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How to define Polly policies when working with Refit library in ASP.NET Core?
Note: this is based on my question on SO and subsequent activity there
I am trying to add resilience using Polly to HTTP calls that are performed using Refit library.
I am using the Refit factory method RestService.For<> and I have a working code, but I feel it is way more complex than it should be:
The refit interface
[Headers("Authorization: Bearer")]
public interface IBarIntegration
{
[Get("/api/ext/Foo/GetFooBriefInfo")]
Task<ApiResponse<GetFooBriefInfoForFooDto>> GetFooBriefInfo(GetFooBriefInfoForFooInputDto inputData);
}
Factory class that also configures the authentication
internal sealed class BarApiClientHelper : IBarApiClientHelper
{
private readonly IOptionsSnapshot<BarApiSettings> _BarSettings;
private readonly IAccessTokenHelperService _accessTokenHelperService;
public BarApiClientHelper(IOptionsSnapshot<BarApiSettings> BarSettings, IAccessTokenHelperService accessTokenHelperService)
{
_BarSettings = BarSettings;
_accessTokenHelperService = accessTokenHelperService;
}
public async Task<TApiClient> CreateApiClient<TApiClient>(CancellationToken token)
{
string baseUrl = _BarSettings.Value.BaseUrl;
string accessToken = await _accessTokenHelperService.GetAccessToken(token);
var refitClient = RestService.For<TApiClient>(baseUrl, new RefitSettings
{
AuthorizationHeaderValueGetter = () => Task.FromResult(accessToken)
});
return refitClient;
}
}
Example call
public async Task<GetFooBriefInfoForFooDto> GetFooBriefInfo(string upn, CancellationToken token)
{
var apiClient = await _clientHelper.CreateApiClient<IBarIntegration>(token);
var retrialPolicy = _registry.Get<AsyncRetryPolicy<IApiResponse>>(DefaultRetrialPolicy);
var func = async () => (IApiResponse) await apiClient.GetFooBriefInfo(new GetFooBriefInfoForFooInputDto { FooContactUpn = upn });
var FooInfo = (ApiResponse<GetFooBriefInfoForFooDto>) await retrialPolicy.ExecuteAsync(func);
await FooInfo.EnsureSuccessStatusCodeAsync();
return FooInfo.Content!;
}
1 answer
Refit allows such configuration out of the box bt using AddRefitClient (which resembles the well-known AddHttpClient). This indeed requires explicit configuration for the HttpClient, but the configuration and usage will be simpler:
Refit and resilience configuration
private static IServiceCollection ConfigureResilience(this IServiceCollection services)
{
services
.AddRefitClient(typeof(IBarIntegration), (sp) =>
{
var accessTokenHelperService = sp.GetRequiredService<IAccessTokenHelperService>();
return new RefitSettings
{
AuthorizationHeaderValueGetter = () => accessTokenHelperService.GetAccessToken(default)
};
})
.ConfigureHttpClient((sp, client) =>
{
var BarSettings = sp.GetRequiredService<IOptions<BarApiSettings>>();
string baseUrl = BarSettings.Value.BaseUrl;
client.BaseAddress = new Uri(baseUrl);
})
.AddTransientHttpErrorPolicy(policyBuilder => policyBuilder.WaitAndRetryAsync( Backoff.DecorrelatedJitterBackoffV2(TimeSpan.FromSeconds(1), RetryPolicyMaxCount)
)
);
.WaitAndRetryAsync(Backoff.DecorrelatedJitterBackoffV2(TimeSpan.FromSeconds(1), RetryPolicyMaxCount)));
return services;
}
Refit interface
[Headers("Authorization: Bearer")]
public interface IBarIntegration
{
[Get("/api/ext/Foo/GetFooBriefInfo")]
Task<GetFooBriefInfoForFooDto> GetFooBriefInfo(GetFooBriefInfoForFooInputDto inputData);
}
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