feat(tvix/store/pathinfoservice): implement NixHTTPPathInfoService r/7038

NixHTTPPathInfoService acts as a bridge in between the Nix HTTP Binary
cache protocol provided by Nix binary caches such as cache.nixos.org,
and the Tvix Store Model.
It implements the [PathInfoService] trait in an interesting way: Every
[PathInfoService::get] fetches the .narinfo and referred NAR file,
inserting components into a [BlobService] and [DirectoryService], then
returning a [PathInfo] struct with the root.
Due to this being quite a costly operation, clients are expected to
layer this service with store composition, so they're only ingested
once.
The client is expected to be (indirectly) using the same [BlobService]
and [DirectoryService], so able to fetch referred Directories and Blobs.
[PathInfoService::put] and [PathInfoService::nar] are not implemented
and return an error if called.

This behaves very similar to the nar-bridge-pathinfo code in nar-bridge,
except it's now in Rust.

Change-Id: Ia03d4fed9d0657965d100299af97cd917a03f2f0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10069
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: raitobezarius <tvl@lahfa.xyz>

6 files changed, 1043 insertions, 10 deletions

diff --git a/tvix/Cargo.lock b/tvix/Cargo.lock
index 72da9607466f..2b05ed744e39 100644
--- a/tvix/Cargo.lock
+++ b/tvix/Cargo.lock
@@ -694,6 +694,15 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7fcaabb2fef8c910e7f4c7ce9f67a1283a1715879a7c230ca9d6d1ae31f16d91"
 
 [[package]]
+name = "encoding_rs"
+version = "0.8.33"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7268b386296a025e474d5140678f75d6de9493ae55a5d709eeb9dd08149945e1"
+dependencies = [
+ "cfg-if",
+]
+
+[[package]]
 name = "endian-type"
 version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1065,6 +1074,20 @@ dependencies = [
 ]
 
 [[package]]
+name = "hyper-rustls"
+version = "0.24.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec3efd23720e2049821a693cbc7e65ea87c72f1c58ff2f9522ff332b1491e590"
+dependencies = [
+ "futures-util",
+ "http",
+ "hyper",
+ "rustls",
+ "tokio",
+ "tokio-rustls",
+]
+
+[[package]]
 name = "hyper-timeout"
 version = "0.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1141,6 +1164,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "ipnet"
+version = "2.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f518f335dce6725a761382244631d86cf0ccb2863413590b31338feb467f9c3"
+
+[[package]]
 name = "is-terminal"
 version = "0.4.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1299,6 +1328,17 @@ dependencies = [
 ]
 
 [[package]]
+name = "lzma-sys"
+version = "0.1.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5fda04ab3764e6cde78b9974eec4f779acaba7c4e84b36eca3cf77c581b85d27"
+dependencies = [
+ "cc",
+ "libc",
+ "pkg-config",
+]
+
+[[package]]
 name = "matchit"
 version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1634,6 +1674,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8b870d8c151b6f2fb93e84a13146138f05d02ed11c7e7c54f8826aaaf7c9f184"
 
 [[package]]
+name = "pkg-config"
+version = "0.3.27"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "26072860ba924cbfa98ea39c8c19b4dd6a4a25423dbdf219c1eca91aa0cf6964"
+
+[[package]]
 name = "plotters"
 version = "0.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1960,6 +2006,48 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a5996294f19bd3aae0453a862ad728f60e6600695733dd5df01da90c54363a3c"
 
 [[package]]
+name = "reqwest"
+version = "0.11.22"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "046cd98826c46c2ac8ddecae268eb5c2e58628688a5fc7a2643704a73faba95b"
+dependencies = [
+ "base64",
+ "bytes",
+ "encoding_rs",
+ "futures-core",
+ "futures-util",
+ "h2",
+ "http",
+ "http-body",
+ "hyper",
+ "hyper-rustls",
+ "ipnet",
+ "js-sys",
+ "log",
+ "mime",
+ "once_cell",
+ "percent-encoding",
+ "pin-project-lite",
+ "rustls",
+ "rustls-pemfile",
+ "serde",
+ "serde_json",
+ "serde_urlencoded",
+ "system-configuration",
+ "tokio",
+ "tokio-rustls",
+ "tokio-util",
+ "tower-service",
+ "url",
+ "wasm-bindgen",
+ "wasm-bindgen-futures",
+ "wasm-streams",
+ "web-sys",
+ "webpki-roots",
+ "winreg",
+]
+
+[[package]]
 name = "ring"
 version = "0.16.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -2210,6 +2298,18 @@ dependencies = [
 ]
 
 [[package]]
+name = "serde_urlencoded"
+version = "0.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d3491c14715ca2294c4d6a88f15e84739788c1d030eed8c110436aafdaa2f3fd"
+dependencies = [
+ "form_urlencoded",
+ "itoa",
+ "ryu",
+ "serde",
+]
+
+[[package]]
 name = "sha2"
 version = "0.10.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -2392,6 +2492,27 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2047c6ded9c721764247e62cd3b03c09ffc529b2ba5b10ec482ae507a4a70160"
 
 [[package]]
+name = "system-configuration"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ba3a3adc5c275d719af8cb4272ea1c4a6d668a777f37e115f6d11ddbc1c8e0e7"
+dependencies = [
+ "bitflags 1.3.2",
+ "core-foundation",
+ "system-configuration-sys",
+]
+
+[[package]]
+name = "system-configuration-sys"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a75fb188eb626b924683e3b95e3a48e63551fcfb51949de2f06a9d91dbee93c9"
+dependencies = [
+ "core-foundation-sys",
+ "libc",
+]
+
+[[package]]
 name = "tabwriter"
 version = "1.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -2977,6 +3098,7 @@ dependencies = [
  "pin-project-lite",
  "prost",
  "prost-build",
+ "reqwest",
  "sha2",
  "sled",
  "tempfile",
@@ -3002,6 +3124,7 @@ dependencies = [
  "vm-memory",
  "vmm-sys-util",
  "walkdir",
+ "xz2",
 ]
 
 [[package]]
@@ -3223,6 +3346,18 @@ dependencies = [
 ]
 
 [[package]]
+name = "wasm-bindgen-futures"
+version = "0.4.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f219e0d211ba40266969f6dbdd90636da12f75bee4fc9d6c23d1260dadb51454"
+dependencies = [
+ "cfg-if",
+ "js-sys",
+ "wasm-bindgen",
+ "web-sys",
+]
+
+[[package]]
 name = "wasm-bindgen-macro"
 version = "0.2.84"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -3252,6 +3387,19 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0046fef7e28c3804e5e38bfa31ea2a0f73905319b677e57ebe37e49358989b5d"
 
 [[package]]
+name = "wasm-streams"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b4609d447824375f43e1ffbc051b50ad8f4b3ae8219680c94452ea05eb240ac7"
+dependencies = [
+ "futures-util",
+ "js-sys",
+ "wasm-bindgen",
+ "wasm-bindgen-futures",
+ "web-sys",
+]
+
+[[package]]
 name = "web-sys"
 version = "0.3.61"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -3262,6 +3410,12 @@ dependencies = [
 ]
 
 [[package]]
+name = "webpki-roots"
+version = "0.25.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "14247bb57be4f377dfb94c72830b8ce8fc6beac03cf4bf7b9732eadd414123fc"
+
+[[package]]
 name = "which"
 version = "4.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -3436,6 +3590,16 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1a515f5799fe4961cb532f983ce2b23082366b898e52ffbce459c86f67c8378a"
 
 [[package]]
+name = "winreg"
+version = "0.50.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "524e57b2c537c0f9b1e69f1965311ec12182b4122e45035b1508cd24d2adadb1"
+dependencies = [
+ "cfg-if",
+ "windows-sys 0.48.0",
+]
+
+[[package]]
 name = "wu-manber"
 version = "0.1.0"
 source = "git+https://github.com/tvlfyi/wu-manber.git#0d5b22bea136659f7de60b102a7030e0daaa503d"
@@ -3447,6 +3611,15 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bab77e97b50aee93da431f2cee7cd0f43b4d1da3c408042f2d7d164187774f0a"
 
 [[package]]
+name = "xz2"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "388c44dc09d76f1536602ead6d325eb532f5c122f17782bd57fb47baeeb767e2"
+dependencies = [
+ "lzma-sys",
+]
+
+[[package]]
 name = "yansi"
 version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
diff --git a/tvix/Cargo.nix b/tvix/Cargo.nix
index 261ff74c99b2..98a0e67a6272 100644
--- a/tvix/Cargo.nix
+++ b/tvix/Cargo.nix
@@ -2015,6 +2015,29 @@ rec {
         };
         resolvedDefaultFeatures = [ "default" "use_std" ];
       };
+      "encoding_rs" = rec {
+        crateName = "encoding_rs";
+        version = "0.8.33";
+        edition = "2018";
+        sha256 = "1qa5k4a0ipdrxq4xg9amms9r9pnnfn7nfh2i9m3mw0ka563b6s3j";
+        authors = [
+          "Henri Sivonen <hsivonen@hsivonen.fi>"
+        ];
+        dependencies = [
+          {
+            name = "cfg-if";
+            packageId = "cfg-if";
+          }
+        ];
+        features = {
+          "default" = [ "alloc" ];
+          "fast-legacy-encode" = [ "fast-hangul-encode" "fast-hanja-encode" "fast-kanji-encode" "fast-gb-hanzi-encode" "fast-big5-hanzi-encode" ];
+          "packed_simd" = [ "dep:packed_simd" ];
+          "serde" = [ "dep:serde" ];
+          "simd-accel" = [ "packed_simd" "packed_simd/into_bits" ];
+        };
+        resolvedDefaultFeatures = [ "alloc" "default" ];
+      };
       "endian-type" = rec {
         crateName = "endian-type";
         version = "0.1.2";
@@ -3171,6 +3194,75 @@ rec {
         };
         resolvedDefaultFeatures = [ "client" "default" "full" "h2" "http1" "http2" "runtime" "server" "socket2" "stream" "tcp" ];
       };
+      "hyper-rustls" = rec {
+        crateName = "hyper-rustls";
+        version = "0.24.2";
+        edition = "2021";
+        sha256 = "1475j4a2nczz4aajzzsq3hpwg1zacmzbqg393a14j80ff8izsgpc";
+        dependencies = [
+          {
+            name = "futures-util";
+            packageId = "futures-util";
+            usesDefaultFeatures = false;
+          }
+          {
+            name = "http";
+            packageId = "http";
+          }
+          {
+            name = "hyper";
+            packageId = "hyper";
+            usesDefaultFeatures = false;
+            features = [ "client" ];
+          }
+          {
+            name = "rustls";
+            packageId = "rustls";
+            usesDefaultFeatures = false;
+          }
+          {
+            name = "tokio";
+            packageId = "tokio";
+          }
+          {
+            name = "tokio-rustls";
+            packageId = "tokio-rustls";
+            usesDefaultFeatures = false;
+          }
+        ];
+        devDependencies = [
+          {
+            name = "hyper";
+            packageId = "hyper";
+            features = [ "full" ];
+          }
+          {
+            name = "rustls";
+            packageId = "rustls";
+            usesDefaultFeatures = false;
+            features = [ "tls12" ];
+          }
+          {
+            name = "tokio";
+            packageId = "tokio";
+            features = [ "io-std" "macros" "net" "rt-multi-thread" ];
+          }
+        ];
+        features = {
+          "acceptor" = [ "hyper/server" "tokio-runtime" ];
+          "default" = [ "native-tokio" "http1" "tls12" "logging" "acceptor" ];
+          "http1" = [ "hyper/http1" ];
+          "http2" = [ "hyper/http2" ];
+          "log" = [ "dep:log" ];
+          "logging" = [ "log" "tokio-rustls/logging" "rustls/logging" ];
+          "native-tokio" = [ "tokio-runtime" "rustls-native-certs" ];
+          "rustls-native-certs" = [ "dep:rustls-native-certs" ];
+          "tls12" = [ "tokio-rustls/tls12" "rustls/tls12" ];
+          "tokio-runtime" = [ "hyper/runtime" ];
+          "webpki-roots" = [ "dep:webpki-roots" ];
+          "webpki-tokio" = [ "tokio-runtime" "webpki-roots" ];
+        };
+      };
       "hyper-timeout" = rec {
         crateName = "hyper-timeout";
         version = "0.4.1";
@@ -3422,6 +3514,24 @@ rec {
         };
         resolvedDefaultFeatures = [ "close" "default" "hermit-abi" "libc" "windows-sys" ];
       };
+      "ipnet" = rec {
+        crateName = "ipnet";
+        version = "2.9.0";
+        edition = "2018";
+        sha256 = "1hzrcysgwf0knf83ahb3535hrkw63mil88iqc6kjaryfblrqylcg";
+        authors = [
+          "Kris Price <kris@krisprice.nz>"
+        ];
+        features = {
+          "default" = [ "std" ];
+          "heapless" = [ "dep:heapless" ];
+          "json" = [ "serde" "schemars" ];
+          "schemars" = [ "dep:schemars" ];
+          "ser_as_str" = [ "heapless" ];
+          "serde" = [ "dep:serde" ];
+        };
+        resolvedDefaultFeatures = [ "default" "std" ];
+      };
       "is-terminal" = rec {
         crateName = "is-terminal";
         version = "0.4.7";
@@ -3875,6 +3985,32 @@ rec {
         };
         resolvedDefaultFeatures = [ "std" ];
       };
+      "lzma-sys" = rec {
+        crateName = "lzma-sys";
+        version = "0.1.20";
+        edition = "2018";
+        sha256 = "09sxp20waxyglgn3cjz8qjkspb3ryz2fwx4rigkwvrk46ymh9njz";
+        authors = [
+          "Alex Crichton <alex@alexcrichton.com>"
+        ];
+        dependencies = [
+          {
+            name = "libc";
+            packageId = "libc";
+          }
+        ];
+        buildDependencies = [
+          {
+            name = "cc";
+            packageId = "cc";
+          }
+          {
+            name = "pkg-config";
+            packageId = "pkg-config";
+          }
+        ];
+        features = { };
+      };
       "matchit" = rec {
         crateName = "matchit";
         version = "0.7.0";
@@ -4815,6 +4951,16 @@ rec {
         ];
 
       };
+      "pkg-config" = rec {
+        crateName = "pkg-config";
+        version = "0.3.27";
+        edition = "2015";
+        sha256 = "0r39ryh1magcq4cz5g9x88jllsnxnhcqr753islvyk4jp9h2h1r6";
+        authors = [
+          "Alex Crichton <alex@alexcrichton.com>"
+        ];
+
+      };
       "plotters" = rec {
         crateName = "plotters";
         version = "0.3.4";
@@ -5776,6 +5922,275 @@ rec {
         };
         resolvedDefaultFeatures = [ "default" "std" "unicode" "unicode-age" "unicode-bool" "unicode-case" "unicode-gencat" "unicode-perl" "unicode-script" "unicode-segment" ];
       };
+      "reqwest" = rec {
+        crateName = "reqwest";
+        version = "0.11.22";
+        edition = "2018";
+        sha256 = "0nx9mczsf11pcjicfpwad0l8drf2nn72dbpcvp42lv644s4djv04";
+        authors = [
+          "Sean McArthur <sean@seanmonstar.com>"
+        ];
+        dependencies = [
+          {
+            name = "base64";
+            packageId = "base64";
+          }
+          {
+            name = "bytes";
+            packageId = "bytes";
+          }
+          {
+            name = "encoding_rs";
+            packageId = "encoding_rs";
+            target = { target, features }: (!("wasm32" == target."arch"));
+          }
+          {
+            name = "futures-core";
+            packageId = "futures-core";
+            usesDefaultFeatures = false;
+          }
+          {
+            name = "futures-util";
+            packageId = "futures-util";
+            usesDefaultFeatures = false;
+          }
+          {
+            name = "h2";
+            packageId = "h2";
+            target = { target, features }: (!("wasm32" == target."arch"));
+          }
+          {
+            name = "http";
+            packageId = "http";
+          }
+          {
+            name = "http-body";
+            packageId = "http-body";
+            target = { target, features }: (!("wasm32" == target."arch"));
+          }
+          {
+            name = "hyper";
+            packageId = "hyper";
+            usesDefaultFeatures = false;
+            target = { target, features }: (!("wasm32" == target."arch"));
+            features = [ "tcp" "http1" "http2" "client" "runtime" ];
+          }
+          {
+            name = "hyper-rustls";
+            packageId = "hyper-rustls";
+            optional = true;
+            usesDefaultFeatures = false;
+            target = { target, features }: (!("wasm32" == target."arch"));
+          }
+          {
+            name = "ipnet";
+            packageId = "ipnet";
+            target = { target, features }: (!("wasm32" == target."arch"));
+          }
+          {
+            name = "js-sys";
+            packageId = "js-sys";
+            target = { target, features }: ("wasm32" == target."arch");
+          }
+          {
+            name = "log";
+            packageId = "log";
+            target = { target, features }: (!("wasm32" == target."arch"));
+          }
+          {
+            name = "mime";
+            packageId = "mime";
+            target = { target, features }: (!("wasm32" == target."arch"));
+          }
+          {
+            name = "once_cell";
+            packageId = "once_cell";
+            target = { target, features }: (!("wasm32" == target."arch"));
+          }
+          {
+            name = "percent-encoding";
+            packageId = "percent-encoding";
+            target = { target, features }: (!("wasm32" == target."arch"));
+          }
+          {
+            name = "pin-project-lite";
+            packageId = "pin-project-lite";
+            target = { target, features }: (!("wasm32" == target."arch"));
+          }
+          {
+            name = "rustls";
+            packageId = "rustls";
+            optional = true;
+            target = { target, features }: (!("wasm32" == target."arch"));
+            features = [ "dangerous_configuration" ];
+          }
+          {
+            name = "rustls-pemfile";
+            packageId = "rustls-pemfile";
+            optional = true;
+            target = { target, features }: (!("wasm32" == target."arch"));
+          }
+          {
+            name = "serde";
+            packageId = "serde";
+          }
+          {
+            name = "serde_json";
+            packageId = "serde_json";
+            optional = true;
+          }
+          {
+            name = "serde_json";
+            packageId = "serde_json";
+            target = { target, features }: ("wasm32" == target."arch");
+          }
+          {
+            name = "serde_urlencoded";
+            packageId = "serde_urlencoded";
+          }
+          {
+            name = "system-configuration";
+            packageId = "system-configuration";
+            target = { target, features }: ("macos" == target."os");
+          }
+          {
+            name = "tokio";
+            packageId = "tokio";
+            usesDefaultFeatures = false;
+            target = { target, features }: (!("wasm32" == target."arch"));
+            features = [ "net" "time" ];
+          }
+          {
+            name = "tokio-rustls";
+            packageId = "tokio-rustls";
+            optional = true;
+            target = { target, features }: (!("wasm32" == target."arch"));
+          }
+          {
+            name = "tokio-util";
+            packageId = "tokio-util";
+            optional = true;
+            usesDefaultFeatures = false;
+            target = { target, features }: (!("wasm32" == target."arch"));
+            features = [ "codec" "io" ];
+          }
+          {
+            name = "tower-service";
+            packageId = "tower-service";
+          }
+          {
+            name = "url";
+            packageId = "url";
+          }
+          {
+            name = "wasm-bindgen";
+            packageId = "wasm-bindgen";
+            target = { target, features }: ("wasm32" == target."arch");
+          }
+          {
+            name = "wasm-bindgen-futures";
+            packageId = "wasm-bindgen-futures";
+            target = { target, features }: ("wasm32" == target."arch");
+          }
+          {
+            name = "wasm-streams";
+            packageId = "wasm-streams";
+            optional = true;
+            target = { target, features }: ("wasm32" == target."arch");
+          }
+          {
+            name = "web-sys";
+            packageId = "web-sys";
+            target = { target, features }: ("wasm32" == target."arch");
+            features = [ "AbortController" "AbortSignal" "Headers" "Request" "RequestInit" "RequestMode" "Response" "Window" "FormData" "Blob" "BlobPropertyBag" "ServiceWorkerGlobalScope" "RequestCredentials" "File" "ReadableStream" ];
+          }
+          {
+            name = "webpki-roots";
+            packageId = "webpki-roots";
+            optional = true;
+            target = { target, features }: (!("wasm32" == target."arch"));
+          }
+          {
+            name = "winreg";
+            packageId = "winreg";
+            target = { target, features }: (target."windows" or false);
+          }
+        ];
+        devDependencies = [
+          {
+            name = "hyper";
+            packageId = "hyper";
+            usesDefaultFeatures = false;
+            target = { target, features }: (!("wasm32" == target."arch"));
+            features = [ "tcp" "stream" "http1" "http2" "client" "server" "runtime" ];
+          }
+          {
+            name = "serde";
+            packageId = "serde";
+            target = { target, features }: (!("wasm32" == target."arch"));
+            features = [ "derive" ];
+          }
+          {
+            name = "tokio";
+            packageId = "tokio";
+            usesDefaultFeatures = false;
+            target = { target, features }: (!("wasm32" == target."arch"));
+            features = [ "macros" "rt-multi-thread" ];
+          }
+          {
+            name = "wasm-bindgen";
+            packageId = "wasm-bindgen";
+            target = { target, features }: ("wasm32" == target."arch");
+            features = [ "serde-serialize" ];
+          }
+        ];
+        features = {
+          "__rustls" = [ "hyper-rustls" "tokio-rustls" "rustls" "__tls" "rustls-pemfile" ];
+          "async-compression" = [ "dep:async-compression" ];
+          "blocking" = [ "futures-util/io" "tokio/rt-multi-thread" "tokio/sync" ];
+          "brotli" = [ "async-compression" "async-compression/brotli" "tokio-util" ];
+          "cookie_crate" = [ "dep:cookie_crate" ];
+          "cookie_store" = [ "dep:cookie_store" ];
+          "cookies" = [ "cookie_crate" "cookie_store" ];
+          "default" = [ "default-tls" ];
+          "default-tls" = [ "hyper-tls" "native-tls-crate" "__tls" "tokio-native-tls" ];
+          "deflate" = [ "async-compression" "async-compression/zlib" "tokio-util" ];
+          "futures-channel" = [ "dep:futures-channel" ];
+          "gzip" = [ "async-compression" "async-compression/gzip" "tokio-util" ];
+          "h3" = [ "dep:h3" ];
+          "h3-quinn" = [ "dep:h3-quinn" ];
+          "http3" = [ "rustls-tls-manual-roots" "h3" "h3-quinn" "quinn" "futures-channel" ];
+          "hyper-rustls" = [ "dep:hyper-rustls" ];
+          "hyper-tls" = [ "dep:hyper-tls" ];
+          "json" = [ "serde_json" ];
+          "mime_guess" = [ "dep:mime_guess" ];
+          "multipart" = [ "mime_guess" ];
+          "native-tls" = [ "default-tls" ];
+          "native-tls-alpn" = [ "native-tls" "native-tls-crate/alpn" ];
+          "native-tls-crate" = [ "dep:native-tls-crate" ];
+          "native-tls-vendored" = [ "native-tls" "native-tls-crate/vendored" ];
+          "quinn" = [ "dep:quinn" ];
+          "rustls" = [ "dep:rustls" ];
+          "rustls-native-certs" = [ "dep:rustls-native-certs" ];
+          "rustls-pemfile" = [ "dep:rustls-pemfile" ];
+          "rustls-tls" = [ "rustls-tls-webpki-roots" ];
+          "rustls-tls-manual-roots" = [ "__rustls" ];
+          "rustls-tls-native-roots" = [ "rustls-native-certs" "__rustls" ];
+          "rustls-tls-webpki-roots" = [ "webpki-roots" "__rustls" ];
+          "serde_json" = [ "dep:serde_json" ];
+          "socks" = [ "tokio-socks" ];
+          "stream" = [ "tokio/fs" "tokio-util" "wasm-streams" ];
+          "tokio-native-tls" = [ "dep:tokio-native-tls" ];
+          "tokio-rustls" = [ "dep:tokio-rustls" ];
+          "tokio-socks" = [ "dep:tokio-socks" ];
+          "tokio-util" = [ "dep:tokio-util" ];
+          "trust-dns" = [ "trust-dns-resolver" ];
+          "trust-dns-resolver" = [ "dep:trust-dns-resolver" ];
+          "wasm-streams" = [ "dep:wasm-streams" ];
+          "webpki-roots" = [ "dep:webpki-roots" ];
+        };
+        resolvedDefaultFeatures = [ "__rustls" "__tls" "hyper-rustls" "rustls" "rustls-pemfile" "rustls-tls" "rustls-tls-webpki-roots" "stream" "tokio-rustls" "tokio-util" "wasm-streams" "webpki-roots" ];
+      };
       "ring" = rec {
         crateName = "ring";
         version = "0.16.20";
@@ -6094,7 +6509,7 @@ rec {
           "read_buf" = [ "rustversion" ];
           "rustversion" = [ "dep:rustversion" ];
         };
-        resolvedDefaultFeatures = [ "default" "log" "logging" "tls12" ];
+        resolvedDefaultFeatures = [ "dangerous_configuration" "default" "log" "logging" "tls12" ];
       };
       "rustls-native-certs" = rec {
         crateName = "rustls-native-certs";
@@ -6577,6 +6992,34 @@ rec {
         };
         resolvedDefaultFeatures = [ "serde" ];
       };
+      "serde_urlencoded" = rec {
+        crateName = "serde_urlencoded";
+        version = "0.7.1";
+        edition = "2018";
+        sha256 = "1zgklbdaysj3230xivihs30qi5vkhigg323a9m62k8jwf4a1qjfk";
+        authors = [
+          "Anthony Ramine <n.oxyde@gmail.com>"
+        ];
+        dependencies = [
+          {
+            name = "form_urlencoded";
+            packageId = "form_urlencoded";
+          }
+          {
+            name = "itoa";
+            packageId = "itoa";
+          }
+          {
+            name = "ryu";
+            packageId = "ryu";
+          }
+          {
+            name = "serde";
+            packageId = "serde";
+          }
+        ];
+
+      };
       "sha2" = rec {
         crateName = "sha2";
         version = "0.10.6";
@@ -7072,6 +7515,50 @@ rec {
           "futures-core" = [ "dep:futures-core" ];
         };
       };
+      "system-configuration" = rec {
+        crateName = "system-configuration";
+        version = "0.5.1";
+        edition = "2021";
+        sha256 = "1rz0r30xn7fiyqay2dvzfy56cvaa3km74hnbz2d72p97bkf3lfms";
+        authors = [
+          "Mullvad VPN"
+        ];
+        dependencies = [
+          {
+            name = "bitflags";
+            packageId = "bitflags 1.3.2";
+          }
+          {
+            name = "core-foundation";
+            packageId = "core-foundation";
+          }
+          {
+            name = "system-configuration-sys";
+            packageId = "system-configuration-sys";
+          }
+        ];
+
+      };
+      "system-configuration-sys" = rec {
+        crateName = "system-configuration-sys";
+        version = "0.5.0";
+        edition = "2021";
+        sha256 = "1jckxvdr37bay3i9v52izgy52dg690x5xfg3hd394sv2xf4b2px7";
+        authors = [
+          "Mullvad VPN"
+        ];
+        dependencies = [
+          {
+            name = "core-foundation-sys";
+            packageId = "core-foundation-sys";
+          }
+          {
+            name = "libc";
+            packageId = "libc";
+          }
+        ];
+
+      };
       "tabwriter" = rec {
         crateName = "tabwriter";
         version = "1.2.1";
@@ -9140,6 +9627,12 @@ rec {
             packageId = "prost";
           }
           {
+            name = "reqwest";
+            packageId = "reqwest";
+            usesDefaultFeatures = false;
+            features = [ "rustls-tls" "stream" ];
+          }
+          {
             name = "sha2";
             packageId = "sha2";
           }
@@ -9237,6 +9730,10 @@ rec {
             name = "walkdir";
             packageId = "walkdir";
           }
+          {
+            name = "xz2";
+            packageId = "xz2";
+          }
         ];
         buildDependencies = [
           {
@@ -9812,6 +10309,39 @@ rec {
         };
         resolvedDefaultFeatures = [ "spans" ];
       };
+      "wasm-bindgen-futures" = rec {
+        crateName = "wasm-bindgen-futures";
+        version = "0.4.34";
+        edition = "2018";
+        sha256 = "0m0lnnnhs9ni4dn9vz74prsjz8bdcf8dvnznd5ljch5s279f06gj";
+        authors = [
+          "The wasm-bindgen Developers"
+        ];
+        dependencies = [
+          {
+            name = "cfg-if";
+            packageId = "cfg-if";
+          }
+          {
+            name = "js-sys";
+            packageId = "js-sys";
+          }
+          {
+            name = "wasm-bindgen";
+            packageId = "wasm-bindgen";
+          }
+          {
+            name = "web-sys";
+            packageId = "web-sys";
+            target = { target, features }: (builtins.elem "atomics" targetFeatures);
+            features = [ "MessageEvent" "Worker" ];
+          }
+        ];
+        features = {
+          "futures-core" = [ "dep:futures-core" ];
+          "futures-core-03-stream" = [ "futures-core" ];
+        };
+      };
       "wasm-bindgen-macro" = rec {
         crateName = "wasm-bindgen-macro";
         version = "0.2.84";
@@ -9884,6 +10414,48 @@ rec {
         ];
 
       };
+      "wasm-streams" = rec {
+        crateName = "wasm-streams";
+        version = "0.3.0";
+        edition = "2021";
+        sha256 = "1iqa4kmhbsjj8k4q15i1x0x4p3xda0dhbg7zw51mydr4g129sq5l";
+        type = [ "cdylib" "rlib" ];
+        authors = [
+          "Mattias Buelens <mattias@buelens.com>"
+        ];
+        dependencies = [
+          {
+            name = "futures-util";
+            packageId = "futures-util";
+            features = [ "io" "sink" ];
+          }
+          {
+            name = "js-sys";
+            packageId = "js-sys";
+          }
+          {
+            name = "wasm-bindgen";
+            packageId = "wasm-bindgen";
+          }
+          {
+            name = "wasm-bindgen-futures";
+            packageId = "wasm-bindgen-futures";
+          }
+          {
+            name = "web-sys";
+            packageId = "web-sys";
+            features = [ "AbortSignal" ];
+          }
+        ];
+        devDependencies = [
+          {
+            name = "web-sys";
+            packageId = "web-sys";
+            features = [ "console" "AbortSignal" "Response" "ReadableStream" "Window" ];
+          }
+        ];
+
+      };
       "web-sys" = rec {
         crateName = "web-sys";
         version = "0.3.61";
@@ -10339,7 +10911,14 @@ rec {
           "XrViewerPose" = [ "XrPose" ];
           "XrWebGlLayer" = [ "EventTarget" "XrLayer" ];
         };
-        resolvedDefaultFeatures = [ "CanvasRenderingContext2d" "Crypto" "Document" "DomRect" "DomRectReadOnly" "Element" "EventTarget" "HtmlCanvasElement" "HtmlElement" "Node" "Window" ];
+        resolvedDefaultFeatures = [ "AbortController" "AbortSignal" "Blob" "BlobPropertyBag" "CanvasRenderingContext2d" "Crypto" "Document" "DomRect" "DomRectReadOnly" "Element" "Event" "EventTarget" "File" "FormData" "Headers" "HtmlCanvasElement" "HtmlElement" "MessageEvent" "Node" "ReadableStream" "Request" "RequestCredentials" "RequestInit" "RequestMode" "Response" "ServiceWorkerGlobalScope" "Window" "Worker" "WorkerGlobalScope" ];
+      };
+      "webpki-roots" = rec {
+        crateName = "webpki-roots";
+        version = "0.25.2";
+        edition = "2018";
+        sha256 = "1z13850xvsijjxxvzx1wq3m6pz78ih5q6wjcp7gpgwz4gfspn90l";
+
       };
       "which" = rec {
         crateName = "which";
@@ -11008,7 +11587,7 @@ rec {
           "Win32_Web" = [ "Win32" ];
           "Win32_Web_InternetExplorer" = [ "Win32_Web" ];
         };
-        resolvedDefaultFeatures = [ "Win32" "Win32_Foundation" "Win32_NetworkManagement" "Win32_NetworkManagement_IpHelper" "Win32_Networking" "Win32_Networking_WinSock" "Win32_Security" "Win32_Security_Authentication" "Win32_Security_Authentication_Identity" "Win32_Security_Credentials" "Win32_Security_Cryptography" "Win32_Storage" "Win32_Storage_FileSystem" "Win32_System" "Win32_System_Console" "Win32_System_Diagnostics" "Win32_System_Diagnostics_Debug" "Win32_System_IO" "Win32_System_Memory" "Win32_System_Pipes" "Win32_System_SystemServices" "Win32_System_Threading" "Win32_System_WindowsProgramming" "default" ];
+        resolvedDefaultFeatures = [ "Win32" "Win32_Foundation" "Win32_NetworkManagement" "Win32_NetworkManagement_IpHelper" "Win32_Networking" "Win32_Networking_WinSock" "Win32_Security" "Win32_Security_Authentication" "Win32_Security_Authentication_Identity" "Win32_Security_Credentials" "Win32_Security_Cryptography" "Win32_Storage" "Win32_Storage_FileSystem" "Win32_System" "Win32_System_Console" "Win32_System_Diagnostics" "Win32_System_Diagnostics_Debug" "Win32_System_IO" "Win32_System_Memory" "Win32_System_Pipes" "Win32_System_Registry" "Win32_System_SystemServices" "Win32_System_Threading" "Win32_System_Time" "Win32_System_WindowsProgramming" "default" ];
       };
       "windows-targets 0.42.2" = rec {
         crateName = "windows-targets";
@@ -11269,6 +11848,31 @@ rec {
         ];
 
       };
+      "winreg" = rec {
+        crateName = "winreg";
+        version = "0.50.0";
+        edition = "2018";
+        sha256 = "1cddmp929k882mdh6i9f2as848f13qqna6czwsqzkh1pqnr5fkjj";
+        authors = [
+          "Igor Shaula <gentoo90@gmail.com>"
+        ];
+        dependencies = [
+          {
+            name = "cfg-if";
+            packageId = "cfg-if";
+          }
+          {
+            name = "windows-sys";
+            packageId = "windows-sys 0.48.0";
+            features = [ "Win32_Foundation" "Win32_System_Time" "Win32_System_Registry" "Win32_Security" "Win32_Storage_FileSystem" "Win32_System_Diagnostics_Debug" ];
+          }
+        ];
+        features = {
+          "chrono" = [ "dep:chrono" ];
+          "serde" = [ "dep:serde" ];
+          "serialization-serde" = [ "transactions" "serde" ];
+        };
+      };
       "wu-manber" = rec {
         crateName = "wu-manber";
         version = "0.1.0";
@@ -11296,6 +11900,27 @@ rec {
         ];
 
       };
+      "xz2" = rec {
+        crateName = "xz2";
+        version = "0.1.7";
+        edition = "2018";
+        sha256 = "1qk7nzpblizvayyq4xzi4b0zacmmbqr6vb9fc0v1avyp17f4931q";
+        authors = [
+          "Alex Crichton <alex@alexcrichton.com>"
+        ];
+        dependencies = [
+          {
+            name = "lzma-sys";
+            packageId = "lzma-sys";
+          }
+        ];
+        features = {
+          "futures" = [ "dep:futures" ];
+          "static" = [ "lzma-sys/static" ];
+          "tokio" = [ "tokio-io" "futures" ];
+          "tokio-io" = [ "dep:tokio-io" ];
+        };
+      };
       "yansi" = rec {
         crateName = "yansi";
         version = "0.5.1";
diff --git a/tvix/store/Cargo.toml b/tvix/store/Cargo.toml
index c55eb80f4dc3..d5ea10a5b70b 100644
--- a/tvix/store/Cargo.toml
+++ b/tvix/store/Cargo.toml
@@ -32,6 +32,8 @@ tvix-castore = { path = "../castore" }
 url = "2.4.0"
 walkdir = "2.4.0"
 async-recursion = "1.0.5"
+reqwest = { version = "0.11.22", features = ["rustls-tls", "stream"], default-features = false }
+xz2 = "0.1.7"
 
 [dependencies.fuse-backend-rs]
 optional = true
diff --git a/tvix/store/src/pathinfoservice/from_addr.rs b/tvix/store/src/pathinfoservice/from_addr.rs
index 0f1f8d5c96a6..e7faf20144bb 100644
--- a/tvix/store/src/pathinfoservice/from_addr.rs
+++ b/tvix/store/src/pathinfoservice/from_addr.rs
@@ -1,6 +1,9 @@
 use crate::proto::path_info_service_client::PathInfoServiceClient;
 
-use super::{GRPCPathInfoService, MemoryPathInfoService, PathInfoService, SledPathInfoService};
+use super::{
+    GRPCPathInfoService, MemoryPathInfoService, NixHTTPPathInfoService, PathInfoService,
+    SledPathInfoService,
+};
 
 use std::sync::Arc;
 use tvix_castore::{blobservice::BlobService, directoryservice::DirectoryService, Error};
@@ -62,6 +65,16 @@ pub async fn from_addr(
             SledPathInfoService::new(url.path().into(), blob_service, directory_service)
                 .map_err(|e| Error::StorageError(e.to_string()))?,
         ));
+    } else if url.scheme() == "nix+http" || url.scheme() == "nix+https" {
+        // Stringify the URL and remove the nix+ prefix.
+        // We can't use `url.set_scheme(rest)`, as it disallows
+        // setting something http(s) that previously wasn't.
+        let url = Url::parse(url.to_string().strip_prefix("nix+").unwrap()).unwrap();
+        Arc::new(NixHTTPPathInfoService::new(
+            url,
+            blob_service,
+            directory_service,
+        ))
     } else if url.scheme().starts_with("grpc+") {
         // schemes starting with grpc+ go to the GRPCPathInfoService.
         //   That's normally grpc+unix for unix sockets, and grpc+http(s) for the HTTP counterparts.
@@ -113,6 +126,14 @@ mod tests {
     #[test_case("memory:///", false; "memory invalid root path")]
     /// This sets a memory url path to "/foo", which is invalid.
     #[test_case("memory:///foo", false; "memory invalid root path foo")]
+    /// Correct Scheme for the cache.nixos.org binary cache.
+    #[test_case("nix+https://cache.nixos.org", true; "correct nix+https")]
+    /// Correct Scheme for the cache.nixos.org binary cache (HTTP URL).
+    #[test_case("nix+http://cache.nixos.org", true; "correct nix+http")]
+    /// Correct Scheme for Nix HTTP Binary cache, with a subpath.
+    #[test_case("nix+http://192.0.2.1/foo", true; "correct nix http with subpath")]
+    /// Correct Scheme for Nix HTTP Binary cache, with a subpath and port.
+    #[test_case("nix+http://[::1]:8080/foo", true; "correct nix http with subpath and port")]
     /// Correct scheme to connect to a unix socket.
     #[test_case("grpc+unix:///path/to/somewhere", true; "grpc valid unix socket")]
     /// Correct scheme for unix socket, but setting a host too, which is invalid.
@@ -127,11 +148,8 @@ mod tests {
     #[test_case("grpc+http://localhost/some-path", false; "grpc valid invalid host and path")]
     #[tokio::test]
     async fn test_from_addr_tokio(uri_str: &str, is_ok: bool) {
-        assert_eq!(
-            from_addr(uri_str, gen_blob_service(), gen_directory_service())
-                .await
-                .is_ok(),
-            is_ok
-        )
+        let resp = from_addr(uri_str, gen_blob_service(), gen_directory_service()).await;
+
+        assert_eq!(resp.is_ok(), is_ok);
     }
 }
diff --git a/tvix/store/src/pathinfoservice/mod.rs b/tvix/store/src/pathinfoservice/mod.rs
index 3fde10179b36..5faa0900a0b0 100644
--- a/tvix/store/src/pathinfoservice/mod.rs
+++ b/tvix/store/src/pathinfoservice/mod.rs
@@ -1,6 +1,7 @@
 mod from_addr;
 mod grpc;
 mod memory;
+mod nix_http;
 mod sled;
 
 use futures::Stream;
@@ -14,6 +15,7 @@ use crate::proto::PathInfo;
 pub use self::from_addr::from_addr;
 pub use self::grpc::GRPCPathInfoService;
 pub use self::memory::MemoryPathInfoService;
+pub use self::nix_http::NixHTTPPathInfoService;
 pub use self::sled::SledPathInfoService;
 
 /// The base trait all PathInfo services need to implement.
diff --git a/tvix/store/src/pathinfoservice/nix_http.rs b/tvix/store/src/pathinfoservice/nix_http.rs
new file mode 100644
index 000000000000..49cd515ce913
--- /dev/null
+++ b/tvix/store/src/pathinfoservice/nix_http.rs
@@ -0,0 +1,213 @@
+use std::{
+    io::{self, BufRead},
+    pin::Pin,
+    sync::Arc,
+};
+
+use data_encoding::BASE64;
+use futures::{Stream, TryStreamExt};
+use nix_compat::{narinfo::NarInfo, nixbase32};
+use reqwest::StatusCode;
+use tonic::async_trait;
+use tracing::{debug, instrument, warn};
+use tvix_castore::{
+    blobservice::BlobService, directoryservice::DirectoryService, proto as castorepb, Error,
+};
+
+use crate::proto::PathInfo;
+
+use super::PathInfoService;
+
+/// NixHTTPPathInfoService acts as a bridge in between the Nix HTTP Binary cache
+/// protocol provided by Nix binary caches such as cache.nixos.org, and the Tvix
+/// Store Model.
+/// It implements the [PathInfoService] trait in an interesting way:
+/// Every [PathInfoService::get] fetches the .narinfo and referred NAR file,
+/// inserting components into a [BlobService] and [DirectoryService], then
+/// returning a [PathInfo] struct with the root.
+///
+/// Due to this being quite a costly operation, clients are expected to layer
+/// this service with store composition, so they're only ingested once.
+///
+/// The client is expected to be (indirectly) using the same [BlobService] and
+/// [DirectoryService], so able to fetch referred Directories and Blobs.
+/// [PathInfoService::put] and [PathInfoService::nar] are not implemented and
+/// return an error if called.
+/// TODO: what about reading from nix-cache-info?
+pub struct NixHTTPPathInfoService {
+    base_url: url::Url,
+    http_client: reqwest::Client,
+
+    blob_service: Arc<dyn BlobService>,
+    directory_service: Arc<dyn DirectoryService>,
+}
+
+impl NixHTTPPathInfoService {
+    pub fn new(
+        base_url: url::Url,
+        blob_service: Arc<dyn BlobService>,
+        directory_service: Arc<dyn DirectoryService>,
+    ) -> Self {
+        Self {
+            base_url,
+            http_client: reqwest::Client::new(),
+            blob_service,
+            directory_service,
+        }
+    }
+}
+
+#[async_trait]
+impl PathInfoService for NixHTTPPathInfoService {
+    #[instrument(skip_all, err, fields(path.digest=BASE64.encode(&digest)))]
+    async fn get(&self, digest: [u8; 20]) -> Result<Option<PathInfo>, Error> {
+        let narinfo_url = self
+            .base_url
+            .join(&format!("{}.narinfo", nixbase32::encode(&digest)))
+            .map_err(|e| {
+                warn!(e = %e, "unable to join URL");
+                io::Error::new(io::ErrorKind::InvalidInput, "unable to join url")
+            })?;
+
+        debug!(narinfo_url= %narinfo_url, "constructed NARInfo url");
+
+        let resp = self
+            .http_client
+            .get(narinfo_url)
+            .send()
+            .await
+            .map_err(|e| {
+                warn!(e=%e,"unable to send NARInfo request");
+                io::Error::new(
+                    io::ErrorKind::InvalidInput,
+                    "unable to send NARInfo request",
+                )
+            })?;
+
+        // In the case of a 404, return a NotFound.
+        // We also return a NotFound in case of a 403 - this is to match the behaviour as Nix,
+        // when querying nix-cache.s3.amazonaws.com directly, rather than cache.nixos.org.
+        if resp.status() == StatusCode::NOT_FOUND || resp.status() == StatusCode::FORBIDDEN {
+            return Ok(None);
+        }
+
+        let narinfo_str = resp.text().await.map_err(|e| {
+            warn!(e=%e,"unable to decode response as string");
+            io::Error::new(
+                io::ErrorKind::InvalidData,
+                "unable to decode response as string",
+            )
+        })?;
+
+        // parse the received narinfo
+        let narinfo = NarInfo::parse(&narinfo_str).map_err(|e| {
+            warn!(e=%e,"unable to parse response as NarInfo");
+            io::Error::new(
+                io::ErrorKind::InvalidData,
+                "unable to parse response as NarInfo",
+            )
+        })?;
+
+        // Convert to a (sparse) PathInfo. We still need to populate the node field,
+        // and for this we need to download the NAR file.
+        // FUTUREWORK: Keep some database around mapping from narsha256 to
+        // (unnamed) rootnode, so we can use that (and the name from the
+        // StorePath) and avoid downloading the same NAR a second time.
+        let pathinfo: PathInfo = (&narinfo).into();
+
+        // create a request for the NAR file itself.
+        let nar_url = self.base_url.join(narinfo.url).map_err(|e| {
+            warn!(e = %e, "unable to join URL");
+            io::Error::new(io::ErrorKind::InvalidInput, "unable to join url")
+        })?;
+        debug!(nar_url= %nar_url, "constructed NAR url");
+
+        let resp = self
+            .http_client
+            .get(nar_url.clone())
+            .send()
+            .await
+            .map_err(|e| {
+                warn!(e=%e,"unable to send NAR request");
+                io::Error::new(io::ErrorKind::InvalidInput, "unable to send NAR request")
+            })?;
+
+        // if the request is not successful, return an error.
+        if !resp.status().is_success() {
+            return Err(Error::StorageError(format!(
+                "unable to retrieve NAR at {}, status {}",
+                nar_url,
+                resp.status()
+            )));
+        }
+
+        // get an AsyncRead of the response body.
+        let async_r = tokio_util::io::StreamReader::new(resp.bytes_stream().map_err(|e| {
+            let e = e.without_url();
+            warn!(e=%e, "failed to get response body");
+            io::Error::new(io::ErrorKind::BrokenPipe, e.to_string())
+        }));
+        let sync_r = std::io::BufReader::new(tokio_util::io::SyncIoBridge::new(async_r));
+
+        // handle decompression, by wrapping the reader.
+        let mut sync_r: Box<dyn BufRead + Send> = match narinfo.compression {
+            Some("none") => Box::new(sync_r),
+            Some("xz") => Box::new(std::io::BufReader::new(xz2::read::XzDecoder::new(sync_r))),
+            Some(comp) => {
+                return Err(Error::InvalidRequest(
+                    format!("unsupported compression: {}", comp).to_string(),
+                ))
+            }
+            None => {
+                return Err(Error::InvalidRequest(
+                    "unsupported compression: bzip2".to_string(),
+                ))
+            }
+        };
+
+        let res = tokio::task::spawn_blocking({
+            let blob_service = self.blob_service.clone();
+            let directory_service = self.directory_service.clone();
+            move || crate::nar::read_nar(&mut sync_r, blob_service, directory_service)
+        })
+        .await
+        .unwrap();
+
+        match res {
+            Ok(root_node) => Ok(Some(PathInfo {
+                node: Some(castorepb::Node {
+                    // set the name of the root node to the digest-name of the store path.
+                    node: Some(root_node.rename(narinfo.store_path.to_string().to_owned().into())),
+                }),
+                references: pathinfo.references,
+                narinfo: pathinfo.narinfo,
+            })),
+            Err(e) => Err(e.into()),
+        }
+    }
+
+    #[instrument(skip_all, fields(path_info=?_path_info))]
+    async fn put(&self, _path_info: PathInfo) -> Result<PathInfo, Error> {
+        Err(Error::InvalidRequest(
+            "put not supported for this backend".to_string(),
+        ))
+    }
+
+    #[instrument(skip_all, fields(root_node=?root_node))]
+    async fn calculate_nar(
+        &self,
+        root_node: &castorepb::node::Node,
+    ) -> Result<(u64, [u8; 32]), Error> {
+        Err(Error::InvalidRequest(
+            "calculate_nar not supported for this backend".to_string(),
+        ))
+    }
+
+    fn list(&self) -> Pin<Box<dyn Stream<Item = Result<PathInfo, Error>> + Send>> {
+        Box::pin(futures::stream::once(async {
+            Err(Error::InvalidRequest(
+                "list not supported for this backend".to_string(),
+            ))
+        }))
+    }
+}