feat: runtime musl/glibc detection for correct libc variant selection by jdx · Pull Request #8490 · jdx/mise

jdx · 2026-03-07T01:43:20Z

Summary

Detect musl libc at runtime (by checking for /lib/ld-musl-*) instead of using compile-time cfg!(target_env = "musl"), so a musl-built mise on a glibc system (or vice versa) selects the correct artifact variant
Set the musl qualifier on Platform::current() for musl systems, propagating through get_platform_key() and AssetPicker for correct lockfile keys and asset selection
Add linux-x64-musl and linux-arm64-musl to common_platforms() so mise lock resolves checksums/URLs for both glibc and musl variants
Add github:snyk/cli as a fallback registry backend for snyk

How it works with mise.lock

The lockfile now stores separate entries for glibc and musl:

[tools.snyk.platforms.linux-x64]
checksum = "sha256:abc..."
url = "https://github.com/snyk/cli/releases/.../snyk-linux"

[tools.snyk.platforms.linux-x64-musl]
checksum = "sha256:def..."
url = "https://github.com/snyk/cli/releases/.../snyk-alpine"

At install time, the runtime-detected platform key selects the correct entry. Existing lockfiles without musl entries gracefully fall through to normal asset resolution.

Backward compatibility

Existing lockfiles with only linux-x64 keys continue to work — musl systems just resolve assets normally (no lockfile cache hit) until mise lock is re-run
Non-Linux platforms are unaffected
The platform_variants mechanism (already used by bun) allows backends to opt into generating musl-specific lockfile entries

Closes #8456

Test plan

All existing unit tests pass (platform, asset_matcher, lockfile)
Lint checks pass
Verify on Alpine Linux that Platform::current() returns linux-x64-musl
Verify on glibc Linux that Platform::current() returns linux-x64 (no qualifier)
Test mise use github:snyk/cli on both musl and glibc systems

🤖 Generated with Claude Code

Note

Medium Risk
Changes platform-keying and libc selection logic that affects lockfile lookups and which binaries are downloaded on Linux, so regressions could cause missed lockfile hits or wrong artifact selection on some distros.

Overview
Improves Linux libc handling by detecting musl at runtime and propagating it into Platform::current() so lockfile platform keys can include a -musl qualifier when appropriate.

Expands default lockfile targeting from 5 to 7 platforms by adding linux-*-musl entries, updates Backend::get_platform_key() to use Platform::current().to_key(), and adjusts AssetPicker to avoid using compile-time cfg!(target_env = "musl") so cross-platform locking doesn’t leak the host libc into other targets.

Updates the registry entry for snyk to include github:snyk/cli as an additional backend option, and refreshes the mise lock e2e test expectations accordingly.

^{Written by Cursor Bugbot for commit bd5f8d2. This will update automatically on new commits. Configure here.}

- Detect musl at runtime by checking for /lib/ld-musl-* instead of using compile-time cfg!(target_env = "musl"), so a musl-built mise on a glibc system (or vice versa) picks the correct artifact variant - Set qualifier on Platform::current() for musl systems so lockfile keys and asset selection use the right libc variant - Add linux-x64-musl and linux-arm64-musl to common_platforms() so mise lock resolves checksums/URLs for both glibc and musl variants - Update get_platform_key() to include the qualifier from Platform::current() - Add github:snyk/cli as a registry backend for snyk Closes #8456 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

gemini-code-assist · 2026-03-07T01:43:39Z

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances mise's ability to handle different C standard library (libc) environments on Linux. By switching from compile-time to runtime detection of musl libc, it ensures that mise can correctly identify and select appropriate tool artifacts, improving compatibility and reliability across diverse Linux distributions, especially those using musl like Alpine. This change also updates how platform keys are generated and stored in lockfiles, allowing for distinct entries for glibc and musl variants.

Highlights

Runtime Libc Detection: Implemented runtime detection for musl libc on Linux systems, replacing compile-time checks to ensure correct artifact variant selection regardless of how mise itself was built.
Platform Qualifier Propagation: Platform::current() now sets a musl qualifier for musl systems, which is propagated through get_platform_key() and AssetPicker for accurate lockfile keys and asset selection.
Expanded Common Platforms: Added linux-x64-musl and linux-arm64-musl to common_platforms() to enable mise lock to resolve checksums and URLs for both glibc and musl variants.
Snyk Registry Fallback: Included github:snyk/cli as an additional fallback registry backend for Snyk.

Changelog

registry/snyk.toml
- Added github:snyk/cli as a new backend for Snyk.
src/backend/asset_matcher.rs
- Modified AssetPicker::with_libc to determine the libc variant at runtime using Platform::current() instead of relying on the cfg!(target_env = "musl") compile-time flag.
src/backend/mod.rs
- Updated the default implementation of Backend::get_platform_key to use Platform::current().to_key(), ensuring that the libc qualifier (e.g., -musl) is included in the platform key.
src/platform.rs
- Updated Platform::current() to perform runtime detection of musl libc on Linux by checking for ld-musl-* in /lib, and sets the qualifier field accordingly.
- Introduced is_musl_system() function to encapsulate the logic for runtime musl detection.
- Expanded Platform::common_platforms() to include linux-x64-musl and linux-arm64-musl variants.
- Adjusted test_common_platforms to reflect the increased number of common platforms and assert the presence of the new musl variants.

Activity

All existing unit tests for platform, asset_matcher, and lockfile modules have passed.
Lint checks have passed.
Verification on Alpine Linux for Platform::current() returning linux-x64-musl is pending.
Verification on glibc Linux for Platform::current() returning linux-x64 is pending.
Testing mise use github:snyk/cli on both musl and glibc systems is pending.
The pull request was generated with Claude Code.

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Code Review

This pull request introduces runtime detection of musl libc on Linux systems, which is a significant improvement over the previous compile-time check. This allows mise binaries to correctly select libc-specific tool variants regardless of how mise itself was compiled. The changes are well-structured, propagating the detected libc variant through the Platform struct to asset selection and lockfile key generation. The addition of musl variants to common_platforms ensures lockfiles can be generated for both glibc and musl environments. I have one suggestion to make the musl detection logic more concise and idiomatic.

_{Note: Security Review is unavailable for this PR.}

gemini-code-assist · 2026-03-07T01:46:13Z

src/platform.rs

+        if let Ok(entries) = std::fs::read_dir("/lib") {
+            for entry in entries.flatten() {
+                if entry.file_name().to_string_lossy().starts_with("ld-musl-") {
+                    return true;
+                }
+            }
+        }
+        false


The logic for checking for musl can be made more concise and idiomatic by using iterator methods like any() and map() on the Result from read_dir.

std::fs::read_dir("/lib") .map(|entries| { entries.flatten().any(|entry| { entry .file_name() .to_string_lossy() .starts_with("ld-musl-") }) }) .unwrap_or(false)

src/backend/asset_matcher.rs

greptile-apps · 2026-03-07T01:50:32Z

Greptile Summary

This PR implements runtime musl/glibc detection on Linux so a glibc-compiled mise binary running on a musl system (e.g., Alpine) correctly selects musl-flavored artifacts. The implementation:

Detects musl by checking for glibc's dynamic linker (ld-linux-*) in /lib and /lib64 (if absent, confirms musl via ld-musl-* in /lib), replacing the previous ldd --version approach
Sets the musl qualifier in Platform::current() when running on musl, which propagates through get_platform_key() and AssetPicker for correct lockfile keys and asset selection
Expands common_platforms() from 5 to 7 entries with two new musl variants (linux-x64-musl, linux-arm64-musl) so mise lock captures both glibc and musl checksums
Defaults AssetPicker to gnu libc when unspecified (instead of compile-time musl detection) to avoid polluting cross-platform lockfile entries
Adds github:snyk/cli as a fallback registry backend for snyk

The runtime detection uses LazyLock for caching to avoid repeated filesystem checks. Existing lockfiles without musl entries continue to work due to is_compatible_with_current() matching by OS+arch only, providing graceful fallback until mise lock is re-run. All unit tests pass and e2e test_lock correctly verifies the 7 platform entries in lockfiles.

Confidence Score: 4/5

Safe to merge — runtime musl detection is correct and well-tested for primary use cases
The runtime musl/glibc detection implementation is sound. The code correctly uses filesystem checks to distinguish musl from glibc systems, with LazyLock caching to avoid repeated syscalls. Platform key generation properly incorporates the detected qualifier. The expansion of common_platforms to 7 entries (including musl variants) is correct. All existing tests pass and the test_lock updates verify the new lockfile entries are generated correctly. The implementation handles the main use case (Alpine Linux) correctly and maintains backward compatibility with existing lockfiles.
No files require special attention

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[Platform::current called] --> B{OS is linux?}
    B -- No --> C[qualifier = None]
    B -- Yes --> D[Runtime libc detection\ncached via LazyLock]
    D --> E{glibc linker found\nin /lib or /lib64?}
    E -- Yes --> F[qualifier = None\nglibc system]
    E -- No --> G{musl linker found\nin /lib?}
    G -- Yes --> H[qualifier = musl]
    G -- No --> I[qualifier = None\nunknown libc]
    C --> J[to_key returns os-arch]
    F --> J
    I --> J
    H --> K[to_key returns os-arch-musl]
    J --> L[Backend::get_platform_key]
    K --> L
    L --> M[Lockfile lookup\nby platform key]
    L --> N[AssetMatcher.for_target\npropagates qualifier as libc]
    M --> O{Cache hit?}
    O -- Yes --> P[Use stored URL and checksum]
    O -- No --> Q[Resolve via release API]

_{Last reviewed commit: bd5f8d2}

- Fix cross-platform lockfile bug: AssetPicker::with_libc now defaults to "gnu" when no qualifier is passed, instead of checking Platform::current(). This prevents `mise lock` on musl systems from incorrectly populating unqualified `linux-x64` entries with musl assets. - Add ToolVersion::get_lock_platform() fallback: when looking up a qualified key like `linux-x64-musl`, falls back to the unqualified `linux-x64` key. This maintains backward compatibility with existing lockfiles in --locked mode. - Update all lockfile read sites (github, java, locked-mode check) to use the new fallback method. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

jdx · 2026-03-07T01:57:48Z

@greptileai

src/backend/mod.rs

The aqua backend was still using tv.lock_platforms.get() directly instead of tv.get_lock_platform(), missing the fallback from qualified keys (linux-x64-musl) to unqualified keys (linux-x64) for pre-existing lockfiles. This caused --locked mode to pass validation but then fail to find the URL during aqua's actual install. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/toolset/tool_version.rs

Remove get_lock_platform() fallback from linux-x64-musl to linux-x64. On musl systems with old lockfiles, this fallback would silently install glibc binaries (which won't run) instead of either resolving fresh (normal mode) or erroring with a helpful "run mise lock" message (--locked mode). Both of those behaviors are correct and preferable to silently installing the wrong binary. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cursor

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

src/platform.rs

- Replace /lib/ld-musl-* file check with ldd --version output parsing. The ld-musl linker file can exist on glibc systems with musl-tools installed for cross-compilation, causing false positive detection. ldd --version reliably distinguishes: musl's ldd prints "musl libc", glibc's prints GNU version info. - Update e2e test_lock to expect 7 platforms (added musl variants). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Replace ldd --version subprocess with filesystem checks for the dynamic linker. glibc systems always have /lib[64]/ld-linux-*, even when musl-tools is installed for cross-compilation. Musl systems (Alpine, Void musl, etc.) only have /lib/ld-musl-* without ld-linux-*. Checking for the absence of glibc's linker first avoids false positives and is faster than spawning a subprocess. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

github-actions · 2026-03-07T02:45:34Z

Hyperfine Performance

`mise x -- echo`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`mise-2026.3.3 x -- echo`	24.5 ± 0.5	23.7	30.1	1.00
`mise x -- echo`	25.2 ± 0.9	23.6	30.3	1.03 ± 0.04

`mise env`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`mise-2026.3.3 env`	24.2 ± 0.8	22.9	29.3	1.00
`mise env`	25.4 ± 1.1	23.4	30.5	1.05 ± 0.06

`mise hook-env`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`mise-2026.3.3 hook-env`	25.1 ± 1.0	23.9	30.8	1.01 ± 0.04
`mise hook-env`	24.8 ± 0.4	23.8	26.7	1.00

`mise ls`

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`mise-2026.3.3 ls`	24.2 ± 0.9	23.2	32.4	1.00
`mise ls`	24.3 ± 0.7	23.1	27.3	1.00 ± 0.05

`xtasks/test/perf`

Command	mise-2026.3.3	mise	Variance
install (cached)	156ms	154ms	+1%
ls (cached)	85ms	84ms	+1%
bin-paths (cached)	88ms	87ms	+1%
task-ls (cached)	855ms	864ms	-1%

@iki

### 🚀 Features - **(github)** keep exe extensions on Windows by @iki in [#8424](#8424) - **(task)** add `interactive` field for exclusive terminal access by @jdx in [#8491](#8491) - add header comment to generated lockfiles by @ivy in [#8481](#8481) - runtime musl/glibc detection for correct libc variant selection by @jdx in [#8490](#8490) ### 🐛 Bug Fixes - **(github)** use registry platform options during install by @jdx in [#8492](#8492) - **(http)** store tool opts as native TOML to fix platform switching by @jdx in [#8448](#8448) - **(installer)** error if MISE_INSTALL_PATH is a directory by @jdx in [#8468](#8468) - **(prepare)** resolve sources/outputs relative to `dir` when set by @jdx in [#8472](#8472) - **(ruby)** fetch precompiled binary by release tag instead of listing all releases by @jdx in [#8488](#8488) - **(schema)** support structured objects in task depends by @risu729 in [#8463](#8463) - **(task)** replace println!/eprintln! with calm_io in task output macros by @vmaleze in [#8485](#8485) - handle scoped npm package names without backend prefix by @jdx in [#8477](#8477) ### 📦️ Dependency Updates - update ghcr.io/jdx/mise:copr docker digest to c485c4c by @renovate[bot] in [#8484](#8484) - update ghcr.io/jdx/mise:alpine docker digest to 8118bc7 by @renovate[bot] in [#8483](#8483) ### 📦 Registry - disable sd version test by @jdx in [#8489](#8489) ### New Contributors - @ivy made their first contribution in [#8481](#8481) - @iki made their first contribution in [#8424](#8424) ## 📦 Aqua Registry Updates #### New Packages (5) - [`datadog-labs/pup`](https://github.com/datadog-labs/pup) - [`k1LoW/mo`](https://github.com/k1LoW/mo) - [`rtk-ai/rtk`](https://github.com/rtk-ai/rtk) - [`suzuki-shunsuke/docfresh`](https://github.com/suzuki-shunsuke/docfresh) - [`yashikota/exiftool-go`](https://github.com/yashikota/exiftool-go) #### Updated Packages (6) - [`cloudflare/cloudflared`](https://github.com/cloudflare/cloudflared) - [`mozilla/sccache`](https://github.com/mozilla/sccache) - [`owenlamont/ryl`](https://github.com/owenlamont/ryl) - [`spinel-coop/rv`](https://github.com/spinel-coop/rv) - [`technicalpickles/envsense`](https://github.com/technicalpickles/envsense) - [`weaviate/weaviate`](https://github.com/weaviate/weaviate)

## Summary Expose the libc type detection added in #8490 to vfox plugins, in the `RUNTIME` global table. ## Details - Expose `RUNTIME.envType` to vfox Lua plugins (`"gnu"` for glibc Linux, `"musl"` for musl Linux, `nil` otherwise) - Add `env_type()` in `crates/vfox/src/config.rs` to detect libc at runtime via `/lib` and `/lib64` linker names - Add sync-note comments in `crates/vfox/src/config.rs` and `src/platform.rs` to keep both implementations aligned - Set `env_type` to `None` in `Runtime::with_platform()` because target libc is unknown for platform overrides - Document `RUNTIME.envType` in Lua types and plugin docs - Add missing `RUNTIME.version` and `RUNTIME.pluginDirPath` entries to `docs/tool-plugin-development.md` for parity ### Usage in plugins ```lua if RUNTIME.envType == "musl" then -- download musl-compatible binary elseif RUNTIME.envType == "gnu" then -- download glibc-compatible binary end ``` ## Design decisions We intentionally duplicate musl/glibc detection in `crates/vfox` because `vfox` is a separate crate boundary and sharing `is_musl_system()` would add unnecessary coupling. The logic is small, self-contained, and cross-referenced by sync notes in both locations to reduce drift. ## Test plan - [x] Unit tests for `env_type()` return only valid values (`"gnu"`, `"musl"`, or `nil`) on Linux and `nil` on non-Linux - [x] Added regression test ensuring `RUNTIME.envType` is `nil` when using platform override (`Runtime::with_platform`) - [x] `cargo test` passes - [x] Lint passes (`mise --cd crates/vfox run lint-fix`) 🤖 This PR description was generated with the assistance of Claude Opus 4.6.

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jdx and others added 2 commits March 7, 2026 02:22

jdx enabled auto-merge (squash) March 7, 2026 02:36

jdx merged commit 08d3971 into main Mar 7, 2026
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jdx deleted the feat/runtime-musl-detection branch March 7, 2026 02:39

mise-en-dev mentioned this pull request Mar 7, 2026

chore: release 2026.3.4 #8469

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mise 2026.3.4 Homebrew/homebrew-core#271077

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feat(vfox): add RUNTIME.envType for libc variant detection #8493

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feat: runtime musl/glibc detection for correct libc variant selection#8490

feat: runtime musl/glibc detection for correct libc variant selection#8490
jdx merged 6 commits intomainfrom
feat/runtime-musl-detection

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Confidence Score: 4/5

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