Make proxy connect timeout configurable via application properties

[ASR4]

Description

Both ProxyService and GrpcProxyService use a hardcoded 3-second timeout. In GrpcProxyService there is an explicit TODO acknowledging this:

// TODO: Use the configuration plan to determine the timeout.
long timeout = 3000; // Default timeout of 3 seconds.

In ProxyService, the HttpClient is constructed as a static field with a hardcoded connect timeout:

private static final HttpClient httpClient = HttpClient.newBuilder()
      .connectTimeout(Duration.ofSeconds(3))
      ...

Operators currently have no way to adjust this without rebuilding the image. A slow backend (e.g. an on-premises gRPC service or a large GraphQL query) will always timeout after 3 seconds with no recourse.

Proposed change

Expose two config properties in application.properties with defaults that preserve the current behaviour:

• Connect/request timeout for HTTP backend calls (in seconds, default: 3)
  reshapr.proxy.backend.timeout.http=${RESHAPR_PROXY_BACKEND_TIMEOUT_HTTP:3}
• Deadline for gRPC backend calls (in milliseconds, default: 3000)
  reshapr.proxy.backend.timeout.grpc=${RESHAPR_PROXY_BACKEND_TIMEOUT_GRPC:3000}

Injected via @ConfigProperty in ProxyService and GrpcProxyService. No behaviour change for existing deployments.

What this is not

This is proxy-level configuration only. Per-service timeout control driven by ConfigurationPlan is a larger change involving the data model and proto definitions and is out of scope for this issue.

Details

• Module: proxy
• Files:
  - proxy/src/main/java/io/reshapr/proxy/proxy/ProxyService.java
  - proxy/src/main/java/io/reshapr/proxy/proxy/GrpcProxyService.java
  - proxy/src/main/resources/application.properties
• reShapr version: 0.0.8

[lbroudoux]

I think the way to go is to have the backend timeout configurable per configuration plan, as identified in #17. The default value - if no value is specified via configuration plan - could be configurable per application.properties though. What do you think?

[ASR4]

Good point, also I think you meant #15 rather than #17? Agreed that per-ConfigurationPlan is the right end state. Happy to take that on as a single PR that covers the full path:

1. Add a backendTimeout field to ConfigurationPlan (entity + Flyway migration)
2. Add it to the Configuration message in eds-v1.proto
3. Plumb it through ConfigurationEntry in the proxy registry
4. Use it in both ProxyService and GrpcProxyService, falling back to an application.properties default (preserving the current 3s behavior)

Would you prefer this to also close #15, or keep them as separate issues? And any preference on the property name — something like reshapr.gateway.backend.default-timeout?

[lbroudoux]

Yeah, you're right: I meant #15 (instead of 17). 👍

There's the PR #55 that I'd like to merge and that covers steps from 1-3. However, it doesn't cover the CLI and it doesn't integrate a default configurable value like we discussed (reshapr.gateway.backend.default-timeout could be the correct name BTW).

Maybe wait for #55 to be merged and then, please add the CLI part and the configurable default timeout if you wish?

[lbroudoux]

Hey @ASR4
#55 has been merged and you can work on this if you want.