Replacing reqwest crate with async_minreq crate

[psg-19]

Addresses #121

Overview

This PR replaces our reqwest-based async client with a lightweight async-minreq fork. All existing unit tests pass, but because async-minreq pulls in Tokio 1.44.0 and Tokio-rustls 0.26.2, the project’s MSRV must be bumped to 1.71.0 in CI.

Changes

• Dependency swap

  • Removed reqwest (and its feature flags)
  • Added
    async_minreq = { git = "https://github.com/psg-19/async-minreq" }

• Async client rewrite

  • Updated async.rs to use the async-minreq API for GET/POST, timeouts, retries, and HTTPS.

• Tests & MSRV

  • Verified unit tests pass on Rust 1.71.0.
  • CI workflows now declare rust-version = "1.71.0" to match Tokio’s MSRV.

Looking forward to feedback on these changes and any suggestions for improvement!

Binary Size And Dependency tree

Feature	Command Used	Async Minreq		Reqwest
		Binary Size	Dependency Tree	Binary Size	Dependency Tree
build (debug)	cargo build	6409 KB	298	6514 KB	434
build (release)	cargo build -r	1627 KB	298	1616 KB	434
async	cargo build --no-default-features --features async	1709 KB	290	1914 KB	396
async-https	cargo build --no-default-features --features async-https	2034 KB	295	1915 KB	431
async-https-native	cargo build --no-default-features --features async-https-native	1710 KB	314	1915 KB	431
async-https-rustls	cargo build --no-default-features --features async-https-rustls	2034 KB	295	1876 KB	423
async-https-rustls-manual-roots	cargo build --no-default-features --features async-https-rustls-manual-roots	NA	NA	1876 KB	420

Command used for calculating dependency tree -> cargo tree --no-default-features --features xyz | wc -l

My Machine specs -> intel i7 12th gen, rtx 3050ti

OS -> windows subsystem for linux

Checklists

All Submissions:

• I’ve signed all my commits
• I followed the contribution guidelines
• I ran cargo fmt and cargo clippy before committing

New Features:

• I’ve added tests for the new feature
• I’ve added docs for the new feature

[tnull]

This is a pretty substantial change that also breaks compatibility between rust-esplora-client versions. That said, I really like the idea of eventually getting rid of the huge dependency tree of reqwest.

Given that this PR seems to be based on a draft fork-of-a-fork branch that was edited without any code review, I think it would be very important to move the async-minreq crate to the bitcoindevkit org, have it undergo proper code review, and introduce co-maintainers before we'd want to take on this new dependency.

[notmandatory]

Good start and glad to see tests are passing. Per our call here are comments so far.

[notmandatory]

@tnull thanks for taking a look, @psg-19 is my summer of bitcoin mentee. I agree this is a big change but as you pointed out the goal is to reduce the dependency tree. I and @psg-19 will work with @BEULAHEVANJALIN on async_minreq to upstream changes we need and do any other work to get that crate ready for production use.

[coveralls]

Pull Request Test Coverage Report for Build 16971959331

Details

• 21 of 26 (80.77%) changed or added relevant lines in 1 file are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage remained the same at 86.919%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/async.rs	21	26	80.77%

Files with Coverage Reduction	New Missed Lines	%
src/async.rs	1	80.0%

Totals
Change from base Build 16626978737:	0.0%
Covered Lines:	1010
Relevant Lines:	1162

---

💛 - Coveralls

[notmandatory]

Another option we should consider for this PR is making async_minreq an optional "experimental" features so projects can help test it out while the async_minreq crate matures. The down-side is this doesn't follow cargo convention about not having conflicting features, will blow-up the number of feature flags and make the code a bit harder to read/reason about. But still worth a look, could rename features like this:

async-minreq = ["async_minreq", "async_minreq/proxy", "tokio?/time"]
async-minreq-https = ["async-minreq", "async_minreq/https"]
async-minreq-https-native = ["async-minreq", "async_minreq/https-native"]
async-minreq-https-rustls = ["async-minreq", "async_minreq/https-rustls"]
async-minreq-https-rustls-manual-roots = ["async-minreq"]

[notmandatory]

The latest commit to feature flag the async-minreq code looks good! I have a few suggestions for finishing this off:

1. put the current async code blocks before the async-minreq blocks so that if somehow both features are enabled the current reqwest based code will return first, also the diff will be easier to review against the current code.
2. I think I saw a couple places where the final return statements for the async feature aren't feature gated.
3. The README should be updated to state the new MSRV is updated to 1.71 and what the new pinned dependencies are, or similar to how it's done in the bdk repo you can put all the pinning in a pin-msrv.sh script and just reference that in both the README and use it in the CI workflows.
4. Also in the README you should describe the available feature flags and say that the async-minreq one is currently "experimental" but may become the only async client In the future once it's more mature.
5. Cleanup commit history and follow conventional commits style commit messages (I can show you how to do this with 'git rebase').

[notmandatory]

I found two small doc changes that are needed, but otherwise this looks good and I should be able to approve once those are fixed and I've done a little manual testing.