log: set default log level to 'info', add product specific logging env var

Logging behaviour can be overridden by the {PMG,PVE}_LOG environment
variable.

This commit also disables styled output and  timestamps in log messages,
since we usually log to the journal anyway. The log output is configured
to match with other log messages in task logs.

Signed-off-by: Lukas Wagner <l.wagner@proxmox.com>

common/src/logger.rs

@@ -1,6 +1,14 @@
+use env_logger::{Builder, Env};
+use std::io::Write;
+
 /// Initialize logging. Should only be called once
-pub fn init() {
-    if let Err(e) = env_logger::try_init() {
+pub fn init(env_var_name: &str, default_log_level: &str) {
+    if let Err(e) = Builder::from_env(Env::new().filter_or(env_var_name, default_log_level))
+        .format(|buf, record| writeln!(buf, "{}: {}", record.level(), record.args()))
+        .write_style(env_logger::WriteStyle::Never)
+        .format_timestamp(None)
+        .try_init()
+    {
         eprintln!("could not set up env_logger: {e}");
     }
 }

pmg-rs/src/lib.rs

@@ -12,6 +12,6 @@ mod export {
 
     #[export]
     pub fn init() {
-        common::logger::init();
+        common::logger::init("PMG_LOG", "info");
     }
 }

pve-rs/src/lib.rs

@@ -14,6 +14,6 @@ mod export {
 
     #[export]
     pub fn init() {
-        common::logger::init();
+        common::logger::init("PVE_LOG", "info");
     }
 }