Add --substituter option

This allows nix-index to e.g. work offline with custom substituter.

Fixes #125.

Author: bjornfor

src/bin/nix-channel-index.rs

@@ -10,12 +10,12 @@ use futures::{future, StreamExt};
 use nix_index::files::{FileNode, FileType};
 use nix_index::hydra::Fetcher;
 use nix_index::listings;
-use nix_index::{errors::*, CACHE_URL};
+use nix_index::{errors::*};
 use rusqlite::Connection;
 
 /// The main function of this module: creates a new command-not-found database.
 async fn update_index(args: &Args) -> Result<()> {
-    let fetcher = Fetcher::new(CACHE_URL.to_string()).map_err(Error::ParseProxy)?;
+    let fetcher = Fetcher::new(args.substituter.to_string()).map_err(Error::ParseProxy)?;
     let connection = Connection::open_in_memory().map_err(|e| Error::CreateDatabase {
         path: args.output.clone(),
         source: Box::new(e),
@@ -197,6 +197,10 @@ struct Args {
     #[clap(short = 's', long = "platform")]
     systems: Option<Vec<String>>,
 
+    /// The substituter (binary cache) URL to query
+    #[clap(long, default_value = "https://cache.nixos.org")]
+    substituter: String,
+
     /// Show a stack trace in the case of a Nix evaluation error
     #[clap(long)]
     show_trace: bool,

src/bin/nix-index.rs

@@ -14,7 +14,6 @@ use nix_index::files::FileTree;
 use nix_index::hydra::Fetcher;
 use nix_index::listings::{self, try_load_paths_cache};
 use nix_index::package::StorePath;
-use nix_index::CACHE_URL;
 use separator::Separatable;
 
 /// The main function of this module: creates a new nix-index database.
@@ -30,7 +29,7 @@ async fn update_index(args: &Args) -> Result<()> {
     };
 
     eprintln!("+ querying available packages");
-    let fetcher = Fetcher::new(CACHE_URL.to_string()).map_err(Error::ParseProxy)?;
+    let fetcher = Fetcher::new(args.substituter.to_string()).map_err(Error::ParseProxy)?;
     let (files, watch) = match cached {
         Some((f, w)) => (Either::Left(f), w),
         None => {
@@ -150,6 +149,10 @@ struct Args {
     #[clap(short = 's', long, value_name = "platform")]
     system: Option<String>,
 
+    /// The substituter (binary cache) URL to query
+    #[clap(long, default_value = "https://cache.nixos.org")]
+    substituter: String,
+
     /// Zstandard compression level
     #[clap(short, long = "compression", default_value = "22")]
     compression_level: i32,

src/lib.rs

@@ -16,8 +16,3 @@ pub mod nixpkgs;
 pub mod package;
 pub mod util;
 pub mod workset;
-
-/// The URL of the binary cache that we use to fetch file listings and references.
-///
-/// Hardcoded for now, but may be made a configurable option in the future.
-pub const CACHE_URL: &str = "https://cache.nixos.org";