ComposeLens

ComposeLens is an open-source Rust library for parsing, inspecting, processing, editing, and rendering Docker Compose files. It keeps authored YAML separate from processed project meaning, so callers choose when interpolation, merging, profile selection, path handling, or compatibility validation happens.

Guides · Rust API · crates.io · Source code

Why use it

Preserve source locations, unknown fields, extensions, and meaningful short or long syntax.
Inspect one authored document or a provenance-rich multi-file project view.
Supply environment values, include content, path policy, profiles, and target versions explicitly.
Return structured diagnostics and partial results instead of printing or terminating the process.
Produce deterministic Compose YAML or make focused edits without rewriting unrelated source.

ComposeLens never starts containers, contacts a runtime, reads the process environment implicitly, or converts Compose directly into another format. Cross-format conversion belongs to BoxFerry.

Start

Add the crate:

cargo add compose-lens

Parse an in-memory document:

use compose_lens::{model::ComposeDocument, source::SourceId, syntax::SyntaxDocument};

let source = "---\nservices:\n  web:\n    image: example.invalid/web:1\n";
let syntax = SyntaxDocument::parse(SourceId::new(1), source).expect("source fits");
let parsed = ComposeDocument::parse(syntax.document());

assert!(parsed.document().and_then(|document| document.service("web")).is_some());
assert!(parsed.diagnostics().is_empty());

Rust 1.85.0 or newer is required.

Processing model

source text -> syntax -> typed document -> loaded inputs
            -> optional interpolation -> merge -> optional profiles
            -> project view or validation -> rendering

Each arrow is an explicit API boundary. A caller may stop at the narrowest stage that answers its question, and every stage keeps diagnostics and source evidence available.

Documentation

Repository-specific instructions for coding agents are in AGENTS.md.

Open source