Expose runtime dependencies of Nix package properly

hooks/backend_exec_env.lua

@@ -14,6 +14,12 @@ function PLUGIN:BackendExecEnv(ctx)
         { key = "PATH", value = bin_path },
     }
 
+    local runtime_deps = require("lib.runtime_deps")
+    local runtime_dep_env_vars = runtime_deps.get_env_vars(install_path, tool, version, RUNTIME.osType)
+    for _, env_var in ipairs(runtime_dep_env_vars) do
+        table.insert(env_vars, env_var)
+    end
+
     if tool == "ruby" then
         -- Nix store is read-only, gems should be installed to the state dir
         table.insert(env_vars, { key = "GEM_HOME", value = file.join_path(install_path, "state/gems") })

lib/runtime_deps.lua

@@ -0,0 +1,108 @@
+local M = {}
+
+-- The main Nix package has runtime deps (other Nix store objects), which provide the usual
+-- C headers, shared libraries and pkgconfig files. This function queries those runtime deps
+-- and constructs the necessary env vars to make those dependencies available at runtime.
+-- In practice, this is important when running package manager binaries that try to build native code
+-- (e.g. Ruby gems that compile C extensions).
+function M.get_env_vars(install_path, tool, version, os_type)
+    local file = require("file")
+    local cmd = require("cmd")
+
+    local result_path = file.join_path(install_path, "result")
+    local requisites = cmd.exec("nix-store --query --requisites " .. result_path)
+
+    if requisites:match("error") or requisites:match("failed") then
+        error("Failed to query runtime deps for " .. tool .. "@" .. version .. ": " .. requisites)
+    end
+
+    local store_paths = {}
+    for store_path in string.gmatch(requisites, "[^%s]+") do -- poor man's strings.Split(requisites, "\n")
+        table.insert(store_paths, store_path)
+    end
+
+    local lib_paths = M.find_lib_paths(store_paths, file, cmd)
+    local pkgconfig_paths = M.find_pkgconfig_paths(store_paths, file, cmd)
+
+    local env_vars = {}
+    local lib_env_vars = M.create_library_env_vars(lib_paths, os_type)
+    local pkgconfig_env_vars = M.create_pkgconfig_env_vars(pkgconfig_paths)
+
+    for _, var in ipairs(lib_env_vars) do
+        table.insert(env_vars, var)
+    end
+    for _, var in ipairs(pkgconfig_env_vars) do
+        table.insert(env_vars, var)
+    end
+
+    return env_vars
+end
+
+-- TODO: file.exists() doesn't exist 🤷
+-- https://github.com/jdx/mise/pull/6754
+-- Can be replaced once our pinned mise version is bumped again
+function M.dir_exists(path, cmd_module)
+    local check_cmd = "if [ -d " .. path .. " ]; then echo 'exists'; fi"
+    local check_output = cmd_module.exec(check_cmd)
+    return check_output:match("exists") ~= nil
+end
+
+-- Finds all lib directories in the given store paths
+function M.find_lib_paths(store_paths, file_module, cmd_module)
+    local lib_paths = {}
+    for _, store_path in ipairs(store_paths) do
+        local lib_path = file_module.join_path(store_path, "lib")
+        if M.dir_exists(lib_path, cmd_module) then
+            table.insert(lib_paths, lib_path)
+        end
+    end
+    return lib_paths
+end
+
+-- Finds all lib/pkgconfig directories in the given store paths
+function M.find_pkgconfig_paths(store_paths, file_module, cmd_module)
+    local pkgconfig_paths = {}
+    for _, store_path in ipairs(store_paths) do
+        local pkgconfig_path = file_module.join_path(store_path, "lib/pkgconfig")
+        if M.dir_exists(pkgconfig_path, cmd_module) then
+            table.insert(pkgconfig_paths, pkgconfig_path)
+        end
+    end
+    return pkgconfig_paths
+end
+
+-- Exposes shared library paths for the (platform-specific) dynamic linker
+function M.create_library_env_vars(lib_paths, os_type)
+    local env_vars = {}
+    local key = nil
+
+    if os_type == "linux" then
+        key = "LD_LIBRARY_PATH"
+    elseif os_type == "darwin" then
+        key = "DYLD_LIBRARY_PATH"
+    else
+        error("Unsupported architecture: " .. os_type)
+    end
+
+    for _, lib_path in ipairs(lib_paths) do
+		local is_linux_glibc = os_type == "linux" and lib_path:match("glibc")
+		local is_darwin_llvm = os_type == "darwin" and (lib_path:match("llvm") or lib_path:match("clang"))
+		local is_linux_libyaml = os_type == "linux" and lib_path:match("libyaml")
+		-- if not is_linux_glibc and not is_darwin_llvm then
+		if is_linux_libyaml then
+			table.insert(env_vars, { key = key, value = lib_path })
+		end
+    end
+
+    return env_vars
+end
+
+function M.create_pkgconfig_env_vars(pkgconfig_paths)
+    local env_vars = {}
+    for _, pkgconfig_path in ipairs(pkgconfig_paths) do
+        table.insert(env_vars, { key = "PKG_CONFIG_PATH", value = pkgconfig_path })
+    end
+    return env_vars
+end
+
+return M

mise-tasks/test-integration

@@ -84,12 +84,33 @@ run_test "PATH is set correctly" \
 run_test "GEM_HOME is set for ruby" \
     "mise exec nixpkgs:ruby@latest -- bash -c 'test -n \"\$GEM_HOME\"'" || exit 1
 
+echo ""
+echo "=== Gem Install Tests ==="
+
 run_test "ruby: gem install fastlane" \
     "mise exec nixpkgs:ruby@latest -- gem install fastlane" || exit 1
 
 run_test "ruby: gem install cocoapods" \
     "mise exec nixpkgs:ruby@latest -- gem install cocoapods" || exit 1
 
+# Needs libyaml from system libraries
+run_test "ruby: gem install psych" \
+    "mise exec nixpkgs:ruby@latest -- gem install psych" || exit 1
+
+run_test "ruby: gem install psych: build from source" \
+    "mise exec nixpkgs:ruby@latest -- gem install psych --platform ruby" || exit 1
+
+cleanup_installs
+
+echo ""
+echo "=== Smoke Tests ==="
+
+run_test "fastlane actions" \
+    "mise exec nixpkgs:ruby@latest -- bash -c 'gem install fastlane && fastlane actions'" || exit 1
+
+run_test "pod plugins" \
+    "mise exec nixpkgs:ruby@latest -- bash -c 'gem install cocoapods && pod plugins --allow-root'" || exit 1
+
 cleanup_installs
 
 echo ""

mise.toml

@@ -17,7 +17,7 @@ run = "command -v busted >/dev/null 2>&1 || mise exec lua -- luarocks install bu
 
 [tasks.format]
 description = "Format Lua scripts"
-run = "stylua metadata.lua hooks/"
+run = "stylua metadata.lua hooks/ lib/ spec/"
 
 [tasks.lint]
 description = "Lint Lua scripts and GitHub Actions using hk"

spec/helpers/fixtures.lua

@@ -1,41 +1,41 @@
 local M = {}
 
 M.sample_index = {
-	pkgs = {
-		ruby = {
-			["3.3.9"] = {
-				nixpkgs_commit = "abc123def456",
-				commit_timestamp = "2025-01-15T12:00:00+00:00",
-				store_paths = {
-					["x86_64-linux"] = "/nix/store/hash1-ruby-3.3.9",
-					["aarch64-darwin"] = "/nix/store/hash2-ruby-3.3.9",
-				},
-			},
-			["3.3.8"] = {
-				nixpkgs_commit = "def456abc789",
-				commit_timestamp = "2025-01-14T12:00:00+00:00",
-				store_paths = {
-					["x86_64-linux"] = "/nix/store/hash3-ruby-3.3.8",
-					-- Note: aarch64-darwin entry is intentionally missing for testing
-				},
-			},
-		},
-		python = {
-			["3.12.1"] = {
-				nixpkgs_commit = "ghi789jkl012",
-				commit_timestamp = "2025-01-16T12:00:00+00:00",
-				store_paths = {
-					["x86_64-linux"] = "/nix/store/hash4-python-3.12.1",
-					["aarch64-darwin"] = "/nix/store/hash5-python-3.12.1",
-				},
-			},
-		},
-	},
+    pkgs = {
+        ruby = {
+            ["3.3.9"] = {
+                nixpkgs_commit = "abc123def456",
+                commit_timestamp = "2025-01-15T12:00:00+00:00",
+                store_paths = {
+                    ["x86_64-linux"] = "/nix/store/hash1-ruby-3.3.9",
+                    ["aarch64-darwin"] = "/nix/store/hash2-ruby-3.3.9",
+                },
+            },
+            ["3.3.8"] = {
+                nixpkgs_commit = "def456abc789",
+                commit_timestamp = "2025-01-14T12:00:00+00:00",
+                store_paths = {
+                    ["x86_64-linux"] = "/nix/store/hash3-ruby-3.3.8",
+                    -- Note: aarch64-darwin entry is intentionally missing for testing
+                },
+            },
+        },
+        python = {
+            ["3.12.1"] = {
+                nixpkgs_commit = "ghi789jkl012",
+                commit_timestamp = "2025-01-16T12:00:00+00:00",
+                store_paths = {
+                    ["x86_64-linux"] = "/nix/store/hash4-python-3.12.1",
+                    ["aarch64-darwin"] = "/nix/store/hash5-python-3.12.1",
+                },
+            },
+        },
+    },
 }
 
 M.sample_json = function()
-	local json = require("json")
-	return json.encode(M.sample_index)
+    local json = require("json")
+    return json.encode(M.sample_index)
 end
 
 return M

spec/helpers/mock_modules.lua

@@ -1,36 +1,37 @@
 local M = {}
 
 function M.mock_file_module()
-	return {
-		read = function(path)
-			return '{"pkgs":{}}'
-		end,
-		join_path = function(...)
-			return table.concat({ ... }, "/")
-		end,
-	}
+    return {
+        read = function(path)
+            return '{"pkgs":{}}'
+        end,
+        join_path = function(...)
+            return table.concat({ ... }, "/")
+        end,
+    }
 end
 
 function M.mock_cmd_module()
-	return {
-		exec = function(cmd)
-			return "success"
-		end,
-	}
+    return {
+        exec = function(cmd)
+            return "success"
+        end,
+    }
 end
 
 function M.inject_modules(mocks)
-	for name, mock in pairs(mocks) do
-		package.loaded[name] = mock
-	end
+    for name, mock in pairs(mocks) do
+        package.loaded[name] = mock
+    end
 end
 
 function M.clear_modules()
-	package.loaded["file"] = nil
-	package.loaded["json"] = nil
-	package.loaded["cmd"] = nil
-	package.loaded["lib.nix"] = nil
-	package.loaded["lib.nixpkgs_mapping"] = nil
+    package.loaded["file"] = nil
+    package.loaded["json"] = nil
+    package.loaded["cmd"] = nil
+    package.loaded["lib.nix"] = nil
+    package.loaded["lib.nixpkgs_mapping"] = nil
+    package.loaded["lib.runtime_deps"] = nil
 end
 
 return M

spec/helpers/mock_runtime.lua

@@ -1,20 +1,20 @@
 local M = {}
 
 function M.create_runtime(opts)
-	opts = opts or {}
-	return {
-		osType = opts.osType or "linux",
-		archType = opts.archType or "amd64",
-		pluginDirPath = opts.pluginDirPath or "/tmp/test-plugin",
-	}
+    opts = opts or {}
+    return {
+        osType = opts.osType or "linux",
+        archType = opts.archType or "amd64",
+        pluginDirPath = opts.pluginDirPath or "/tmp/test-plugin",
+    }
 end
 
 function M.inject_runtime(runtime)
-	_G.RUNTIME = runtime
+    _G.RUNTIME = runtime
 end
 
 function M.restore_runtime()
-	_G.RUNTIME = nil
+    _G.RUNTIME = nil
 end
 
 return M