allow changing log filtering while node runs

This also changes the default to tracing-subscriber.

1 files changed, 27 insertions, 0 deletions

diff --git a/src/api/log.rs b/src/api/log.rs
new file mode 100644
index 0000000..4881b38
--- /dev/null
+++ b/src/api/log.rs
@@ -0,0 +1,27 @@
+//! /admin/log: read and replace the log filter of the running node.
+
+use axum::{body::Bytes, http::StatusCode};
+use tracing::{info, warn};
+
+use crate::logging;
+
+/// `GET /admin/log`: the filter in effect, as plain text in `RUST_LOG` syntax.
+pub(crate) async fn get_log_filter() -> Result<String, StatusCode> {
+    logging::filter().map_err(|error| {
+        warn!(error = %format!("{error:#}"), "Cannot read the log filter");
+        StatusCode::INTERNAL_SERVER_ERROR
+    })
+}
+
+/// `PUT /admin/log`: replace the filter; the body is plain text in `RUST_LOG` syntax,
+/// e.g. `info,continuum::swarm::sync=trace`. Answers with the filter now in effect;
+/// 400 (with the reason) if the body doesn't parse, and the old filter stays.
+pub(crate) async fn put_log_filter(body: Bytes) -> Result<String, (StatusCode, String)> {
+    let directives = std::str::from_utf8(&body)
+        .map_err(|_| (StatusCode::BAD_REQUEST, "The filter must be UTF-8\n".to_owned()))?
+        .trim();
+    let applied = logging::set_filter(directives)
+        .map_err(|error| (StatusCode::BAD_REQUEST, format!("{error:#}\n")))?;
+    info!(filter = %applied, "Log filter replaced");
+    Ok(applied + "\n")
+}