Print current kubernetes context or '?'

main.rs

use anyhow::{Error, Result};
use std::env;
use std::fs::read_to_string;
use std::io::{stderr, stdout, Write};
use yaml_rust::YamlLoader;

fn kube_config_path() -> String {
    let mut home = dirs::home_dir().expect("No home directory found");
    home.extend(vec![".kube", "config"]);
    env::var("KUBECONFIG").unwrap_or(
        home.into_os_string()
            .into_string()
            .expect("Could not convert home path"),
    )
}

fn current_context(cfgpath: &str) -> Result<String> {
    let string = read_to_string(cfgpath)?;
    let yaml = YamlLoader::load_from_str(&string)?;
    if yaml.len() == 0 {
        return Err(Error::msg(format!("No YAML in {}", cfgpath)));
    }
    let context = yaml[0]["current-context"].as_str();
    context
        .map(|str| String::from(str))
        .ok_or(Error::msg(format!(
            "No current context found in config file {}",
            cfgpath
        )))
}

fn main() {
    let config_path = kube_config_path();
    match current_context(&config_path) {
        Ok(ctx) => {
            let _ = stdout().write_all(ctx.as_bytes());
            std::process::exit(0);
        }
        Err(e) => {
            let _ = stderr().write_all(e.to_string().as_bytes());
            let _ = stdout().write_all("?".as_bytes());
            std::process::exit(0);
        }
    };
}