Support stderr log-limit restriciton for serve

As `just serve` is used like a daemon it can be desirable to restrict
stderr, e.g., to only errors, while keeping a detailled log of the
activity in a file.

2 files changed, 20 insertions, 3 deletions

diff --git a/share/man/just-serve-config.5.md b/share/man/just-serve-config.5.md
index 0612b181..4f127ea4 100644
--- a/share/man/just-serve-config.5.md
+++ b/share/man/just-serve-config.5.md
@@ -31,11 +31,11 @@ The configuration file is given by a JSON object.
  - The value for the key *`"logging"`* is a JSON object specifying logging
    options.  
    For subkey *`"files"`* the value is a list of strings specifying one or more
-   local log files to use. The files will store the information printed on
-   stderr, along with the thread id and timestamp when the output has been
-   generated.  
+   local log files to use.  
    For subkey *`"limit"`* the value is an integer setting the default for
    the log limit.  
+   For subkey *`"restrict stderr limit"`* the value is an integer setting a
+   restriction for the log on stderr.  
    For subkey *`"plain"`* the value is a flag. If set, do not use ANSI escape
    sequences to highlight messages.  
    For subkey *`"append"`* the value is a flag. If set, append messages to log
diff --git a/src/buildtool/main/serve.cpp b/src/buildtool/main/serve.cpp
index 9dc4d936..1c321c0b 100644
--- a/src/buildtool/main/serve.cpp
+++ b/src/buildtool/main/serve.cpp
@@ -239,6 +239,23 @@ void ReadJustServeConfig(gsl::not_null<CommandLineArguments*> const& clargs) {
             }
             clargs->log.log_limit = ToLogLevel(limit->Number());
         }
+        // read stderr restriction
+        auto stderr_limit =
+            logging->Get("restrict stderr limit", Expression::none_t{});
+        if (stderr_limit.IsNotNull()) {
+            if (not stderr_limit->IsNumber()) {
+                Logger::Log(
+                    LogLevel::Error,
+                    "In serve service config file {}:\nValue for logging key "
+                    "\"restrict stderr limit\" has to be numeric, but found {}",
+                    clargs->serve.config.string(),
+                    limit->ToString());
+                std::exit(kExitFailure);
+            }
+            clargs->log.restrict_stderr_log_limit =
+                ToLogLevel(stderr_limit->Number());
+        }
+        // read stderr restriction
     }
     // read client TLS authentication arguments
     auto auth_args = serve_config["authentication"];