59 lines
2.4 KiB
C#
59 lines
2.4 KiB
C#
 
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namespace PrivaPub.Infrastructure.Backup
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{
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// What Program asks before migrations: whether a restore waits, and what this process does about it. The service carries
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// it out; a command waits for it (exit 75, EX_TEMPFAIL), except asking how it went.
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public static class MaintenanceGate
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{
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/// <summary>The exit code that stops systemd restarting the service (RestartPreventExitStatus=75): a restore gave up.</summary>
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public const int TryLater = 75;
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/// <summary>Null to go on booting; else the code to exit with.</summary>
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public static async Task<int?> Enter(IServiceProvider services, string[] command, CancellationToken token)
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{
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var backups = services.GetRequiredService<Backups>();
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var logger = services.GetRequiredService<ILoggerFactory>().CreateLogger(nameof(MaintenanceGate));
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if (command != default)
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{
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var waiting = RestoreMarker.Read(backups.Root);
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if (waiting == default || command is ["restore", ..])
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return default;
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Console.Error.WriteLine($"the restore of {waiting.Backup} is {waiting.State}{(waiting.Error == default ? string.Empty : $" ({waiting.Error})")}: try again once the service has carried it out (PrivaPub admin restore --status)");
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return TryLater;
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}
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return await ServerRestore.ApplyPending(backups.Context(), logger, token) switch
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{
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RestoreOutcome.Failed => 1,//systemd starts it again, and the next attempt redoes everything
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RestoreOutcome.GaveUp => TryLater,
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_ => (int?)null
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};
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}
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}
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// A restore asked for while the service runs (from the administrator's page or the CLI): the service stops within
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// seconds, systemd starts it again, and the restore runs before anything else.
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public class RestoreWatcher(Backups backups, IHostApplicationLifetime lifetime, ILogger<RestoreWatcher> logger) : BackgroundService
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{
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static readonly TimeSpan Interval = TimeSpan.FromSeconds(3);
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protected override async Task ExecuteAsync(CancellationToken stoppingToken)
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{
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while (!stoppingToken.IsCancellationRequested)
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{
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try
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{
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await Task.Delay(Interval, stoppingToken);
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}
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catch (OperationCanceledException)
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{
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return;
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}
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if (RestoreMarker.Read(backups.Root) is { State: "pending" } marker)
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{
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logger.LogWarning("A restore of {Backup} was asked for by {RequestedBy}: stopping, to restore it at the next start", marker.Backup, marker.RequestedBy);
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lifetime.StopApplication();
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return;
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}
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}
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}
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}
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}
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