colmena/src/nix/flake.rs
2022-08-16 20:16:00 -06:00

107 lines
2.7 KiB
Rust

//! Nix Flake utilities.
use std::convert::AsRef;
use std::path::{Path, PathBuf};
use std::process::Stdio;
use serde::Deserialize;
use tokio::process::Command;
use super::{ColmenaError, ColmenaResult, NixCheck};
/// A Nix Flake.
#[derive(Debug)]
pub struct Flake {
/// The flake metadata.
metadata: FlakeMetadata,
/// The directory the flake lives in, if it's a local flake.
local_dir: Option<PathBuf>,
}
/// A `nix flake metadata --json` invocation.
#[derive(Deserialize, Debug)]
struct FlakeMetadata {
/// The resolved URL of the flake.
#[serde(rename = "resolvedUrl")]
resolved_url: String,
/// The locked URL of the flake.
url: String,
}
impl Flake {
/// Creates a flake from the given directory.
///
/// This will try to retrieve the resolved URL of the local flake
/// in the specified directory.
pub async fn from_dir<P: AsRef<Path>>(dir: P) -> ColmenaResult<Self> {
NixCheck::require_flake_support().await?;
let flake = dir
.as_ref()
.as_os_str()
.to_str()
.expect("Flake directory path contains non-UTF-8 characters");
let metadata = FlakeMetadata::resolve(flake).await?;
Ok(Self {
metadata,
local_dir: Some(dir.as_ref().to_owned()),
})
}
/// Creates a flake from a Flake URI.
pub async fn from_uri(uri: String) -> ColmenaResult<Self> {
NixCheck::require_flake_support().await?;
let metadata = FlakeMetadata::resolve(&uri).await?;
Ok(Self {
metadata,
local_dir: None,
})
}
/// Returns the URI.
pub fn uri(&self) -> &str {
&self.metadata.resolved_url
}
/// Returns the locked URI.
///
/// Note that the URI will not be locked if the git workspace
/// is dirty.
pub fn locked_uri(&self) -> &str {
&self.metadata.url
}
/// Returns the local directory, if it exists.
pub fn local_dir(&self) -> Option<&Path> {
self.local_dir.as_deref()
}
}
impl FlakeMetadata {
/// Resolves a flake.
async fn resolve(flake: &str) -> ColmenaResult<Self> {
let child = Command::new("nix")
.args(&["flake", "metadata", "--json"])
.args(&["--experimental-features", "nix-command flakes"])
.arg(flake)
.stdout(Stdio::piped())
.spawn()?;
let output = child.wait_with_output().await?;
if !output.status.success() {
return Err(output.status.into());
}
serde_json::from_slice::<FlakeMetadata>(&output.stdout).map_err(|_| {
let output = String::from_utf8_lossy(&output.stdout).to_string();
ColmenaError::BadOutput { output }
})
}
}