This repo contains blank templates for developing custom policies for use with the .NET resilience library Polly.
The ReactiveCustomPolicyTemplate folder contains example code for a custom reactive Polly policy.
Reactive policies react to configured Exceptions or returned results. For instance, they might take some remediating action based on the fault, log it, or some other action.
eg Policy.Handle<FooException>().FooReactivePolicy(...)
The ProactiveCustomPolicyTemplate folder contains example code for a custom proactive Polly policy.
Proactive policies act for all executions, whether they involve a fault or success. For instance, a policy to log execution duration (whatever the outcome) would be a proactive policy.
The code in this repo is extensively commented to show how policies fit together.
We have also published a series of four blog posts:
- Part I: Introducing custom Polly policies and the Polly.Contrib
- Part II: Authoring a non-reactive custom policy (a policy which acts on all executions)
- Part III: Authoring a reactive custom policy (a policy which react to faults)
- Part IV: Custom policies for all execution types: sync and async, generic and non-generic
The main implementations are made in the *Engine.cs files; the other classes host your derived Policy classes (so that the policies can fit into PolicyWrap) and configuration syntax.
For examples of existing policy implementations, see:
- Polly.Contrib.TimingPolicy, an example proactive policy - links to blog Part II
- Polly.Contrib.LoggingPolicy, an example reactive policy - links to blog Part III
- the main Polly repo - look in the sub-folders named by policy type (
Retryetc), for any of the*Engine.csfiles implementing policy behaviour
Fork this repo and dig in!
To test your policy as you develop, you can drive your policy from unit-tests, or from a simple console app, as Polly.Contrib.TimingPolicy demonstrates.
Just reference Polly nuget (>=v7.0) in your app and follow the principles outlined in the examples.
(You don't need the .sln and .csproj structures in this repo - they just host the examples and show how to build to a nuget package.)
The templates contain a build script that will build the custom policy into a nuget package.
If you want to publish your custom policy on nuget, we recommend bringing your contrib into the Polly.Contrib organisation - see below.
Reach out to the Polly team at our slack channel or the main Polly project Github.
We can set up a repo in the Polly.Contrib organisation - you'll have full rights to this repo, to manage and deliver your awesomeness to the Polly community!
If you already have your custom policy in a github repo, we can also just move the existing repo into the Polly.Contrib org - you still retain full rights over the repo and management of the content, but the contrib gets official recognition under the Polly.Contrib banner.
If you have a contribution to Polly that isn't a policy - for example, a cache provider, or some wait-and-retry strategies - see instead our repo Polly.Contrib.BlankTemplate.