colmena/src/command/eval.rs
2022-03-07 22:02:04 -08:00

73 lines
2.5 KiB
Rust

use std::path::PathBuf;
use clap::{Arg, Command as ClapCommand, ArgMatches};
use crate::error::ColmenaError;
use crate::util;
pub fn subcommand() -> ClapCommand<'static> {
subcommand_gen("eval")
}
pub fn deprecated_alias() -> ClapCommand<'static> {
subcommand_gen("introspect")
.hide(true)
}
fn subcommand_gen(name: &str) -> ClapCommand<'static> {
ClapCommand::new(name)
.about("Evaluate an expression using the complete configuration")
.long_about(r#"Evaluate an expression using the complete configuration
Your expression should take an attribute set with keys `pkgs`, `lib` and `nodes` (like a NixOS module) and return a JSON-serializable value.
For example, to retrieve the configuration of one node, you may write something like:
{ nodes, ... }: nodes.node-a.config.networking.hostName
"#)
.arg(Arg::new("expression_file")
.index(1)
.value_name("FILE")
.help("The .nix file containing the expression")
.takes_value(true))
.arg(Arg::new("expression")
.short('E')
.value_name("EXPRESSION")
.help("The Nix expression")
.takes_value(true))
.arg(Arg::new("instantiate")
.long("instantiate")
.help("Actually instantiate the expression")
.takes_value(false))
}
pub async fn run(global_args: &ArgMatches, local_args: &ArgMatches) -> Result<(), ColmenaError> {
if let Some("introspect") = global_args.subcommand_name() {
log::warn!("`colmena introspect` has been renamed to `colmena eval`. Please update your scripts.");
}
let hive = util::hive_from_args(local_args).await?;
if !(local_args.is_present("expression") ^ local_args.is_present("expression_file")) {
log::error!("Either an expression (-E) or a .nix file containing an expression should be specified, not both.");
quit::with_code(1);
}
let expression = if local_args.is_present("expression") {
local_args.value_of("expression").unwrap().to_string()
} else {
let path: PathBuf = local_args.value_of("expression_file").unwrap().into();
format!("import {}", path.canonicalize().expect("Could not generate absolute path to expression file.").to_str().unwrap())
};
let instantiate = local_args.is_present("instantiate");
let result = hive.introspect(expression, instantiate).await?;
if instantiate {
print!("{}", result);
} else {
println!("{}", result);
}
Ok(())
}