Configuration and logging improvements to logrotate_fs

This commit involves minor tweaks to the logrotate_fs to improve logging
and the configuration of said generator. Also I include an example
config.

Signed-off-by: Brian L. Troutwine <brian.troutwine@datadoghq.com>

examples/lading-logrotatefs.yaml

@@ -0,0 +1,17 @@
+generator:
+  - file_gen:
+      logrotate_fs:
+        seed: [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53,
+               59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131]
+        concurrent_logs: 8
+        maximum_bytes_per_log: 100MB
+        total_rotations: 4
+        max_depth: 0
+        variant: "ascii"
+        bytes_per_second: 10MB
+        maximum_prebuild_cache_size_bytes: 1GB
+        mount_point: /tmp/logrotate
+
+blackhole:
+  - tcp:
+      binding_addr: "0.0.0.0:8080"

lading/src/generator/file_gen/logrotate_fs.rs

@@ -22,7 +22,7 @@ use std::{
     time::Duration,
 };
 use tokio::task::{self, JoinError};
-use tracing::{error, info};
+use tracing::{debug, error, info};
 
 mod model;
 
@@ -123,6 +123,10 @@ impl Server {
             config.concurrent_logs,
         );
 
+        info!(
+            "Creating logrotate filesystem with mount point {mount}",
+            mount = config.mount_point.display(),
+        );
         // Initialize the FUSE filesystem
         let fs = LogrotateFS {
             state: Arc::new(Mutex::new(state)),
@@ -243,7 +247,7 @@ impl Filesystem for LogrotateFS {
         let name_str = name.to_str().unwrap_or("");
         if let Some(ino) = state.lookup(tick, parent as usize, name_str) {
             if let Some(attr) = getattr_helper(&mut state, self.start_time_system, tick, ino) {
-                info!("lookup: returning attr for inode {}: {:?}", ino, attr);
+                debug!("lookup: returning attr for inode {}: {:?}", ino, attr);
                 reply.entry(&TTL, &attr, 0);
                 return;
             }

lading/src/generator/file_gen/logrotate_fs/model.rs

@@ -402,7 +402,11 @@ impl State {
 
         for group_id in 0..num_groups {
             let mut current_inode = state.root_inode;
-            let depth = rng.gen_range(1..=max_depth as usize);
+            let depth = if max_depth == 0 {
+                0
+            } else {
+                rng.gen_range(1..=max_depth as usize)
+            };
 
             // Build the directory path
             for _ in 0..depth {