setting up a simple CLI with clap

Author: RussellWaite

.gitignore

@@ -13,3 +13,5 @@
 
 # Dependency directories (remove the comment below to include it)
 # vendor/
+target/
+Cargo.lock

agent/Cargo.toml

@@ -3,6 +3,11 @@ name = "agent"
 version = "0.1.0"
 edition = "2021"
 
+[[bin]]
+name = "al"
+path = "src/main.rs"
+
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+clap = { version = "4.1.4", features = ["derive"] }

agent/src/cli.rs

@@ -0,0 +1,36 @@
+use clap::{Parser, Subcommand};
+
+use config::Config;
+use lint::Lint;
+use run::Run;
+
+pub mod config;
+pub mod lint;
+pub mod run;
+
+#[derive(Parser)]
+#[command(name = "al")]
+#[command(version = "0.0")]
+#[command(about = "Assembly Line build agent")]
+#[command(
+    long_about = "Assembly line is a CI/CD system for building and deploying applications focused on using containers as steps on environments that support containers."
+)]
+#[command(author = None)]
+pub struct Cli {
+    #[command(subcommand)]
+    pub command: Commands,
+}
+
+/// Define a finite list of valid sub commands
+#[derive(Subcommand)]
+pub enum Commands {
+    /// Show/set config
+    #[clap(name = "config")]
+    Config(Config),
+    /// Check a pipeline configuration file for correctness
+    Lint(Lint),
+    /// Execute the pipeline specified
+    Run(Run),
+    /// Run as a server, depends on config as to what type - local or true build agent
+    Server,
+}

agent/src/cli/config.rs

@@ -0,0 +1,68 @@
+use clap::{Parser, Subcommand};
+
+/// Defines the options available to the `config` sub command,
+#[derive(Parser)]
+pub struct Config {
+    #[command(subcommand)]
+    command: ConfigCommand,
+}
+
+/// Define a finite list of options that `config`'s `command` can provide
+#[derive(Subcommand)]
+pub enum ConfigCommand {
+    /// Show the current config
+    Get,
+    /// Generate an example config based on a CRI-API supported runtime
+    #[clap(name = "generate")]
+    Generate(Generate),
+}
+
+/// Defines options available to the `config generate` sub command
+#[derive(Parser)]
+pub struct Generate {
+    #[command(subcommand)]
+    command: GenerateConfigCommand,
+}
+
+/// Select a CRI-API enabled endpoint to generate default configuration for
+#[derive(Subcommand)]
+pub enum GenerateConfigCommand {
+    /// Generate config that communicates with a default install of Containerd
+    Containerd,
+    /// Generate config that communicates with a default install of CRI-O
+    CriO,
+    /// Generate config that communicates with a default install od Docker
+    Docker,
+}
+
+/// command handler for the config sub command
+pub fn config_commands(config: Config) {
+    match config.command {
+        ConfigCommand::Get => println!("GET CONFIG CALLED"),
+        ConfigCommand::Generate(flavour) => generate_template_config(flavour),
+    }
+}
+
+/// Calls the generator for the selected CRI-API enabled runtime
+pub fn generate_template_config(flavour: Generate) {
+    match flavour.command {
+        GenerateConfigCommand::Containerd => generate_example_containerd_config(),
+        GenerateConfigCommand::CriO => generate_example_crio_config(),
+        GenerateConfigCommand::Docker => generate_example_docker_config(),
+    }
+}
+
+/// Generate Containerd specific config based on a default install
+pub fn generate_example_containerd_config() {
+    println!("THIS IS WHERE WE OUTPUT CONTAINERD SPECIFIC CONFIG")
+}
+
+/// Generate CRI-O specific config based on a default install
+pub fn generate_example_crio_config() {
+    println!("YOU CHOSE CRI-O")
+}
+
+/// Generate Docker specific config based on a default install
+pub fn generate_example_docker_config() {
+    println!("DOCKER FOR THE WIN")
+}

agent/src/cli/lint.rs

@@ -0,0 +1,14 @@
+use clap::Args;
+use std::path::PathBuf;
+
+/// Arguments for the lint command to control behaviour
+#[derive(Args)]
+pub struct Lint {
+    /// The path of the pipeline file to check for correctness
+    pub path: PathBuf,
+}
+
+/// Lint the pipeline specified by the arguments for correctness
+pub fn lint_command(args: Lint) {
+    println!("YOU CHOSE TO LINT: {:?} (not yet implemented)", args.path)
+}

agent/src/cli/run.rs

@@ -0,0 +1,14 @@
+use clap::Args;
+use std::path::PathBuf;
+
+/// Arguments for the run command to control execution
+#[derive(Args)]
+pub struct Run {
+    /// The path of the pipeline file to run locally
+    pub path: PathBuf,
+}
+
+/// Run the pipeline as specified by the args on the local machine
+pub fn run_command(args: Run) {
+    println!("YOU CHOSE TO RUN: {:?} (not yet implemened)", args.path)
+}

agent/src/main.rs

@@ -1,3 +1,14 @@
+use clap::Parser;
+
+use cli::*;
+mod cli;
+
 fn main() {
-    println!("Hello, world!");
+    let cli = cli::Cli::parse();
+    match cli.command {
+        Commands::Server => println!("RUN AS A SERVER (not yet implemented)"),
+        Commands::Run(run_args) => run::run_command(run_args),
+        Commands::Lint(lint_args) => lint::lint_command(lint_args),
+        Commands::Config(c) => config::config_commands(c),
+    }
 }