support Deno auto installation by janosh · Pull Request #968 · j178/prek

janosh · 2025-10-26T09:45:20Z

deno language support for pre-commit hooks with automatic version management from GitHub releases.

Features:

Auto-downloads requested Deno versions or uses system installation (if version matches)
Supports language_version (exact, semver ranges) and additional_dependencies (npm:, jsr:)
Creates isolated DENO_DIR for dependency caching
Cross-platform support (Linux, macOS, Windows)

Changes:

Add DenoInstaller, DenoVersion, and DenoRequest for version management
Add Deno to storage buckets and language registry
Add 8 comprehensive tests
Update documentation

Mirrors Node.js/Go installation patterns for consistency.

- Implement Deno language handler with dependency isolation - Support npm packages via `additional_dependencies` - Add 8 tests covering basic usage, dependencies, and error cases - example config showing deno fmt, lint, and npm eslint hook usage

Implement full-fledged Deno language support with automatic version management, mirroring the installation patterns used for Node.js and Go. - **installer.rs**: New DenoInstaller that downloads and installs Deno versions - Downloads from GitHub releases (https://github.com/denoland/deno/releases) - Searches installed versions in $PREK_HOME/tools/deno - Falls back to system Deno if version matches - Supports all platforms: Linux, macOS, Windows (x86_64, aarch64) - Uses file locking to prevent concurrent installations - Implements proper binary extraction and permission setup - **version.rs**: New DenoVersion and DenoRequest types - Supports version specifications: exact (1.40.0), major (1), major.minor (1.40) - Supports semver ranges: ">= 1.40, < 1.50" - Handles "deno", "deno@version", "latest", "system" formats - Supports local path specifications - Comprehensive unit tests for version parsing - **deno.rs**: Updated to use DenoInstaller - Removed manual system-only detection - Integrated with DenoInstaller for automatic downloads - Simplified installation flow - Proper health checks with version validation

codecov · 2025-10-26T09:48:17Z

Codecov Report

❌ Patch coverage is 79.62185% with 97 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.59%. Comparing base (987923c) to head (4c5e205).
⚠️ Report is 1 commits behind head on deno.

Files with missing lines	Patch %	Lines
src/languages/deno/installer.rs	75.78%	46 Missing ⚠️
src/languages/deno/version.rs	78.64%	22 Missing ⚠️
src/languages/deno/deno.rs	85.88%	12 Missing ⚠️
src/languages/mod.rs	81.53%	12 Missing ⚠️
src/languages/version.rs	0.00%	3 Missing ⚠️
src/languages/python/uv.rs	90.90%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             deno     #968      +/-   ##
==========================================
+ Coverage   83.58%   89.59%   +6.00%     
==========================================
  Files          67       69       +2     
  Lines       12352    12680     +328     
==========================================
+ Hits        10325    11361    +1036     
+ Misses       2027     1319     -708

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j178 · 2025-10-26T10:01:35Z

wow!

* Update language support status * Tweak

github-actions · 2025-10-26T10:52:34Z

📦 Cargo Bloat Comparison

Binary size change: +0.62% (16.1 MiB → 16.2 MiB)

Expand for cargo-bloat output

PR Branch Results

 File  .text     Size          Crate Name
 0.6%   1.3% 101.1KiB          prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.6%   1.3%  97.2KiB           prek prek::languages::<impl prek::config::Language>::run::{{closure}}
 0.5%   1.1%  85.8KiB           prek prek::builtin::pre_commit_hooks::Implemented::run::{{closure}}
 0.4%   0.9%  70.0KiB           prek prek::run::{{closure}}
 0.4%   0.8%  63.8KiB           prek prek::archive::unpack::{{closure}}
 0.3%   0.6%  46.8KiB           prek prek::languages::<impl prek::config::Language>::install::{{closure}}
 0.2%   0.5%  40.9KiB regex_automata regex_automata::meta::strategy::new
 0.2%   0.5%  40.1KiB          prek? <prek::cli::RunArgs as clap_builder::derive::Args>::augment_args
 0.2%   0.5%  38.5KiB           prek prek::identify::by_extension::{{closure}}
 0.2%   0.4%  32.9KiB           prek prek::workspace::Workspace::discover
 0.2%   0.4%  32.8KiB           prek prek::cli::run::run::run::{{closure}}
 0.2%   0.4%  31.8KiB             h2 h2::proto::connection::DynConnection<B>::recv_frame
 0.2%   0.4%  31.7KiB             h2 h2::proto::connection::Connection<T,P,B>::poll
 0.2%   0.4%  30.4KiB           prek prek::languages::node::installer::NodeInstaller::install::{{closure}}
 0.2%   0.4%  27.0KiB           prek prek::languages::deno::installer::DenoInstaller::install::{{closure}}
 0.2%   0.3%  26.2KiB     hyper_util hyper_util::client::legacy::client::Client<C,B>::send_request::{{closure}}
 0.2%   0.3%  25.8KiB     hyper_util hyper_util::client::legacy::client::Client<C,B>::connect_to::{{closure}}::{{closure}}::{{closure}}
 0.2%   0.3%  25.0KiB        globset globset::GlobSetBuilder::build
 0.2%   0.3%  25.0KiB           prek prek::main
 0.1%   0.3%  24.2KiB           prek prek::languages::golang::installer::GoInstaller::install::{{closure}}
39.7%  87.2%   6.4MiB                And 10220 smaller methods. Use -n N to show more.
45.5% 100.0%   7.4MiB                .text section size, the file size is 16.2MiB

Base Branch Results

 File  .text     Size          Crate Name
 0.6%   1.3% 101.1KiB          prek? <prek::cli::Command as clap_builder::derive::Subcommand>::augment_subcommands
 0.6%   1.3%  96.2KiB           prek prek::languages::<impl prek::config::Language>::run::{{closure}}
 0.5%   1.1%  85.8KiB           prek prek::builtin::pre_commit_hooks::Implemented::run::{{closure}}
 0.4%   0.9%  70.0KiB           prek prek::run::{{closure}}
 0.4%   0.9%  63.8KiB           prek prek::archive::unpack::{{closure}}
 0.3%   0.6%  45.5KiB           prek prek::languages::<impl prek::config::Language>::install::{{closure}}
 0.2%   0.5%  40.9KiB regex_automata regex_automata::meta::strategy::new
 0.2%   0.5%  40.1KiB          prek? <prek::cli::RunArgs as clap_builder::derive::Args>::augment_args
 0.2%   0.5%  38.5KiB           prek prek::identify::by_extension::{{closure}}
 0.2%   0.4%  32.9KiB           prek prek::workspace::Workspace::discover
 0.2%   0.4%  32.8KiB           prek prek::cli::run::run::run::{{closure}}
 0.2%   0.4%  32.7KiB           prek prek::languages::node::installer::NodeInstaller::install::{{closure}}
 0.2%   0.4%  31.8KiB             h2 h2::proto::connection::DynConnection<B>::recv_frame
 0.2%   0.4%  31.7KiB             h2 h2::proto::connection::Connection<T,P,B>::poll
 0.2%   0.3%  26.2KiB     hyper_util hyper_util::client::legacy::client::Client<C,B>::send_request::{{closure}}
 0.2%   0.3%  25.8KiB     hyper_util hyper_util::client::legacy::client::Client<C,B>::connect_to::{{closure}}::{{closure}}::{{closure}}
 0.2%   0.3%  25.0KiB        globset globset::GlobSetBuilder::build
 0.2%   0.3%  25.0KiB           prek prek::main
 0.1%   0.3%  24.6KiB           prek prek::languages::golang::installer::GoInstaller::install::{{closure}}
 0.1%   0.3%  23.7KiB          hyper hyper::proto::h1::dispatch::Dispatcher<D,Bs,I,T>::poll_loop
39.6%  87.1%   6.4MiB                And 10145 smaller methods. Use -n N to show more.
45.4% 100.0%   7.3MiB                .text section size, the file size is 16.1MiB

j178 · 2025-10-26T11:01:30Z

src/languages/deno/deno.rs

+                    fs_err::tokio::copy(repo_deno_json, &deno_json).await?;
+                    needs_deno_json = false;
+                }
+                // Deno can run scripts directly from the repo without installation


I think we need to cache dependencies from deno.json (by deno install?). The idea is that install should set up everything needed for the hooks to run, so when we call run, it can work completely offline.

not an expert of deno, just a user. but i think deno maintains it's own global cache of every package that was ever imported in an executed script (be it from NPM, JSR or directly via URL from GitHub)

i guess we can call deno cache during hook installation. subtle benefit of that:

with deno cache: Dependencies are downloaded during prek install (slower install, faster first run, can detect dependency issues early)

without deno cache: Dependencies are downloaded on first hook run (faster install, slightly slower first run)

* Fail windows CI when an error occured * Fix tests

j178 · 2025-10-26T11:13:03Z

tests/languages/deno.rs

+    "#);
+}
+
+/// Test that when deno is not available, a helpful error is shown.


deno will be installed automatically, right?

j178 · 2025-10-26T11:17:01Z

src/languages/deno/deno.rs

+            // Replace "deno" with the actual path to the installed deno binary
+            let command = if entry[0] == "deno" {
+                deno_bin.as_path()
+            } else {
+                Path::new(&entry[0])
+            };


How about symlinking the deno executable into the hook env bin dir and prepending that bin dir to PATH, like we did in the node implementation? That might work better than this approach. For example, it would work for cases like entry: ./run_deno.sh.

If you agree, I can take care of it.

addresses #968 (comment)

…H resolution - Create bin/ directory in hook environment with symlinked deno executable - Prepend bin/ to PATH during install and run, matching Node implementation - Use entry.resolve() to find commands in PATH instead of manual replacement - Enables shell scripts to call `deno` directly with correct isolated version - add test verifying deno is available in PATH for shell scripts addresses #968 (comment)

- Simplify find_script_to_cache() using functional approach - Fix is_cacheable_script() to only match JS/TS files (prevents caching shell scripts) - Add support for .mjs, .tsx, .jsx extensions - Extract deno_bin variable to reduce duplication - Consolidate PATH setup to single location - Simplify deno.json creation logic - Add deno cache call during install for offline hook execution

janosh · 2025-10-27T11:32:55Z

btw, feel free to make changes as you see fit in this PR. i'm outside my comfort area here and may have made stupid mistakes so everything is up for scrutiny. also, feel free to merge this PR into the deno branch and continue work there

j178 · 2025-10-28T04:39:33Z

I'm going to merge this into deno branch and continue there, thank you!

* Do not check for `script` subprocess status (#964) * Update README * Allow using system trusted store by `PREK_NATIVE_TLS` (#959) * Fix compatibility with older luarocks (#967) * support isolated hook environments for `language: deno` - Implement Deno language handler with dependency isolation - Support npm packages via `additional_dependencies` - Add 8 tests covering basic usage, dependencies, and error cases - example config showing deno fmt, lint, and npm eslint hook usage * support Deno auto installation Implement full-fledged Deno language support with automatic version management, mirroring the installation patterns used for Node.js and Go. - **installer.rs**: New DenoInstaller that downloads and installs Deno versions - Downloads from GitHub releases (https://github.com/denoland/deno/releases) - Searches installed versions in $PREK_HOME/tools/deno - Falls back to system Deno if version matches - Supports all platforms: Linux, macOS, Windows (x86_64, aarch64) - Uses file locking to prevent concurrent installations - Implements proper binary extraction and permission setup - **version.rs**: New DenoVersion and DenoRequest types - Supports version specifications: exact (1.40.0), major (1), major.minor (1.40) - Supports semver ranges: ">= 1.40, < 1.50" - Handles "deno", "deno@version", "latest", "system" formats - Supports local path specifications - Comprehensive unit tests for version parsing - **deno.rs**: Updated to use DenoInstaller - Removed manual system-only detection - Integrated with DenoInstaller for automatic downloads - Simplified installation flow - Proper health checks with version validation * Update language support status (#970) * Update language support status * Tweak * Fix DenoRequest parsing * Generate cli reference * Fail windows CI when an error occured (#971) * Fail windows CI when an error occured * Fix tests * Use global client * delete outdated test, deno auto-installs after 2nd commit addresses j178/prek#968 (comment) * refactor(deno): symlink deno executable into hook bin dir and use PATH resolution - Create bin/ directory in hook environment with symlinked deno executable - Prepend bin/ to PATH during install and run, matching Node implementation - Use entry.resolve() to find commands in PATH instead of manual replacement - Enables shell scripts to call `deno` directly with correct isolated version - add test verifying deno is available in PATH for shell scripts addresses j178/prek#968 (comment) * refactor(deno): simplify install logic and add dependency caching - Simplify find_script_to_cache() using functional approach - Fix is_cacheable_script() to only match JS/TS files (prevents caching shell scripts) - Add support for .mjs, .tsx, .jsx extensions - Extract deno_bin variable to reduce duplication - Consolidate PATH setup to single location - Simplify deno.json creation logic - Add deno cache call during install for offline hook execution --------- Co-authored-by: Jo <10510431+j178@users.noreply.github.com> Co-authored-by: Steven Taylor <steven@taylormuff.co.uk>

j178 and others added 6 commits October 25, 2025 01:24

Do not check for script subprocess status (#964)

f36d12d

Update README

a25ecfd

Allow using system trusted store by PREK_NATIVE_TLS (#959)

7161581

Fix compatibility with older luarocks (#967)

76093da

janosh changed the base branch from master to deno October 26, 2025 09:45

j178 added 2 commits October 26, 2025 18:25

Update language support status (#970)

473ca4a

* Update language support status * Tweak

Fix DenoRequest parsing

08fac4e

Generate cli reference

a034a86

j178 reviewed Oct 26, 2025

View reviewed changes

j178 added 3 commits October 26, 2025 19:04

Fail windows CI when an error occured (#971)

b6c6ba8

* Fail windows CI when an error occured * Fix tests

Merge branch 'master' into deno

5909048

Use global client

0db0572

j178 reviewed Oct 26, 2025

View reviewed changes

janosh added 3 commits October 26, 2025 12:57

delete outdated test, deno auto-installs after 2nd commit

488d803

addresses #968 (comment)

j178 merged commit be74a68 into j178:deno Oct 28, 2025
18 of 21 checks passed

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support Deno auto installation#968

support Deno auto installation#968
j178 merged 15 commits intoj178:denofrom
janosh:deno

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