Add env to set environment variables for hooks (#1279)

[danielparks]

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This requires prek-test-repos/script-hooks to be updated (prek-test-repos/script-hooks#1) before tests will pass. Unfortunately, merging that PR will break tests on this repo until this PR is merged.

I only added a couple of tests here; would you like me to go through and add tests for other languages?

Closes #1279

[codecov]

Codecov Report

❌ Patch coverage is 96.82540% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.94%. Comparing base (1856285) to head (4e82569).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
crates/prek/src/run.rs	90.47%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1285      +/-   ##
==========================================
- Coverage   90.01%   89.94%   -0.07%     
==========================================
  Files          80       80              
  Lines       15754    15808      +54     
==========================================
+ Hits        14181    14219      +38     
- Misses       1573     1589      +16     

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[github-actions]

📦 Cargo Bloat Comparison

Binary size change: +0.00% (16.7 MiB → 16.7 MiB)

Expand for cargo-bloat output

Head Branch Results

 File  .text     Size          Crate Name
 0.7%   1.4% 114.7KiB           prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.6%   1.3% 107.3KiB          prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.3%   0.7%  54.7KiB           prek prek::archive::unpack::{{closure}}
 0.3%   0.7%  52.8KiB             h2 h2::proto::connection::Connection<T,P,B>::poll
 0.2%   0.5%  39.8KiB           prek prek::languages::<impl prek::config::Language>::install::{{closure}}
 0.2%   0.5%  39.2KiB          prek? <prek::cli::RunArgs as clap_builder::derive::Args>::augment_args
 0.2%   0.5%  39.2KiB           prek prek::run::{{closure}}
 0.2%   0.5%  37.3KiB          hyper hyper::proto::h1::dispatch::Dispatcher<D,Bs,I,T>::poll_loop
 0.2%   0.5%  36.9KiB regex_automata regex_automata::meta::strategy::new
 0.2%   0.5%  36.5KiB           prek prek::workspace::Workspace::discover
 0.2%   0.4%  30.8KiB           std? <core::marker::PhantomData<T> as serde_core::de::DeserializeSeed>::deserialize
 0.2%   0.4%  30.7KiB           prek prek::cli::run::run::run::{{closure}}
 0.2%   0.4%  29.8KiB           prek prek::languages::rust::installer::RustInstaller::install::{{closure}}
 0.2%   0.4%  28.4KiB           prek prek::languages::node::installer::NodeInstaller::install::{{closure}}
 0.2%   0.4%  27.9KiB             h2 h2::proto::connection::DynConnection<B>::recv_frame
 0.2%   0.3%  27.6KiB           prek prek::identify::by_extension::{{closure}}
 0.2%   0.3%  27.3KiB           prek prek::cli::run::run::run_hooks::{{closure}}
 0.2%   0.3%  26.2KiB           prek prek::cli::auto_update::update_repo::{{closure}}
 0.1%   0.3%  25.3KiB           prek prek::main
 0.1%   0.3%  24.7KiB           prek prek::hook::HookBuilder::build::{{closure}}
41.2%  88.5%   6.9MiB                And 10638 smaller methods. Use -n N to show more.
46.5% 100.0%   7.8MiB                .text section size, the file size is 16.7MiB

Base Branch Results

 File  .text     Size          Crate Name
 0.6%   1.4% 107.3KiB          prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.6%   1.4% 107.2KiB           prek prek::languages::<impl prek::config::Language>::run::{{closure}}::{{closure}}
 0.3%   0.7%  54.7KiB           prek prek::archive::unpack::{{closure}}
 0.3%   0.7%  52.8KiB             h2 h2::proto::connection::Connection<T,P,B>::poll
 0.2%   0.5%  39.8KiB           prek prek::languages::<impl prek::config::Language>::install::{{closure}}
 0.2%   0.5%  39.2KiB          prek? <prek::cli::RunArgs as clap_builder::derive::Args>::augment_args
 0.2%   0.5%  39.2KiB           prek prek::run::{{closure}}
 0.2%   0.5%  37.3KiB          hyper hyper::proto::h1::dispatch::Dispatcher<D,Bs,I,T>::poll_loop
 0.2%   0.5%  36.9KiB regex_automata regex_automata::meta::strategy::new
 0.2%   0.5%  36.5KiB           prek prek::workspace::Workspace::discover
 0.2%   0.4%  30.8KiB           std? <core::marker::PhantomData<T> as serde_core::de::DeserializeSeed>::deserialize
 0.2%   0.4%  30.7KiB           prek prek::cli::run::run::run::{{closure}}
 0.2%   0.4%  29.8KiB           prek prek::languages::rust::installer::RustInstaller::install::{{closure}}
 0.2%   0.4%  28.4KiB           prek prek::languages::node::installer::NodeInstaller::install::{{closure}}
 0.2%   0.4%  27.9KiB             h2 h2::proto::connection::DynConnection<B>::recv_frame
 0.2%   0.3%  27.6KiB           prek prek::identify::by_extension::{{closure}}
 0.2%   0.3%  27.3KiB           prek prek::cli::run::run::run_hooks::{{closure}}
 0.2%   0.3%  26.2KiB           prek prek::cli::auto_update::update_repo::{{closure}}
 0.1%   0.3%  25.3KiB           prek prek::main
 0.1%   0.3%  24.4KiB     hyper_util hyper_util::client::legacy::client::Client<C,B>::send_request::{{closure}}
41.2%  88.6%   6.9MiB                And 10633 smaller methods. Use -n N to show more.
46.5% 100.0%   7.8MiB                .text section size, the file size is 16.7MiB

[danielparks]

I added a commit to point the script test at my fork of prek-test-repos/script-hooks; it will need to be removed before merging.

[Copilot]

Pull request overview

This PR adds support for setting environment variables for hooks via a new env configuration option. This feature allows users to pass custom environment variables to hooks, which will override existing environment variables like $PATH.

Key changes:

• Added env field to hook configuration schema accepting key-value pairs of environment variable names and values
• Implemented environment variable support across all language implementations (system, script, python, ruby, rust, node, golang, lua, pygrep, docker, docker_image)
• Updated command-line argument length calculation on Unix to account for environment variable space in ARG_MAX limit
• Added documentation and tests demonstrating the new env feature

Reviewed changes

Copilot reviewed 20 out of 20 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
prek.schema.json	Added env field schema definition to both hook and manifest schemas, accepting object or null with string values
docs/configuration.md	Added comprehensive documentation for the env hook-level option with usage example showing RUSTDOCFLAGS
crates/prek/src/config.rs	Added env: Option<FxHashMap<String, String>> field to HookOptions with custom merge logic that extends rather than replaces
crates/prek/src/hook.rs	Added env: FxHashMap<String, String> field to Hook struct and initialized it in the builder
crates/prek/src/run.rs	Updated Unix ARG_MAX calculation to account for environment variable sizes, avoiding double-counting overridden variables
crates/prek/src/languages/system.rs	Added .envs(&hook.env) call to pass environment variables to system commands
crates/prek/src/languages/script.rs	Added .envs(&hook.env) call to pass environment variables to script commands
crates/prek/src/languages/python/python.rs	Added .envs(&hook.env) call after setting Python-specific environment variables
crates/prek/src/languages/ruby/ruby.rs	Added .envs(&hook.env) call after setting Ruby-specific environment variables
crates/prek/src/languages/rust/rust.rs	Added .envs(&hook.env) call after setting Rust-specific environment variables
crates/prek/src/languages/node/node.rs	Added .envs(&hook.env) call after setting Node-specific environment variables
crates/prek/src/languages/golang/golang.rs	Added .envs(&hook.env) call after setting Go-specific environment variables
crates/prek/src/languages/lua.rs	Added .envs(&hook.env) call after setting Lua-specific environment variables
crates/prek/src/languages/pygrep/pygrep.rs	Added .envs(&hook.env) call to pass environment variables to pygrep commands
crates/prek/src/languages/docker.rs	Implemented environment variable passing via -e flags on docker run command line
crates/prek/src/languages/docker_image.rs	Implemented environment variable passing via -e flags on docker run command line
crates/prek/tests/languages/script.rs	Updated tests to use versioned repo and added tests demonstrating env variable functionality
crates/prek/tests/languages/docker.rs	Updated test to demonstrate env variable functionality with docker hooks
crates/prek/src/snapshots/prek__config__tests__read_manifest.snap	Updated snapshot to include env: None in hook definitions
crates/prek/src/snapshots/prek__config__tests__read_config.snap	Updated snapshot to include env: None in hook configurations

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[j178]

Thank you, great PR!