Do not transmit pid 0 as the target pid (#1087)

### What does this PR do?

In some cases docker will report that the pid of a new container is 0.
This is not a usable pid and we believe it is a race condition. Loop
around again in this even, logging.

Author: blt

CHANGELOG.md

@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+### Fixed
+- Target pid watcher will not report 0 for containers.
+
 ## [0.23.4]
 ### Added
 - Introduced logrotate_fs, a sub-generator of `file_gen` that exposes a FUSE

lading/src/target.rs

@@ -261,6 +261,17 @@ impl Server {
         let pid: i64 = loop {
             if let Ok(container) = docker.inspect_container(&config.name, None).await {
                 if let Some(pid) = container.state.and_then(|state| state.pid) {
+                    // In some cases docker will report pid 0 as the pid for the
+                    // polled container. This is not usable by us and we believe
+                    // a race condition.
+                    if pid == 0 {
+                        info!(
+                            "Found container with name {name} but with pid {pid}. Polling.",
+                            name = config.name
+                        );
+                        time::sleep(Duration::from_secs(1)).await;
+                        continue;
+                    }
                     break pid;
                 }
             } else {