cli_rs: set up debug logging

Summary: This diff sets up debug logging for EdenFS CLI with tracing.

Reviewed By: chadaustin

Differential Revision: D26354205

fbshipit-source-id: bcc89fe3eaf4c7ae7642b8c20fd74fd3ea6dd4ee

eden/fs/cli_rs/edenfs-commands/src/lib.rs

@@ -10,6 +10,7 @@ use std::path::PathBuf;
 use anyhow::{Context, Result};
 use structopt::{clap::AppSettings, StructOpt};
 use tokio_compat_02::FutureExt;
+use tracing::{event, Level};
 
 use edenfs_client::EdenFsInstance;
 use util::path::expand_path;
@@ -45,6 +46,9 @@ pub struct Command {
     #[structopt(long, parse(from_str = expand_path))]
     home_dir: Option<PathBuf>,
 
+    #[structopt(long)]
+    pub debug: bool,
+
     #[structopt(subcommand)]
     subcommand: SubCommand,
 }
@@ -85,6 +89,8 @@ impl Command {
     /// Execute subcommands. This function returns only a return code since all the error handling
     /// should be taken care of by each sub-command.
     async fn dispatch(self) -> ExitCode {
+        event!(Level::TRACE, cmd = ?self, "Dispatching");
+
         let instance = self.get_instance();
         match self.subcommand {
             SubCommand::Status(status) => status.run(instance).await,

eden/fs/cli_rs/edenfsctl/src/main.rs

@@ -11,6 +11,7 @@ use std::process::Command;
 
 use anyhow::{anyhow, Context, Result};
 use structopt::StructOpt;
+use tracing_subscriber::filter::EnvFilter;
 
 fn python_fallback() -> Result<Command> {
     if let Ok(args) = std::env::var("EDENFSCTL_REAL") {
@@ -53,10 +54,30 @@ fn fallback() -> Result<()> {
     }
 }
 
+/// Setup tracing logging. If we are in development mode, we use the fancier logger, otherwise a
+/// simple logger for production use. Logs will be printined to stderr when `--debug` flag is
+/// passed.
+fn setup_logging() {
+    let subscriber = tracing_subscriber::fmt();
+    #[cfg(debug_assertions)]
+    let subscriber = subscriber.pretty();
+    let subscriber = subscriber.with_env_filter(EnvFilter::from_env("EDENFS_LOG"));
+
+    if let Err(e) = subscriber.try_init() {
+        eprintln!(
+            "Unable to initialize logger. Logging will be disabled. Cause: {:?}",
+            e
+        );
+    }
+}
+
 fn main() -> Result<()> {
     if std::env::var("EDENFSCTL_SKIP_RUST").is_ok() {
         fallback()
     } else if let Ok(cmd) = edenfs_commands::Command::from_args_safe() {
+        if cmd.debug {
+            setup_logging();
+        }
         match cmd.run() {
             Ok(code) => std::process::exit(code),
             Err(e) => Err(e),