Add local launcher to just-serve config

As just serve can simultaneously act as remote-execution endpoint,
it has to accept in its configuration all the necessary information,
in particular, the local launcher. Add it.

2 files changed, 35 insertions, 1 deletions

diff --git a/share/man/just-serve-config.5.md b/share/man/just-serve-config.5.md
index 5dd02d08..c4ac8dee 100644
--- a/share/man/just-serve-config.5.md
+++ b/share/man/just-serve-config.5.md
@@ -107,7 +107,12 @@ The configuration file is given by a JSON object.
    remote-execution endpoint. The value *`"disable"`* disables
    adding new entries to the target-level cache, which defeats the
    purpose of typical set up to share target-level computations
-   between clients.
+   between clients.  
+   For the subkey *`"local launcher"`*, if given, the value has
+   to be a list. This list is used as local launcher for the
+   build in the case the serve process acts simultaneously as
+   remote-execution endpoint. If unset (or `null`), the value
+   `["env", "--"]` will be taken as default.
 
 
 See also
diff --git a/src/buildtool/main/serve.cpp b/src/buildtool/main/serve.cpp
index e2b6635e..cebbd247 100644
--- a/src/buildtool/main/serve.cpp
+++ b/src/buildtool/main/serve.cpp
@@ -524,6 +524,35 @@ void ReadJustServeConfig(gsl::not_null<CommandLineArguments*> const& clargs) {
             }
             clargs->tc.target_cache_write_strategy = *s_value;
         }
+
+        auto launcher = build_args->Get("local launcher", Expression::none_t{});
+        if (launcher.IsNotNull()) {
+            if (not launcher->IsList()) {
+                Logger::Log(
+                    LogLevel::Error,
+                    "In serve service config file {}:\nValue for build key "
+                    "\"local launcher\" has to be a list, but found {}",
+                    clargs->serve.config.string(),
+                    launcher->ToString());
+                std::exit(kExitFailure);
+            }
+            std::vector<std::string> launcher_list{};
+            for (auto const& entry : launcher->List()) {
+                if (not entry->IsString()) {
+                    Logger::Log(LogLevel::Error,
+                                "In serve service config file {}:\nValue for "
+                                "build key \"local launcher\" has to be a list "
+                                "of string, but found {} with entry {}",
+                                clargs->serve.config.string(),
+                                launcher->ToString(),
+                                entry->ToString());
+
+                    std::exit(kExitFailure);
+                }
+                launcher_list.emplace_back(entry->String());
+            }
+            clargs->build.local_launcher = launcher_list;
+        }
     }
 }