support subtituting multiple outputs

src/action/base/fetch_and_unpack_nix_substituter.rs

@@ -36,7 +36,7 @@ pub struct FetchAndUnpackNixSubstituter {
     substituters: Vec<Url>,
     /// Desired derivation output, e.g.
     /// `/nix/store/n50jk09x9hshwx1lh6k3qaiygc7yxbv9-lix-2.90.0-rc1`
-    target: StorePath,
+    targets: Vec<StorePath>,
     /// Destination directory, normally temporary.
     /// For compatibility with tarballs, files will be placed in
     /// the nix-/store subdirectory of the destination
@@ -55,7 +55,7 @@ const STORE_DIR: &str = "/nix/store/";
 impl FetchAndUnpackNixSubstituter {
     #[tracing::instrument(level = "debug", skip_all)]
     pub async fn plan(
-        target: PathBuf,
+        targets: Vec<PathBuf>,
         dest: PathBuf,
         trusted_keys: Vec<String>,
         substituters: Vec<Url>,
@@ -79,9 +79,14 @@ impl FetchAndUnpackNixSubstituter {
             parse_ssl_cert(ssl_cert_file).await.map_err(Self::error)?;
         }
 
+        let targets = targets
+            .iter()
+            .map(|p| StorePath::from_path(p))
+            .collect::<Result<Vec<_>, _>>()
+            .map_err(Self::error)?;
+
         Ok(Self {
-            target: StorePath::from_path(&target)
+            targets,
-                .ok_or_else(|| Self::error(SubstitutionError::InvalidStorePath))?,
             trusted_keys: trusted_keys_parsed,
             dest,
             proxy,
@@ -145,8 +150,12 @@ impl Action for FetchAndUnpackNixSubstituter {
     }
     fn tracing_synopsis(&self) -> String {
         format!(
-            "Fetch `{}` from substituters to `{}`",
+            "Fetch {} from substituters to `{}`",
-            self.target.full_path,
+            self.targets
+                .iter()
+                .map(|t| format!("`{}`", t.full_path))
+                .collect::<Vec<String>>()
+                .join(", "),
             self.dest.display()
         )
     }
@@ -155,7 +164,7 @@ impl Action for FetchAndUnpackNixSubstituter {
         let span = span!(
             tracing::Level::DEBUG,
             "fetch_and_unpack_nix_substituter",
-            target = tracing::field::debug(&self.target.full_path),
+            targets = tracing::field::debug(&self.targets),
             proxy = tracing::field::Empty,
             ssl_cert_file = tracing::field::Empty,
             dest = tracing::field::display(self.dest.display()),
@@ -201,7 +210,7 @@ impl Action for FetchAndUnpackNixSubstituter {
             .map_err(|e| ActionErrorKind::CreateDirectory(nix_store_dir.clone(), e))
             .map_err(Self::error)?;
 
-        let mut outputs_remaining = vec![self.target.clone()];
+        let mut outputs_remaining = self.targets.clone();
         let mut outputs_done = HashSet::new();
         let mut reginfo = String::new();
 
@@ -395,8 +404,12 @@ impl StorePath {
         })
     }
 
-    pub fn from_path(path: &Path) -> Option<Self> {
+    pub fn from_path(path: &Path) -> Result<Self, SubstitutionError> {
-        Self::from_full_path(path.to_str()?)
+        let path_str = path
+            .to_str()
+            .ok_or_else(|| SubstitutionError::InvalidStorePath(path.to_owned()))?;
+        Self::from_full_path(path_str)
+            .ok_or_else(|| SubstitutionError::InvalidStorePath(path.to_owned()))
     }
 
     pub fn from_full_name(full_name: &str) -> Option<Self> {
@@ -684,8 +697,8 @@ pub enum SubstitutionError {
     BadNar(Url),
     #[error("No substituter has path {0}")]
     NonexistantNarInfo(String),
-    #[error("Invalid nix store path")]
+    #[error("Invalid nix store path {0}")]
-    InvalidStorePath,
+    InvalidStorePath(PathBuf),
 }
 
 impl From<SubstitutionError> for ActionErrorKind {

src/action/common/provision_nix.rs

@@ -59,7 +59,7 @@ impl ProvisionNix {
         let fetch_nix = if settings.use_substituters {
             FetchNix::FromSubstituter(
                 FetchAndUnpackNixSubstituter::plan(
-                    settings.substitution_target.clone(),
+                    settings.substitution_targets.clone(),
                     PathBuf::from(SCRATCH_DIR),
                     settings.substituter_trusted_keys.clone(),
                     settings.substituters.clone(),

src/settings.rs

@@ -173,11 +173,14 @@ pub struct CommonSettings {
         feature = "cli",
         clap(
             long,
-            env = "NIX_INSTALLER_SUBSTITUTION_TARGET",
+            env = "NIX_INSTALLER_SUBSTITUTION_TARGETS",
-            default_value = "/nix/store/rp7y16q2py2n9y19jvxkjr83lp77bh7y-lix-2.90.0"
+            default_values = [
+                "/nix/store/rp7y16q2py2n9y19jvxkjr83lp77bh7y-lix-2.90.0",
+                "/nix/store/26n4d7n6bm3d1kvai6zmvzx929z9q5c9-nss-cacert-3.98",
+            ]
         )
     )]
-    pub substitution_target: PathBuf,
+    pub substitution_targets: Vec<PathBuf>,
 
     /// Download Lix from a substituter instead of an install tarball
     #[cfg_attr(feature = "cli", clap(long, env = "NIX_INSTALLER_USE_SUBSTITUTER"))]
@@ -334,7 +337,10 @@ impl CommonSettings {
                 .iter()
                 .map(|s| s.to_string())
                 .collect(),
-            substitution_target: "/nix/store/rp7y16q2py2n9y19jvxkjr83lp77bh7y-lix-2.90.0".into(),
+            substitution_targets: vec![
+                "/nix/store/rp7y16q2py2n9y19jvxkjr83lp77bh7y-lix-2.90.0".into(),
+                "/nix/store/26n4d7n6bm3d1kvai6zmvzx929z9q5c9-nss-cacert-3.98".into(),
+            ],
             use_substituters: false,
             nix_package_url: url.parse()?,
             proxy: Default::default(),
@@ -356,7 +362,7 @@ impl CommonSettings {
             nix_build_user_count,
             substituters,
             substituter_trusted_keys,
-            substitution_target,
+            substitution_targets,
             use_substituters,
             nix_package_url,
             proxy,
@@ -397,8 +403,8 @@ impl CommonSettings {
             serde_json::to_value(substituter_trusted_keys)?,
         );
         map.insert(
-            "substitution_target".into(),
+            "substitution_targets".into(),
-            serde_json::to_value(substitution_target)?,
+            serde_json::to_value(substitution_targets)?,
         );
         map.insert(
             "use_substituters".into(),

tests/fixtures/linux/linux.json

@@ -419,7 +419,9 @@
         "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=",
         "cache.lix.systems:aBnZUw8zA7H35Cz2RyKFVs3H4PlGTLawyY5KRbvJR8o="
       ],
-      "substitution_target": "/nix/store/rp7y16q2py2n9y19jvxkjr83lp77bh7y-lix-2.90.0",
+      "substitution_targets": [
+        "/nix/store/rp7y16q2py2n9y19jvxkjr83lp77bh7y-lix-2.90.0"
+      ],
       "use_substituters": false,
       "nix_package_url": {
         "Url": "https://releases.nixos.org/nix/nix-2.17.0/nix-2.17.0-x86_64-linux.tar.xz"

tests/fixtures/linux/steam-deck.json

@@ -403,7 +403,9 @@
         "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=",
         "cache.lix.systems:aBnZUw8zA7H35Cz2RyKFVs3H4PlGTLawyY5KRbvJR8o="
       ],
-      "substitution_target": "/nix/store/rp7y16q2py2n9y19jvxkjr83lp77bh7y-lix-2.90.0",
+      "substitution_targets": [
+        "/nix/store/rp7y16q2py2n9y19jvxkjr83lp77bh7y-lix-2.90.0"
+      ],
       "use_substituters": false,
       "nix_package_url": {
         "Url": "https://releases.nixos.org/nix/nix-2.17.0/nix-2.17.0-x86_64-linux.tar.xz"

tests/fixtures/macos/macos.json

@@ -430,7 +430,9 @@
         "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=",
         "cache.lix.systems:aBnZUw8zA7H35Cz2RyKFVs3H4PlGTLawyY5KRbvJR8o="
       ],
-      "substitution_target": "/nix/store/rp7y16q2py2n9y19jvxkjr83lp77bh7y-lix-2.90.0",
+      "substitution_target": [
+        "/nix/store/rp7y16q2py2n9y19jvxkjr83lp77bh7y-lix-2.90.0"
+      ],
       "use_substituters": false,
       "nix_package_url": {
         "Url": "https://releases.nixos.org/nix/nix-2.17.0/nix-2.17.0-x86_64-darwin.tar.xz"