3 files changed, 39 insertions, 36 deletions
diff --git a/src/buildtool/execution_api/local/TARGETS b/src/buildtool/execution_api/local/TARGETS
index 2c848bf7..53b7f717 100644
--- a/src/buildtool/execution_api/local/TARGETS
+++ b/src/buildtool/execution_api/local/TARGETS
@@ -5,14 +5,9 @@
   , "deps":
     [ ["@", "fmt", "", "fmt"]
     , ["@", "json", "", "json"]
-    , ["@", "gsl", "", "gsl"]
-    , ["src/buildtool/common", "common"]
-    , ["src/buildtool/file_system", "file_system_manager"]
-    , ["src/buildtool/file_system", "object_type"]
     , ["src/buildtool/logging", "log_level"]
     , ["src/buildtool/logging", "logging"]
-    , ["src/buildtool/execution_api/remote", "config"]
-    , ["src/buildtool/compatibility", "compatibility"]
+    , ["src/utils/cpp", "expected"]
     ]
   , "stage": ["src", "buildtool", "execution_api", "local"]
   }
diff --git a/src/buildtool/execution_api/local/config.hpp b/src/buildtool/execution_api/local/config.hpp
index 92d6606a..f2c8bf57 100644
--- a/src/buildtool/execution_api/local/config.hpp
+++ b/src/buildtool/execution_api/local/config.hpp
@@ -15,49 +15,56 @@
 #ifndef INCLUDED_SRC_BUILDTOOL_EXECUTION_API_LOCAL_CONFIG_HPP
 #define INCLUDED_SRC_BUILDTOOL_EXECUTION_API_LOCAL_CONFIG_HPP
 
-#include <filesystem>
-#include <functional>
+#include <exception>
+#include <optional>
 #include <string>
+#include <utility>  // std::move
 #include <vector>
 
-#include "gsl/gsl"
+#include "fmt/core.h"
 #include "nlohmann/json.hpp"
-#include "src/buildtool/common/artifact_digest.hpp"
-#include "src/buildtool/file_system/file_system_manager.hpp"
-#include "src/buildtool/file_system/object_type.hpp"
 #include "src/buildtool/logging/log_level.hpp"
 #include "src/buildtool/logging/logger.hpp"
+#include "src/utils/cpp/expected.hpp"
 
-/// \brief Store global build system configuration.
-class LocalExecutionConfig {
+/// \brief Store local execution configuration.
+struct LocalExecutionConfig final {
+    class Builder;
+
+    // Launcher to be prepended to action's command before executed.
+    // Default: ["env", "--"]
+    std::vector<std::string> const launcher = {"env", "--"};
+};
+
+class LocalExecutionConfig::Builder final {
   public:
-    [[nodiscard]] static auto SetLauncher(
-        std::vector<std::string> const& launcher) noexcept -> bool {
-        try {
-            Instance().launcher_ = launcher;
-        } catch (std::exception const& e) {
-            Logger::Log(LogLevel::Error,
-                        "when setting the local launcher\n{}",
-                        e.what());
-            return false;
-        }
-        return true;
+    auto SetLauncher(std::vector<std::string> launcher) noexcept -> Builder& {
+        launcher_ = std::move(launcher);
+        return *this;
     }
 
-    [[nodiscard]] static auto GetLauncher() noexcept
-        -> std::vector<std::string> {
-        return Instance().launcher_;
-    }
+    /// \brief Finalize building and create LocalExecutionConfig.
+    /// \return LocalExecutionConfig on success, an error string on failure.
+    [[nodiscard]] auto Build() const noexcept
+        -> expected<LocalExecutionConfig, std::string> {
+        // To not duplicate default arguments in builder, create a default
+        // config and copy arguments from there.
+        LocalExecutionConfig const default_config;
+        auto launcher = default_config.launcher;
+        if (launcher_.has_value()) {
+            try {
+                launcher = *launcher_;
+            } catch (std::exception const& ex) {
+                return unexpected{
+                    fmt::format("Failed to set launcher:\n{}", ex.what())};
+            }
+        }
 
-    [[nodiscard]] static auto Instance() noexcept -> LocalExecutionConfig& {
-        static LocalExecutionConfig config;
-        return config;
+        return LocalExecutionConfig{.launcher = std::move(launcher)};
     }
 
   private:
-    // Launcher to be prepended to action's command before executed.
-    // Default: ["env", "--"]
-    std::vector<std::string> launcher_ = {"env", "--"};
+    std::optional<std::vector<std::string>> launcher_;
 };
 
 #endif  // INCLUDED_SRC_BUILDTOOL_EXECUTION_API_LOCAL_CONFIG_HPP
diff --git a/src/buildtool/execution_api/local/local_action.cpp b/src/buildtool/execution_api/local/local_action.cpp
index 73d78e36..b44fbd5c 100644
--- a/src/buildtool/execution_api/local/local_action.cpp
+++ b/src/buildtool/execution_api/local/local_action.cpp
@@ -165,7 +165,8 @@ auto LocalAction::Run(bazel_re::Digest const& action_id) const noexcept
         return std::nullopt;
     }
 
-    auto cmdline = exec_config_.GetLauncher();
+    // prepare actual command by including the launcher
+    auto cmdline = exec_config_.launcher;
     std::copy(cmdline_.begin(), cmdline_.end(), std::back_inserter(cmdline));
 
     SystemCommand system{"LocalExecution"};