Discovery public API review and refactorings

[bart-vmware]

Description

This PR is the result of the public API review for Steeltoe Service Discovery, along with various bug fixes, improvements, and refactorings. Changes are listed below.

General

• Remove unused/redundant interfaces and base classes: they seemed great for extensibility, however their structures matched with one very specific implementation
• Use IOptions pattern and respond to configuration changes
• Applied Public API guidance from Public API Surface Area Review #897 (comment)
• More async all-the-way, reduced sync-over-async usage
• Types and members are annotated for nullable reference types
• Improved test coverage, testing more execution flows instead of single classes
• Improved logging output, which enables to track what's going on with relevant contextual information
• Lots of corrections in triple-slash documentation comments, more types are documented now
• Remove redundant [InternalsVisibleTo] entries, optimize project dependencies
• Use dependency injection in most places, remove public static instances
• Drop usage of IServiceInfo and related assembly scanning attributes
• Remove redundant HostBuilder extensions, in favor of extensions on IServiceCollection
• Throw NotSupportedException instead of NotImplementedException for things that were deliberately not implemented
• Throw FormatException instead of InvalidOperationException when the conversion of primitive type fails
• Bootstrap support for using multiple active discovery clients (see below)

Load balancing

• Improve reliability of round-robin load balancer when used without distributed cache, by atomically switching to the next available service (fixes race condition)
• NoOpDiscoveryClient (and related warnings) has been removed, as load balancers can query multiple discovery clients now
• Moved consumption of service discovery (HttpClient support and load balancers) to Steeltoe.Discovery.HttpClients project
• Simpler API surface: use IHttpClientBuilder.AddServiceDiscovery<TLoadBalancer>() for a named client, or use DiscoveryHttpClientHandler for non-factory scenarios

Service Discovery

• Remove project Steeltoe.Discovery.Abstractions, move configuration-based discovery into new project Steeltoe.Discovery.Configuration
• Merge IServiceInstanceProvider into IDiscoveryClient, moved to Steeltoe.Common.Abstractions
• Remove AddServiceDiscovery and AddDiscoveryClient (registration) extension methods (which used assembly scanning), in favor of client-specific extension methods with explicit dependencies
• Multiple discovery clients can be active at the same time (one per type), Eureka/Consul can be turned off via configuration
• Remove IDiscoveryClientExtension, in favor of using the built-in D/I container
• Support for global service discovery (for all HttpClients within the app), ie: services.ConfigureHttpClientDefaults(builder => builder.AddServiceDiscovery());

Consul

• Use PeriodicTimer for background heartbeats (async and cancellable, no overlaps)
• Implement IValidateOptions, so an OptionsValidationException is thrown on an invalid configuration
• Remove setting consul:discovery:cacheTtl, which used to set global DistributedCacheEntryOptions for the entire app (dangerous and non-intuitive), you can still register this yourself, which will be picked up
• Rename undocumented setting consul:discovery:UseNetUtils to consul:discovery:UseNetworkInterfaces
• Improved detection of ASP.NET binding to hosts/IPs and ports, including the new HTTP_PORTS/HTTPS_PORTS environment variables from .NET 8
• Simplify namespaces, ie Steeltoe.Discovery.Consul.Discovery to Steeltoe.Discovery.Consul

Eureka

• Replace reflection-based fetching of management endpoint configuration (health, info) with light-up dependency
• Rename ScopedEurekaHealthCheckHandler to EurekaHealthCheckHandler
• Fix various race conditions and potentially sending a partially-updated (inconsistent) instance to Eureka
• More efficient registration/renewal, only sending non-null properties
• Optimized execution flow for periodic renewals and heartbeats, not sending more frequently than needed
• Internally use a UTC-based DateTime for timestamps, instead of long (which could be .NET ticks or Java ticks).
• Implement IValidateOptions, so an OptionsValidationException is thrown on an invalid configuration
• Prefer secure port when both secure/non-secure are returned from Eureka
• Support ASP.NET dynamic port assignment (as long as it doesn't change the local Instance ID)
• Internally use TimeSpan for timeouts and intervals, instead of seconds/milliseconds
• Fixes in determining HomePage/Status/HealthCheck URLs, support runtime-replacement of ${eureka.hostname}
• Communicate with Eureka using named HttpClient from HttpClientFactory, so the handler pipeline can be tweaked as desired (ie custom headers)
• Fixed: eureka:client:EurekaServer:RetryCount indicates the number of retries, instead of attempts
• Fixed: unhandled exception when trying to mask URL during log when the URL is invalid
• Perf: reuse JsonSerializerOptions instead of recreating it on every request
• Remove setting eureka:client:shouldOnDemandUpdateStatusChange, updates are always sent immediately when instance changes (from configuration or user code)
• Remove setting eureka:instance:defaultAddressResolutionOrder because it was never used nor documented
• Remove setting eureka:client:cacheTtl, which used to set global DistributedCacheEntryOptions for the entire app (dangerous and non-intuitive), you can still register this yourself, which will be picked up
• Rename undocumented setting eureka:instance:UseNetUtils to eureka:instance:UseNetworkInterfaces
• Support comma-separated list of multiple names in setting eureka:instance:vipAddress and eureka:instance:secureVipAddress
• Rename [Secure]VirtualHostName to [Secure]VipAddress, using multiple terms for the same thing is confusing
• Fixed: Take OverriddenStatus into account when evaluating instance status
• Config Server discovery-first now supports multiple discovery clients with light-up dependencies
• Improved detection of ASP.NET binding to hosts/IPs and ports, including the new HTTP_PORTS/HTTPS_PORTS environment variables from .NET 8
• Don't infer hostname from the URLS environment variable (ASP.NET ignores it, so will Steeltoe)
• Both secure and non-secure ports are initially disabled in configuration. Steeltoe probes for URLS/HTTP_PORTS/HTTPS_PORTS and activates them, based on what the app binds to. In Cloud Foundry, this information is inferred from the cloud environment.

Fixes #901, fixes #1107, fixes #829, fixes #786, fixes #493, fixes #480, fixes #479, fixes #121, fixes #11.

Quality checklist

• Your code complies with our Coding Style.
• You've updated unit and/or integration tests for your change, where applicable.
• You've updated documentation for your change, where applicable.
  If your change affects other repositories, such as Documentation, Samples and/or MainSite, add linked PRs here.
• There's an open issue for the PR that you are making. If you'd like to propose a new feature or change, please open an issue to discuss the change or find an existing issue.
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[bart-vmware]

/azp run Steeltoe.All

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[TimHess]

Generally looks like a huge improvement, quite a bit easier to read and understand

[bart-vmware]

/azp run Steeltoe.All

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[TimHess]

LGTM

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[sonarcloud]

Quality Gate passed

Issues
23 New issues
0 Accepted issues

Measures
1 Security Hotspot
0.0% Coverage on New Code
0.3% Duplication on New Code

See analysis details on SonarCloud

[osmedd]

Thank you! This is a huge win I think.