public CacheableHealthChecksBuilder(IHealthChecksBuilder builder, CacheableHealthChecksServiceOptions options)
{
this.builder = builder;
this.options = options;
Services = builder.Services;
}
private HealthReportEntry BuildAndCacheReportEntry(string cacheKey, HealthCheckRegistration registration,
CacheableHealthChecksServiceOptions cacheOptionsValue,
IOptionsSnapshot <RegistrationOptions> optionsSnapshot, HealthCheckResult result, TimeSpan duration)
{
var opts = optionsSnapshot.Get(registration.Name);
var expiresIn = opts.CacheDuration ?? cacheOptionsValue.DefaultCacheDuration;
return(BuildAndCacheReportEntry(cacheKey, expiresIn, result.Status, result.Description, duration,
result.Exception, result.Data));
}
private HealthReportEntry BuildAndCacheExceptionReport(string cacheKey, HealthCheckRegistration registration,
CacheableHealthChecksServiceOptions cacheOptionsValue,
IOptionsSnapshot <RegistrationOptions> optionsSnapshot, Exception exception, TimeSpan duration)
{
var opts = optionsSnapshot.Get(registration.Name);
var expiresIn = opts.ExceptionCacheDuration ??
cacheOptionsValue.CachedExceptionsDuration ?? cacheOptionsValue.DefaultCacheDuration;
return(BuildAndCacheReportEntry(cacheKey, expiresIn, HealthStatus.Unhealthy, exception.Message, duration,
exception, new Dictionary <string, object>()));
}
/// <summary>
/// Add the <see cref="CacheableHealthCheckService"/>
/// </summary>
/// <param name="services"></param>
/// <param name="setup"></param>
/// <returns></returns>
public static IHealthChecksBuilder AddHealthChecks(this IServiceCollection services, Action <CacheableHealthChecksServiceOptions> setup)
{
var builder = services.AddHealthChecks();
services.RemoveAll <HealthCheckService>();
services.AddSingleton <HealthCheckService, CacheableHealthCheckService>();
services.Configure(setup);
var options = new CacheableHealthChecksServiceOptions();
setup(options);
return(new CacheableHealthChecksBuilder(builder, options));
}
private async Task <HealthReportEntry> RunCheckAsync(IServiceScope scope, HealthCheckRegistration registration, CacheableHealthChecksServiceOptions cacheOptionsValue, CancellationToken cancellationToken)
{
cancellationToken.ThrowIfCancellationRequested();
// If the health check does things like make Database queries using EF or backend HTTP calls,
// it may be valuable to know that logs it generates are part of a health check. So we start a scope.
using (logger.BeginScope(new HealthCheckLogScope(registration.Name)))
{
var cacheKey = $"{cacheOptionsValue.CachePrefix}{registration.Name}";
if (memoryCache.TryGetValue(cacheKey, out HealthReportEntry entry))
{
Log.HealthCheckFromCache(logger, registration, entry);
Log.HealthCheckData(logger, registration, entry);
}
else
{
var cacheable = registration.Tags.Any(a => a == cacheOptionsValue.Tag);
var optionsSnapshot = scope.ServiceProvider.GetService <IOptionsSnapshot <RegistrationOptions> >();
var healthCheck = registration.Factory(scope.ServiceProvider);
var stopwatch = ValueStopwatch.StartNew();
var context = new HealthCheckContext {
Registration = registration
};
Log.HealthCheckBegin(logger, registration);
CancellationTokenSource timeoutCancellationTokenSource = null;
try
{
HealthCheckResult result;
var checkCancellationToken = cancellationToken;
if (registration.Timeout > TimeSpan.Zero)
{
timeoutCancellationTokenSource =
CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
timeoutCancellationTokenSource.CancelAfter(registration.Timeout);
checkCancellationToken = timeoutCancellationTokenSource.Token;
}
result = await healthCheck.CheckHealthAsync(context, checkCancellationToken)
.ConfigureAwait(false);
var duration = stopwatch.GetElapsedTime();
if (cacheable)
{
entry = BuildAndCacheReportEntry(cacheKey, registration, cacheOptionsValue, optionsSnapshot, result, duration);
}
else
{
entry = new HealthReportEntry(
status: result.Status,
description: result.Description,
duration: duration,
exception: result.Exception,
data: result.Data,
tags: registration.Tags);
}
Log.HealthCheckEnd(logger, registration, entry, duration);
Log.HealthCheckData(logger, registration, entry);
}
catch (OperationCanceledException ex) when(!cancellationToken.IsCancellationRequested)
{
var duration = stopwatch.GetElapsedTime();
if (cacheable && cacheOptionsValue.CacheExceptions)
{
entry = BuildAndCacheExceptionReport(cacheKey, registration, cacheOptionsValue, optionsSnapshot, ex, duration);
}
else
{
entry = new HealthReportEntry(
status: HealthStatus.Unhealthy,
description: "A timeout occured while running check.",
duration: duration,
exception: ex,
data: null);
}
Log.HealthCheckError(logger, registration, ex, duration);
}
// Allow cancellation to propagate if it's not a timeout.
catch (Exception ex) when(ex as OperationCanceledException == null)
{
var duration = stopwatch.GetElapsedTime();
if (cacheable && cacheOptionsValue.CacheExceptions)
{
entry = BuildAndCacheExceptionReport(cacheKey, registration, cacheOptionsValue, optionsSnapshot, ex, duration);
}
else
{
entry = new HealthReportEntry(
status: HealthStatus.Unhealthy,
description: ex.Message,
duration: duration,
exception: ex,
data: null);
}
Log.HealthCheckError(logger, registration, ex, duration);
}
finally
{
timeoutCancellationTokenSource?.Dispose();
}
}
return(entry);
}
}