Expose target container targetting

When I implemented this in #906 I was working in a stack and completely lost
track of exposing this new work in the CLI: there was no way to flip this
feature on. Fixed in this PR.

Signed-off-by: Brian L. Troutwine <[email protected]>

Author: blt

CHANGELOG.md

@@ -6,6 +6,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+## [0.22.0-rc1]
+### Fixed
+- Target observer was not exposed through CLI.
+
 ## [0.22.0-rc0]
 ### Added
 - Target observer now allows a docker target, identified by name.

Cargo.lock

@@ -1,6 +1,6 @@
 [package]
 name = "lading"
-version = "0.22.0-rc0"
+version = "0.22.0-rc1"
 authors = [
     "Brian L. Troutwine <[email protected]>",
     "George Hahn <[email protected]>",

lading/Cargo.toml

@@ -131,7 +131,7 @@ impl FromStr for CliKeyValues {
 #[clap(group(
     ArgGroup::new("target")
         .required(true)
-        .args(&["target-path", "target-pid", "no-target"]),
+        .args(&["target-path", "target-pid", "target-container", "no-target"]),
 ))]
 #[clap(group(
     ArgGroup::new("telemetry")
@@ -153,6 +153,9 @@ struct Opts {
     /// measure an externally-launched process by PID
     #[clap(long)]
     target_pid: Option<NonZeroU32>,
+    /// measure an externally-launched container by name
+    #[clap(long)]
+    target_container: Option<String>,
     /// disable target measurement
     #[clap(long)]
     no_target: bool,
@@ -264,6 +267,10 @@ fn get_config(ops: &Opts, config: Option<String>) -> Result<Config, Error> {
         None
     } else if let Some(pid) = ops.target_pid {
         Some(target::Config::Pid(target::PidConfig { pid }))
+    } else if let Some(name) = &ops.target_container {
+        Some(target::Config::Docker(target::DockerConfig {
+            name: name.clone(),
+        }))
     } else if let Some(path) = &ops.target_path {
         Some(target::Config::Binary(target::BinaryConfig {
             command: path.clone(),