherwise `false`.
    func createJob(glueClient: GlueClient, name jobName: String, role: String,
                   scriptLocation: String) async -> Bool {
        let command = GlueClientTypes.JobCommand(
            name: "glueetl",
            pythonVersion: "3",
            scriptLocation: scriptLocation
        )

        do {
            _ = try await glueClient.createJob(
                input: CreateJobInput(
                    command: command,
                    description: "Created by the AWS SDK for Swift Glue basic scenario example.",
                    glueVersion: "3.0",
                    name: jobName,
                    numberOfWorkers: 10,
                    role: role,
                    workerType: .g1x
                )
            )
        } catch {
            return false
        }
        return true
    }
    // snippet-end:[swift.glue.CreateJob]

    // snippet-start:[swift.glue.ListJobs]
    /// Return a list of the AWS Glue jobs listed on the user's account.
    /// 
    /// - Parameters:
    ///   - glueClient: The AWS Glue client to use.
    ///   - maxJobs: The maximum number of jobs to return (default: 100).
    /// 
    /// - Returns: An array of strings listing the names of all available AWS
    ///   Glue jobs.
    func listJobs(glueClient: GlueClient, maxJobs: Int = 100) async -> [String] {
        var jobList: [String] = []
        var nextToken: String?

        repeat {
            do {
                let output = try await glueClient.listJobs(
                    input: ListJobsInput(
                        maxResults: maxJobs,
                        nextToken: nextToken
                    )
                )

                guard let jobs = output.jobNames else {
                    return jobList
                }

                jobList = jobList + jobs
                nextToken = output.nextToken
            } catch {
                return jobList
            }
        } while (nextToken != nil)

        return jobList
    }
    // snippet-end:[swift.glue.ListJobs]

    // snippet-start:[swift.glue.DeleteJob]
    /// Delete an AWS Glue job.
    /// 
    /// - Parameters:
    ///   - glueClient: The AWS Glue client to use.
    ///   - jobName: The name of the job to delete.
    ///
    /// - Returns: `true` if the job is successfully deleted, otherwise `false`.
    func deleteJob(glueClient: GlueClient, name jobName: String) async -> Bool {
        do {
            _ = try await glueClient.deleteJob(
                input: DeleteJobInput(jobName: jobName)
            )
        } catch {
            return false
        }
        return true
    }
    // snippet-end:[swift.glue.DeleteJob]

    // snippet-start:[swift.glue.CreateDatabase]
    /// Create an AWS Glue database.
    /// 
    /// - Parameters:
    ///   - glueClient: The AWS Glue client to use.
    ///   - databaseName: The name to give the new database.
    ///   - location: The URL of the source data to use with AWS Glue.
    ///
    /// - Returns: `true` if the database is created successfully, otherwise `false`.
    func createDatabase(glueClient: GlueClient, name databaseName: String, location: String) async -> Bool {
        let databaseInput = GlueClientTypes.DatabaseInput(
            description: "Created by the AWS SDK for Swift Glue basic scenario example.",
            locationUri: location,
            name: databaseName
        )

        do {
            _ = try await glueClient.createDatabase(
                input: CreateDatabaseInput(
                    databaseInput: databaseInput
                )
            )
        } catch {
            return false
        }

        return true
    }
    // snippet-end:[swift.glue.CreateDatabase]

    // snippet-start:[swift.glue.GetDatabase]
    /// Get the AWS Glue database with the specified name.
    ///
    /// - Parameters:
    ///   - glueClient: The AWS Glue client to use.
    ///   - name: The name of the database to return.
    ///
    /// - Returns: The `GlueClientTypes.Database` object describing the
    ///   specified database, or `nil` if an error occurs or the database
    ///   isn't found.
    func getDatabase(glueClient: GlueClient, name: String) async -> GlueClientTypes.Database? {
        do {
            let output = try await glueClient.getDatabase(
                input: GetDatabaseInput(name: name)
            )

            return output.database
        } catch {
            return nil
        }
    }
    // snippet-end:[swift.glue.GetDatabase]

    // snippet-start:[swift.glue.GetTables]
    /// Returns a list of the tables in the specified database.
    /// 
    /// - Parameters:
    ///   - glueClient: The AWS Glue client to use.
    ///   - databaseName: The name of the database whose tables are to be
    ///     returned.
    ///
    /// - Returns: An array of `GlueClientTypes.Table` objects, each
    ///   describing one table in the named database. An empty array indicates
    ///   that there are either no tables in the database, or an error
    ///   occurred before any tables could be found.
    func getTablesInDatabase(glueClient: GlueClient, databaseName: String) async -> [GlueClientTypes.Table] {
        var tables: [GlueClientTypes.Table] = []
        var nextToken: String?

        repeat {
            do {
                let output = try await glueClient.getTables(
                    input: GetTablesInput(
                        databaseName: databaseName,
                        nextToken: nextToken
                    )
                )

                guard let tableList = output.tableList else {
                    return tables
                }

                tables = tables + tableList
                nextToken = output.nextToken
            } catch {
                return tables
            }
        } while nextToken != nil

        return tables
    }
    // snippet-end:[swift.glue.GetTables]

    // snippet-start:[swift.glue.BatchDeleteTable]
    // snippet-start:[swift.glue.DeleteDatabase]
    /// Delete the specified database.
    /// 
    /// - Parameters:
    ///   - glueClient: The AWS Glue client to use.
    ///   - databaseName: The name of the database to delete.
    ///   - deleteTables: A Bool indicating whether or not to delete the
    ///     tables in the database before attempting to delete the database.
    /// 
    /// - Returns: `true` if the database (and optionally its tables) are
    ///   deleted, otherwise `false`.
    func deleteDatabase(glueClient: GlueClient, name databaseName: String,
                        withTables deleteTables: Bool = false) async -> Bool {
        if deleteTables {
            var tableNames: [String] = []

            // Get a list of the names of all of the tables in the database.

            let tableList = await self.getTablesInDatabase(glueClient: glueClient, databaseName: databaseName)
            for table in tableList {
                guard let name = table.name else {
                    continue
                }
                tableNames.append(name)
            }

            // Delete the tables.

            do {
                _ = try await glueClient.batchDeleteTable(
                    input: BatchDeleteTableInput(
                        databaseName: databaseName,
                        tablesToDelete: tableNames
                    )
                )
            } catch {
                print("*** Unable to delete the tables.")
            }
            return true
        }

        // Delete the database itself.

        do {
            _ = try await glueClient.deleteDatabase(
                input: DeleteDatabaseInput(name: databaseName)
            )
        } catch {
            print("*** Unable to delete the database.")
        }
        return true
    }
    // snippet-end:[swift.glue.DeleteDatabase]
    // snippet-end:[swift.glue.BatchDeleteTable]

    // snippet-start:[swift.glue.StartJobRun]
    /// Start an AWS Glue job run.
    /// 
    /// - Parameters:
    ///   - glueClient: The AWS Glue client to use.
    ///   - jobName: The name of the job to run.
    ///   - databaseName: The name of the AWS Glue database to run the job against.
    ///   - tableName: The name of the table in the database to run the job against.
    ///   - outputURL: The AWS S3 URI of the bucket location into which to
    ///     write the resulting output.
    ///
    /// - Returns: `true` if the job run is started successfully, otherwise `false`.
    func startJobRun(glueClient: GlueClient, name jobName: String, databaseName: String,
                     tableName: String, outputURL: String) async -> String? {
        do {
            let output = try await glueClient.startJobRun(
                input: StartJobRunInput(
                    arguments: [
                        "--input_database": databaseName,
                        "--input_table": tableName,
                        "--output_bucket_url": outputURL
                    ],
                    jobName: jobName,
                    numberOfWorkers: 10,
                    workerType: .g1x
                )
            )

            guard let id = output.jobRunId else {
                return nil
            }

            return id
        } catch {
            return nil
        }
    }
    // snippet-end:[swift.glue.StartJobRun]

    // snippet-start:[swift.glue.GetJobRun]
    /// Get information about a specific AWS Glue job run.
    /// 
    /// - Parameters:
    ///   - glueClient: The AWS Glue client to use.
    ///   - jobName: The name of the job to return job run data for.
    ///   - id: The run ID of the specific job run to return.
    ///
    /// - Returns: A `GlueClientTypes.JobRun` object describing the state of
    ///   the job run, or `nil` if an error occurs.
    func getJobRun(glueClient: GlueClient, name jobName: String, id: String) async -> GlueClientTypes.JobRun? {
        do {
            let output = try await glueClient.getJobRun(
                input: GetJobRunInput(
                    jobName: jobName,
                    runId: id
                )
            )

            return output.jobRun
        } catch {
            return nil
        }
    }
    // snippet-end:[swift.glue.GetJobRun]

    /// Called by ``main()`` to run the bulk of the example.
    func runAsync() async throws {
        // A name to give the Python script upon upload to the Amazon S3
        // bucket.
        let scriptName = "jobscript.py"

        // Schedule string in `cron` format, as described here:
        // https://docs.aws.amazon.com/glue/latest/dg/monitor-data-warehouse-schedule.html
        let cron = "cron(15 12 * * ? *)"

        let glueConfig = try await GlueClient.GlueClientConfiguration(region: awsRegion)
        let glueClient = GlueClient(config: glueConfig)

        let s3Config = try await S3Client.S3ClientConfiguration(region: awsRegion)
        let s3Client = S3Client(config: s3Config)

        // Create random names for things that need them.

        let crawlerName = tempName(prefix: "swift-glue-basics-crawler")
        let databaseName = tempName(prefix: "swift-glue-basics-db")

        // Create a name for the AWS Glue job.

        let jobName = tempName(prefix: "scenario-job")

        // The URL of the Python script on S3.

        let scriptURL = "s3://\(bucket)/\(scriptName)"

        print("Welcome to the AWS SDK for Swift basic scenario for AWS Glue!")

        //=====================================================================
        // 0. Upload the Python script to the target bucket so it's available
        //    for use by the Amazon Glue service.
        //=====================================================================

        print("Uploading the Python script: \(script) as key \(scriptName)")
        print("Destination bucket: \(bucket)")
        if !(await uploadFile(s3Client: s3Client, path: script, toBucket: bucket, key: scriptName)) {
            return
        }

        //=====================================================================
        // 1. Create the database and crawler using the randomized names
        //    generated previously.
        //=====================================================================

        print("Creating database \"\(databaseName)\"...")
        if !(await createDatabase(glueClient: glueClient, name: databaseName, location: s3url)) {
            print("*** Unable to create the database.")
            return
        }

        print("Creating crawler \"\(crawlerName)\"...")
        if !(await createCrawler(glueClient: glueClient, crawlerName: crawlerName,
                                 iamRole: role, s3Path: s3url, cronSchedule: cron,
                                 databaseName: databaseName)) {
            return
        }

        //=====================================================================
        // 2. Start the crawler, then wait for it to be ready.
        //=====================================================================

        print("Starting the crawler and waiting until it's ready...")
        if !(await startCrawler(glueClient: glueClient, name: crawlerName)) {
            _ = await deleteCrawler(glueClient: glueClient, name: crawlerName)
            return
        }

        if !(await waitUntilCrawlerReady(glueClient: glueClient, name: crawlerName)) {
            _ = await deleteCrawler(glueClient: glueClient, name: crawlerName)
        }

        //=====================================================================
        // 3. Get the database and table created by the crawler.
        //=====================================================================

        print("Getting the crawler's database...")
        let database = await getDatabase(glueClient: glueClient, name: databaseName)
        let tableList = await getTablesInDatabase(glueClient: glueClient, databaseName: databaseName)

        print("Found \(tableList.count) table(s):")
        for table in tableList {
            print("  \(table.name ?? "<unnamed>")")
        }

        if tableList.count != 1 {
            print("*** Incorrect number of tables found. There should only be one.")
            _ = await deleteDatabase(glueClient: glueClient, name: databaseName, withTables: true)
            _ = await deleteCrawler(glueClient: glueClient, name: crawlerName)
            return
        }

        guard let tableName = tableList[0].name else {
            print("*** Table is unnamed.")
            _ = await deleteDatabase(glueClient: glueClient, name: databaseName, withTables: true)
            _ = await deleteCrawler(glueClient: glueClient, name: crawlerName)
            return
        }

        //=====================================================================
        // 4. Create a job.
        //=====================================================================

        print("Creating a job...")
        if !(await createJob(glueClient: glueClient, name: jobName, role: role,
                             scriptLocation: scriptURL)) {
            _ = await deleteDatabase(glueClient: glueClient, name: databaseName, withTables: true)
            _ = await deleteCrawler(glueClient: glueClient, name: crawlerName)
            return
        }

        //=====================================================================
        // 5. Start a job run.
        //=====================================================================

        print("Starting the job...")

        // Construct the Amazon S3 URL for the job run's output. This is in
        // the bucket specified on the command line, with a folder name that's
        // unique for this job run.

        let timeStamp = Date().timeIntervalSince1970
        let jobPath = "\(jobName)-\(Int(timeStamp))"
        let outputURL = "s3://\(bucket)/\(jobPath)"

        // Start the job run.

        let jobRunID = await startJobRun(glueClient: glueClient, name: jobName,
                                         databaseName: databaseName,
                                         tableName: tableName,
                                         outputURL: outputURL)

        guard let jobRunID else {
            print("*** Job run ID is invalid.")
            _ = await deleteJob(glueClient: glueClient, name: jobName)
            _ = await deleteDatabase(glueClient: glueClient, name: databaseName, withTables: true)
            _ = await deleteCrawler(glueClient: glueClient, name: crawlerName)
            return
        }

        //=====================================================================
        // 6. Wait for the job run to indicate that the run is complete.
        //=====================================================================

        print("Waiting for job run to end...")

        var jobRunFinished = false
        var jobRunState: GlueClientTypes.JobRunState

        repeat {
            let jobRun = await getJobRun(glueClient: glueClient, name: jobName, id: jobRunID)
            guard let jobRun else {
                print("*** Unable to get the job run.")
                _ = await deleteJob(glueClient: glueClient, name: jobName)
                _ = await deleteDatabase(glueClient: glueClient, name: databaseName, withTables: true)
                _ = await deleteCrawler(glueClient: glueClient, name: crawlerName)
                return
            }
            jobRunState = jobRun.jobRunState ?? .failed

            //=====================================================================
            // 7. Output where to find the data if the job run was successful.
            //    If the job run failed for any reason, output an appropriate
            //    error message.
            //=====================================================================

            switch jobRunState {
                case .succeeded:
                    print("Job run succeeded. JSON files are in the Amazon S3 path:")
                    print("    \(outputURL)")
                    jobRunFinished = true
                case .stopped:
                    jobRunFinished = true
                case .error:
                    print("*** Error: Job run ended in an error. \(jobRun.errorMessage ?? "")")
                    jobRunFinished = true
                case .failed:
                    print("*** Error: Job run failed. \(jobRun.errorMessage ?? "")")
                    jobRunFinished = true
                case .timeout:
                    print("*** Warning: Job run timed out.")
                    jobRunFinished = true
                default:
                    Thread.sleep(forTimeInterval: 0.25)
            }
        } while jobRunFinished != true

        //=====================================================================
        // 8. List the jobs for the user's account.
        //=====================================================================

        print("\nThe account has the following jobs:")
        let jobs = await listJobs(glueClient: glueClient)

        if jobs.count == 0 {
            print("    <no jobs found>")
        } else {
            for job in jobs {
                print("    \(job)")
            }
        }

        //=====================================================================
        // 9. Get the job run details for a job run.
        //=====================================================================

        print("Information about the job run:")
        let jobRun = await getJobRun(glueClient: glueClient, name: jobName, id: jobRunID)

        guard let jobRun else {
            print("*** Unable to retrieve the job run.")
            _ = await deleteJob(glueClient: glueClient, name: jobName)
            _ = await deleteDatabase(glueClient: glueClient, name: databaseName, withTables: true)
            _ = await deleteCrawler(glueClient: glueClient, name: crawlerName)
            return
        }

        let startDate = jobRun.startedOn ?? Date(timeIntervalSince1970: 0)
        let endDate = jobRun.completedOn ?? Date(timeIntervalSince1970: 0)
        let dateFormatter: DateFormatter = DateFormatter()
        dateFormatter.dateStyle = .long
        dateFormatter.timeStyle = .long

        print("    Started at: \(dateFormatter.string(from: startDate))")
        print("  Completed at: \(dateFormatter.string(from: endDate))")

        //=====================================================================
        // 10. Delete the job.
        //=====================================================================

        print("\nDeleting the job...")
        _ = await deleteJob(glueClient: glueClient, name: jobName)

        //=====================================================================
        // 11. Delete the database and tables created by this example.
        //=====================================================================

        print("Deleting the database...")
        _ = await deleteDatabase(glueClient: glueClient, name: databaseName, withTables: true)

        //=====================================================================
        // 12. Delete the crawler.
        //=====================================================================

        print("Deleting the crawler...")
        if !(await deleteCrawler(glueClient: glueClient, name: crawlerName)) {
            return
        }
    }
}

/// The program's asynchronous entry point.
@main
struct Main {
    static func main() async {
        let args = Array(CommandLine.arguments.dropFirst())

        do {
            let command = try ExampleCommand.parse(args)
            try await command.runAsync()
        } catch {
            ExampleCommand.exit(withError: error)
        }
    }    
}
// snippet-end:[swift.glue.scenario]