public async Task Invoke(HttpContext context)
{
PathString subpath;
if (!context.Request.Path.StartsWithSegments(_options.Path, out subpath))
{
await _next(context);
return;
}
var policyName = subpath.ToUriComponent().Trim('/');
if (policyName.Length == 0)
{
policyName = Constants.DefaultPolicy;
}
if (_options.AuthorizationPolicy != null)
{
var principal = await SecurityHelper.GetUserPrincipal(context, _options.AuthorizationPolicy);
if (!await _authorizationService.AuthorizeAsync(principal, context, _options.AuthorizationPolicy))
{
_logger.AuthorizationFailed();
await _next(context);
return;
}
}
HealthCheckPolicy policy = _policyProvider.GetPolicy(policyName);
if (policy == null)
{
_logger.InvalidPolicy(policyName);
await _next(context);
return;
}
var response = context.Response;
var healthCheckResponse = await _healthService.CheckHealthAsync(policy);
if (healthCheckResponse.HasErrors)
{
_logger.HealthCheckFailed(healthCheckResponse.Errors);
if (healthCheckResponse.HasCriticalErrors)
{
response.StatusCode = StatusCodes.Status503ServiceUnavailable;
response.WriteRetryAfterHeader(healthCheckResponse.RetryAfter);
}
}
else
{
_logger.HealthCheckSucceeded();
response.StatusCode = StatusCodes.Status200OK;
}
if (_options.SendResults && !HttpMethods.IsHead(context.Request.Method))
{
response.ContentType = ApplicationJson;
using (var writer = new HttpResponseStreamWriter(response.Body, Encoding.UTF8, 1024, _bytePool, _charPool))
{
using (var jsonWriter = new JsonTextWriter(writer))
{
jsonWriter.ArrayPool = _jsonCharPool;
jsonWriter.CloseOutput = false;
_jsonSerializer.Serialize(jsonWriter, healthCheckResponse.Results);
}
}
}
}
public CanaryMiddleware(
RequestDelegate next,
IOptions <CanaryOptions> options,
ILoggerFactory loggerFactory,
IHealthCheckService healthService,
IHealthCheckPolicyProvider policyProvider,
IServerSwitch serverSwitch,
IAuthorizationService authorizationService)
{
if (next == null)
{
throw new ArgumentNullException(nameof(next));
}
if (options == null)
{
throw new ArgumentNullException(nameof(options));
}
if (loggerFactory == null)
{
throw new ArgumentNullException(nameof(loggerFactory));
}
if (healthService == null)
{
throw new ArgumentNullException(nameof(healthService));
}
if (policyProvider == null)
{
throw new ArgumentNullException(nameof(policyProvider));
}
if (authorizationService == null)
{
throw new ArgumentNullException(nameof(authorizationService));
}
if (authorizationService == null)
{
throw new ArgumentNullException(nameof(authorizationService));
}
_next = next;
_options = options.Value;
_logger = loggerFactory.CreateLogger <CanaryMiddleware>();
_healthService = healthService;
_serverSwitch = serverSwitch;
_authorizationService = authorizationService;
if (_options.EnableHealthCheck)
{
var defaultPolicy = policyProvider.GetPolicy(_options.PolicyName);
if (defaultPolicy == null)
{
throw new ArgumentException($"{nameof(_options.PolicyName)} '{_options.PolicyName}' is not a valid policy.", nameof(_options));
}
_defaultPolicy = defaultPolicy;
}
}