Joseph Doherty
32 lines
1.5 KiB
C#
32 lines
1.5 KiB
C#
using Akka.Actor;
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using Microsoft.Extensions.Diagnostics.HealthChecks;
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namespace ZB.MOM.WW.ScadaBridge.Host.Health;
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/// <summary>
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/// /health/active check: Healthy only on the oldest Up member — the node that
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/// hosts the cluster singletons. Replaces the shared package's leader-based
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/// ActiveNodeHealthCheck (review 01 [High]): leadership is address-ordered and
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/// diverges from singleton placement after a restart, and during a partition
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/// BOTH nodes compute themselves leader, so Traefik served both. Oldest-member
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/// semantics keep exactly one active node through a partition (the non-oldest
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/// side still sees the old oldest member until SBR resolves membership).
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/// </summary>
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public sealed class OldestNodeActiveHealthCheck : IHealthCheck
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{
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private readonly ActorSystem _system;
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/// <summary>Initializes a new <see cref="OldestNodeActiveHealthCheck"/> bound to the running actor system.</summary>
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/// <param name="system">The live cluster actor system.</param>
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public OldestNodeActiveHealthCheck(ActorSystem system) => _system = system;
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/// <inheritdoc />
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public Task<HealthCheckResult> CheckHealthAsync(HealthCheckContext context, CancellationToken ct = default)
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{
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var cluster = Akka.Cluster.Cluster.Get(_system);
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return Task.FromResult(ClusterActivityEvaluator.SelfIsOldest(cluster)
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? HealthCheckResult.Healthy("oldest Up member (singleton host)")
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: HealthCheckResult.Unhealthy("not the oldest Up member (standby)"));
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}
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}
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