To build a custom `push` logic using `gix` (the `gitoxide` library), you need to navigate both high-level "porcelain" APIs and lower-level "plumbing" crates.

[community-stevedores-org]

Summary 💡

To build a custom push logic using gix (the gitoxide library), you need to navigate both high-level "porcelain" APIs and lower-level "plumbing" crates. While gix is increasingly feature-complete, a manual push implementation requires coordinating several distinct systems: reference resolution, object pack generation, and network transport.

1. Architecture Overview

The architecture follows a layered approach, moving from high-level repository management down to the raw byte-stream protocol.

• Repository Layer (gix::Repository): The entry point. It manages the local object database (ODB) and reference store.
• Remote & Connection Layer (gix::Remote): Handles remote configurations (URLs, refspecs) and establishes the initial connection.
• Protocol Layer (gix-protocol): Manages the "Git Protocol" (usually V2). It handles the handshake and the negotiation of which objects the server already has.
• Object/Pack Layer (gix-pack, gix-odb): Responsible for finding all commits, trees, and blobs that exist locally but not on the remote, then bundling them into a "Thin Pack."
• Transport & Auth Layer (gix-transport, gix-credentials): The "pipes." It manages the literal SSH or HTTPS connection and integrates with credential helpers to provide tokens or keys.

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2. Required Dependencies

Add the following to your Cargo.toml. To minimize build times, it is best to enable only the features you need.

[dependencies]
# The main entry point
gix = { version = "0.67", features = ["blocking-http-transport-curl", "credentials", "revision"] }

# Plumbing crates (sometimes re-exported by gix, but often needed directly for custom logic)
gix-protocol = "0.46"
gix-transport = "0.43"
gix-pack = "0.54"

# For error handling and async if needed
anyhow = "1.0"

Note: Use blocking-http-transport-reqwest instead of curl if you prefer a pure-Rust HTTP stack.

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3. Implementation Plan

Implementing push logic involves five critical steps:

Step 1: Initialize and Resolve

Open your local repository and identify the remote (usually origin). You must resolve your local HEAD or a specific branch to a precise Object ID (OID).

• Action: Use gix::open() and repo.find_remote().

Step 2: Connection & Handshake

Establish a connection to the remote URL. This triggers a "handshake" where the server tells you its capabilities and its current list of references.

• Action: Call remote.connect(gix::remote::Direction::Push).

Step 3: Negotiation (What to send?)

Compare your local references with the remote's references. You need to determine the "set difference": which commits do you have that they don't?

• Action: Use gix-protocol to list remote refs and gix-revwalk to find the local commits that need to be sent.

Step 4: Pack Creation (The "Thin Pack")

Git doesn't send files individually; it sends a compressed .pack file. For a push, you create a "Thin Pack" containing only the new objects. The server will "re-index" this pack upon receipt.

• Action: Use gix_pack::data::output to stream objects into a pack format.

Step 5: The Transfer & Ref Update

Send the pack file over the transport. Once the transfer is complete, you send a final command to the server to update its branch pointer (e.g., move refs/heads/main from OID A to OID B).

• Action: Execute the Push command via the established Connection.

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4. High-Level API Sketch

Here is how the logic looks when using the library's higher-level abstractions:

use gix::prelude::*;

fn main() -> anyhow::Result<()> {
    let repo = gix::open(".")?;
    let mut remote = repo.find_remote("origin")?;

    // 1. Connect with Push intent
    let mut connection = remote.connect(gix::remote::Direction::Push)?;

    // 2. Prepare the push (Map local branch to remote refspec)
    // This handles the negotiation of what needs to be sent
    let push_plan = connection.prepare_push(vec!["refs/heads/main:refs/heads/main"])?;

    // 3. Execute (Pack, Transfer, and Update)
    let outcome = push_plan.receive_pack(&mut gix::progress::Discard)?;

    println!("Push successful! Updated refs: {:?}", outcome.updates);
    Ok(())
}

Next Steps

Would you like me to provide a lower-level plumbing example that shows exactly how the packfile is generated from the object database, or would you prefer a deep dive into handling SSH/HTTPS authentication specifically for GitHub?

Motivation 🔦

gix push