add shared aggregator client

[Alenar]

Content

This PR add a new mithril-aggregator-client internal crate that define a api allowing to fetch and send data through Http to a Mithril Aggregator.

This is a first step that define the internal mechanism but all available queries are yet to be implemented in order to replace existing clients in the aggregator, signer and client lib.

Details

• new mithril-aggregator-client internal crate
  • Define a AggregatorClient struct that expose one method: send
  • This send method can take any object that implement the, crate internal, AggregatorQuery trait
  • The AggregatorClient is meant to be built using a builder pattern accessible from either AggregatorClient::builder or directly though the builder: AggregatorClientBuilder::new(aggregator_url)
  • The client have all features that are available on our three builders:
    • timeout
    • relay endpoint proxy
    • aggregator url sanitation
    • mithril api version header
    • api version mismatch warning
    • configurable additional header
    • error analysis
    • mithril specific 450 http code error handling (registration round not opened)
  • One query is defined as example, including tests: CertificateDetailsQuery to retrieve a certificate with a given hash or the latest genesis
• mithril-common - make ApiVersionProviderTestExtensions that defines three test utilities: update_open_api_versions (test method moved from ApiVersionProvider public api), new_with_default_version({Version}), and new_failing

Pre-submit checklist

• Branch
  • Tests are provided (if possible)
  • Crates versions are updated (if relevant)
  • Commit sequence broadly makes sense
  • Key commits have useful messages
• PR
  • All check jobs of the CI have succeeded
  • Self-reviewed the diff
  • Useful pull request description
  • Reviewer requested
• Documentation
  • Update README file (if relevant)
  • No new TODOs introduced

Comments

Todo

A TODO is added because of an unwrap in AggregatorClient.send:

// Todo: error handling ? Reuse the version in `warn_if_api_version_mismatch` ?
let current_api_version = self.api_version_provider.compute_current_version().unwrap();

This unwrap is a strict copy from all three existing aggregator client behavior, this raise a question if a mithril api version, and by extension sending the mithril-api-version header, is mandatory or not. Especially since the behavior of warn_if_api_version_mismatch, that is used afterward when handling the response, in all three clients is to not crash if an error is raised when computing the version.

Api design choice

The choice have been made of making the AggregatorQuery trait internal to the crate, this means childs crates can't define custom queries.
The idea behind this choice is that the public api of the crate avoid exposing types from third party, non-mithril, crates, but the AggregatorQuery mechanism need to pass around a reqwest::Response, so making this trait public would be exposing a "leaking" abstraction.

We may decide instead to take that upfront if we think that defining queries on a child crate is useful, but since all messages that are available from a mithril aggregator are defined in the shared mithril-common crate right now there's no difficulty to define all queries in the mithril-aggregator-client crate.

Issue(s)

Relates to #2640

[Copilot]

Pull Request Overview

This PR introduces a new shared aggregator client for the Mithril network, providing a reusable HTTP client library for communicating with Mithril aggregators. The client includes query abstractions, error handling, API version compatibility checking, and comprehensive test coverage.

Key changes:

• New mithril-aggregator-client crate with HTTP client functionality
• API version provider extensions for testing
• Certificate details query implementation
• Comprehensive error handling and logging

Reviewed Changes

Copilot reviewed 18 out of 19 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
internal/mithril-aggregator-client/	Complete new crate implementing the aggregator client with builder pattern, query system, and error handling
mithril-common/src/api_version.rs	Added Default implementation and test extensions for APIVersionProvider
mithril-common/src/test/api_version_extensions.rs	New test utilities for API version provider testing
README.md	Updated documentation to include the new aggregator client
Cargo.toml	Added new crate to workspace members
.github/workflows/ci.yml	Updated CI to include documentation generation for the new crate

[github-actions]

Test Results

    4 files  ±  0    158 suites  +4   22m 33s ⏱️ -11s
2 152 tests + 31  2 152 ✅ + 31  0 💤 ±0  0 ❌ ±0 
6 602 runs  +124  6 602 ✅ +124  0 💤 ±0  0 ❌ ±0 

Results for commit 70c6c51. ± Comparison against base commit cdc4548.

♻️ This comment has been updated with latest results.

[dlachaume]

Just need to add WASM compatibility, otherwise LGTM 🚀.

[turmelclem]

LGTM 🦙