Add shell completion (#515)

Cargo.lock

@@ -126,6 +126,15 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "clap_generate"
+version = "3.0.0-beta.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "097ab5db1c3417442270cd57c8dd39f6c3114d3ce09d595f9efddbb1fcfaa799"
+dependencies = [
+ "clap",
+]
+
 [[package]]
 name = "combine"
 version = "2.5.2"
@@ -1333,6 +1342,7 @@ dependencies = [
  "anyhow",
  "chrono",
  "clap",
+ "clap_generate",
  "libcgroups",
  "libcontainer",
  "liboci-cli",

crates/youki/Cargo.toml

@@ -26,6 +26,7 @@ procfs = "0.11.1"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 tabwriter = "1"
+clap_generate = { version = "3.0.0-beta.5" }
 
 [dev-dependencies]
 serial_test = "0.5.1"

crates/youki/src/commands/completion.rs

@@ -0,0 +1,22 @@
+use anyhow::Result;
+use clap::{App, Parser};
+use clap_generate::{generate, Shell};
+use std::io;
+
+#[derive(Debug, Parser)]
+/// Generate scripts for shell completion
+pub struct Completion {
+    #[clap(long = "shell", short = 's', arg_enum)]
+    pub shell: Shell,
+}
+
+pub fn completion(args: Completion, app: &mut App) -> Result<()> {
+    generate(
+        args.shell,
+        app,
+        app.get_name().to_string(),
+        &mut io::stdout(),
+    );
+
+    Ok(())
+}

crates/youki/src/commands/mod.rs

@@ -3,6 +3,7 @@ use std::{fs, path::Path};
 
 use libcontainer::container::Container;
 
+pub mod completion;
 pub mod create;
 pub mod delete;
 pub mod events;

crates/youki/src/main.rs

@@ -4,13 +4,13 @@
 mod commands;
 mod logger;
 
-use std::fs;
-use std::path::{Path, PathBuf};
-
 use anyhow::bail;
 use anyhow::Context;
 use anyhow::Result;
+use clap::IntoApp;
 use clap::{crate_version, Parser};
+use std::fs;
+use std::path::{Path, PathBuf};
 
 use crate::commands::info;
 use libcontainer::rootless::rootless_required;
@@ -46,6 +46,7 @@ enum SubCommand {
 
     // Youki specific extensions
     Info(info::Info),
+    Completion(commands::completion::Completion),
 }
 
 /// This is the entry point in the container runtime. The binary is run by a high-level container runtime,
@@ -64,6 +65,7 @@ fn main() -> Result<()> {
     pentacle::ensure_sealed().context("failed to seal /proc/self/exe")?;
 
     let opts = Opts::parse();
+    let mut app = Opts::into_app();
 
     if let Err(e) = crate::logger::init(opts.global.debug, opts.global.log, opts.global.log_format)
     {
@@ -100,6 +102,9 @@ fn main() -> Result<()> {
         },
 
         SubCommand::Info(info) => commands::info::info(info),
+        SubCommand::Completion(completion) => {
+            commands::completion::completion(completion, &mut app)
+        }
     }
 }