[pbs-devel] [PATCH proxmox v2 2/4] log: add logger for perlmod crates

[Gabriel Goller]

Add logger for perlmod crates that always prints to stderr (with a
specific format, which will end up in the tasklog) and to journald.

Reported-by: Lukas Wagner <l.wagner at proxmox.com>
Signed-off-by: Gabriel Goller <g.goller at proxmox.com>
---
 proxmox-log/src/init.rs               | 29 ++++++++++++++++++++++++-
 proxmox-log/src/lib.rs                |  1 +
 proxmox-log/src/pve_task_formatter.rs | 31 +++++++++++++++++++++++++++
 3 files changed, 60 insertions(+), 1 deletion(-)
 create mode 100644 proxmox-log/src/pve_task_formatter.rs

diff --git a/proxmox-log/src/init.rs b/proxmox-log/src/init.rs
index 67efa9fcc81f..f2edcbec6a13 100644
--- a/proxmox-log/src/init.rs
+++ b/proxmox-log/src/init.rs
@@ -3,7 +3,8 @@ use tracing_log::{AsLog, LogTracer};
 use tracing_subscriber::{filter::filter_fn, layer::SubscriberExt, Layer};
 
 use crate::{
-    get_env_variable, journald_or_stderr_layer, plain_stderr_layer, tasklog_layer::TasklogLayer, LogContext
+    get_env_variable, journald_or_stderr_layer, plain_stderr_layer,
+    pve_task_formatter::PveTaskFormatter, tasklog_layer::TasklogLayer, LogContext,
 };
 
 /// Inits a new tracing logger that prints to journald or tasklog with the logging level specified in the
@@ -94,6 +95,32 @@ pub fn journald(env_var: &str, default_log_level: LevelFilter) -> Result<(), any
     Ok(())
 }
 
+/// Inits a new tracing logger that prints to stderr and journald with the logging level specified
+/// in the environment variable `env_var`.
+///
+/// Prints every message to stderr with a pve-specific format and journald (the fallback will be
+/// stderr as well). The output format for stderr will be "DEBUG: ...msg.." (equivalent to the
+/// pve-workertask format). If `env_var` does not exist or doesn't contain a readable log level,
+/// the `default_log_level` will be used.
+pub fn stderr_and_journald_with_pve_format(
+    env_var: &str,
+    default_log_level: LevelFilter,
+) -> Result<(), anyhow::Error> {
+    let log_level = get_env_variable(env_var, default_log_level);
+
+    let stderr_layer = tracing_subscriber::fmt::layer()
+        .event_format(PveTaskFormatter {})
+        .with_writer(std::io::stderr);
+
+    let registry = tracing_subscriber::registry()
+        .with(tracing_journald::layer().ok().with_filter(log_level))
+        .with(stderr_layer.with_filter(log_level));
+
+    tracing::subscriber::set_global_default(registry)?;
+    LogTracer::init_with_filter(log_level.as_log())?;
+    Ok(())
+}
+
 /// Inits a new tracing logger that prints to journald and tasklog with the logging level specified in the
 /// environment variable `env_var`.
 ///
diff --git a/proxmox-log/src/lib.rs b/proxmox-log/src/lib.rs
index 50f63699336f..f5e448fb7f79 100644
--- a/proxmox-log/src/lib.rs
+++ b/proxmox-log/src/lib.rs
@@ -12,6 +12,7 @@ use tracing_subscriber::filter::filter_fn;
 use tracing_subscriber::prelude::*;
 
 mod file_logger;
+mod pve_task_formatter;
 mod tasklog_layer;
 
 pub mod init;
diff --git a/proxmox-log/src/pve_task_formatter.rs b/proxmox-log/src/pve_task_formatter.rs
new file mode 100644
index 000000000000..e9866a4b0869
--- /dev/null
+++ b/proxmox-log/src/pve_task_formatter.rs
@@ -0,0 +1,31 @@
+use std::fmt;
+use tracing::{Event, Subscriber};
+use tracing_subscriber::field::VisitOutput;
+use tracing_subscriber::fmt::format::{DefaultVisitor, Writer};
+use tracing_subscriber::fmt::{FmtContext, FormatEvent, FormatFields};
+use tracing_subscriber::registry::LookupSpan;
+
+/// This custom formatter outputs logs as they are visible in the PVE task log.
+///
+/// e.g.: "DEBUG: sample message"
+pub struct PveTaskFormatter {}
+
+impl<C, N> FormatEvent<C, N> for PveTaskFormatter
+where
+    C: Subscriber + for<'a> LookupSpan<'a>,
+    N: for<'a> FormatFields<'a> + 'static,
+{
+    fn format_event(
+        &self,
+        _ctx: &FmtContext<'_, C, N>,
+        mut writer: Writer<'_>,
+        event: &Event<'_>,
+    ) -> fmt::Result {
+        write!(writer, "{}: ", event.metadata().level().as_str())?;
+
+        let mut v = DefaultVisitor::new(writer.by_ref(), true);
+        event.record(&mut v);
+        v.finish()?;
+        writer.write_char('\n')
+    }
+}
-- 
2.39.5