feat(tvix/store/blobsvc): add from_addr r/6302

This allows constructing blob stores with a URL syntax at runtime,
by passing the --blob-service-addr arg.

We probably still want to have some builder pattern here, to allow
additional schemes to be registered.

Change-Id: Ie588ff7a7c6fb64c9474dfbd2e4bc5f168dfd778
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8742
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI

9 files changed, 657 insertions, 24 deletions

diff --git a/tvix/Cargo.lock b/tvix/Cargo.lock
index dbc572b01a..7bcf60dcec 100644
--- a/tvix/Cargo.lock
+++ b/tvix/Cargo.lock
@@ -725,6 +725,15 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
 
 [[package]]
+name = "form_urlencoded"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a62bc1cf6f830c2ec14a513a9fb124d0a213a629668a4186f329db21fe045652"
+dependencies = [
+ "percent-encoding",
+]
+
+[[package]]
 name = "fs2"
 version = "0.4.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1043,6 +1052,16 @@ dependencies = [
 ]
 
 [[package]]
+name = "idna"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7d20d6b07bfbc108882d88ed8e37d39636dcc260e15e30c45e6ba089610b917c"
+dependencies = [
+ "unicode-bidi",
+ "unicode-normalization",
+]
+
+[[package]]
 name = "imbl"
 version = "2.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -1458,9 +1477,9 @@ checksum = "ecba01bf2678719532c5e3059e0b5f0811273d94b397088b82e3bd0a78c78fdd"
 
 [[package]]
 name = "percent-encoding"
-version = "2.2.0"
+version = "2.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "478c572c3d73181ff3c2539045f6eb99e5491218eae919370993b890cdbdd98e"
+checksum = "9b2a4787296e9989611394c33f193f676704af1686e70b8f8033ab5ba9a35a94"
 
 [[package]]
 name = "petgraph"
@@ -2370,6 +2389,21 @@ dependencies = [
 ]
 
 [[package]]
+name = "tinyvec"
+version = "1.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "87cc5ceb3875bb20c2890005a4e226a4651264a5c75edb2421b52861a0a0cb50"
+dependencies = [
+ "tinyvec_macros",
+]
+
+[[package]]
+name = "tinyvec_macros"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1f3ccbac311fea05f86f61904b462b55fb3df8837a366dfc601a0161d0532f20"
+
+[[package]]
 name = "tokio"
 version = "1.28.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -2761,6 +2795,7 @@ dependencies = [
  "tracing",
  "tracing-subscriber",
  "tvix-eval",
+ "url",
  "walkdir",
 ]
 
@@ -2777,12 +2812,27 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "eaea85b334db583fe3274d12b4cd1880032beab409c0d774be044d4480ab9a94"
 
 [[package]]
+name = "unicode-bidi"
+version = "0.3.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "92888ba5573ff080736b3648696b70cafad7d250551175acbaa4e0385b3e1460"
+
+[[package]]
 name = "unicode-ident"
 version = "1.0.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e5464a87b239f13a63a501f2701565754bae92d243d4bb7eb12f6d57d2269bf4"
 
 [[package]]
+name = "unicode-normalization"
+version = "0.1.22"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c5713f0fc4b5db668a2ac63cdb7bb4469d8c9fed047b1d0292cc7b0ce2ba921"
+dependencies = [
+ "tinyvec",
+]
+
+[[package]]
 name = "unicode-segmentation"
 version = "1.10.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -2801,6 +2851,17 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fc72304796d0818e357ead4e000d19c9c174ab23dc11093ac919054d20a6a7fc"
 
 [[package]]
+name = "url"
+version = "2.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "50bff7831e19200a85b17131d085c25d7811bc4e186efdaf54bbd132994a88cb"
+dependencies = [
+ "form_urlencoded",
+ "idna",
+ "percent-encoding",
+]
+
+[[package]]
 name = "users"
 version = "0.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
diff --git a/tvix/Cargo.nix b/tvix/Cargo.nix
index 30a845dd9c..df2b4495ae 100644
--- a/tvix/Cargo.nix
+++ b/tvix/Cargo.nix
@@ -2014,6 +2014,28 @@ rec {
         };
         resolvedDefaultFeatures = [ "default" "std" ];
       };
+      "form_urlencoded" = rec {
+        crateName = "form_urlencoded";
+        version = "1.2.0";
+        edition = "2018";
+        sha256 = "0ljn0kz23nr9yf3432k656k178nh4jqryfji9b0jw343dz7w2ax6";
+        authors = [
+          "The rust-url developers"
+        ];
+        dependencies = [
+          {
+            name = "percent-encoding";
+            packageId = "percent-encoding";
+            usesDefaultFeatures = false;
+          }
+        ];
+        features = {
+          "alloc" = [ "percent-encoding/alloc" ];
+          "default" = [ "std" ];
+          "std" = [ "alloc" "percent-encoding/std" ];
+        };
+        resolvedDefaultFeatures = [ "alloc" "default" "std" ];
+      };
       "fs2" = rec {
         crateName = "fs2";
         version = "0.4.3";
@@ -2956,6 +2978,33 @@ rec {
         ];
 
       };
+      "idna" = rec {
+        crateName = "idna";
+        version = "0.4.0";
+        edition = "2018";
+        sha256 = "0z4i1dhqk83bbv230pp1c31dqdlnscvqxvc85n40ihgvgfqdc83x";
+        authors = [
+          "The rust-url developers"
+        ];
+        dependencies = [
+          {
+            name = "unicode-bidi";
+            packageId = "unicode-bidi";
+            usesDefaultFeatures = false;
+            features = [ "hardcoded-data" ];
+          }
+          {
+            name = "unicode-normalization";
+            packageId = "unicode-normalization";
+            usesDefaultFeatures = false;
+          }
+        ];
+        features = {
+          "default" = [ "std" ];
+          "std" = [ "alloc" "unicode-bidi/std" "unicode-normalization/std" ];
+        };
+        resolvedDefaultFeatures = [ "alloc" "default" "std" ];
+      };
       "imbl" = rec {
         crateName = "imbl";
         version = "2.0.0";
@@ -4144,16 +4193,17 @@ rec {
       };
       "percent-encoding" = rec {
         crateName = "percent-encoding";
-        version = "2.2.0";
+        version = "2.3.0";
         edition = "2018";
-        sha256 = "13nrpp6r1f4k14viksga3094krcrxgv4b42kqbriy63k7ln5g327";
+        sha256 = "152slflmparkh27hprw62sph8rv77wckzhwl2dhqk6bf563lfalv";
         authors = [
           "The rust-url developers"
         ];
         features = {
-          "default" = [ "alloc" ];
+          "default" = [ "std" ];
+          "std" = [ "alloc" ];
         };
-        resolvedDefaultFeatures = [ "alloc" "default" ];
+        resolvedDefaultFeatures = [ "alloc" "default" "std" ];
       };
       "petgraph" = rec {
         crateName = "petgraph";
@@ -6721,6 +6771,43 @@ rec {
         ];
 
       };
+      "tinyvec" = rec {
+        crateName = "tinyvec";
+        version = "1.6.0";
+        edition = "2018";
+        sha256 = "0l6bl2h62a5m44jdnpn7lmj14rd44via8180i7121fvm73mmrk47";
+        authors = [
+          "Lokathor <zefria@gmail.com>"
+        ];
+        dependencies = [
+          {
+            name = "tinyvec_macros";
+            packageId = "tinyvec_macros";
+            optional = true;
+          }
+        ];
+        features = {
+          "alloc" = [ "tinyvec_macros" ];
+          "arbitrary" = [ "dep:arbitrary" ];
+          "real_blackbox" = [ "criterion/real_blackbox" ];
+          "rustc_1_55" = [ "rustc_1_40" ];
+          "rustc_1_57" = [ "rustc_1_55" ];
+          "serde" = [ "dep:serde" ];
+          "std" = [ "alloc" ];
+          "tinyvec_macros" = [ "dep:tinyvec_macros" ];
+        };
+        resolvedDefaultFeatures = [ "alloc" "default" "tinyvec_macros" ];
+      };
+      "tinyvec_macros" = rec {
+        crateName = "tinyvec_macros";
+        version = "0.1.1";
+        edition = "2018";
+        sha256 = "081gag86208sc3y6sdkshgw3vysm5d34p431dzw0bshz66ncng0z";
+        authors = [
+          "Soveu <marx.tomasz@gmail.com>"
+        ];
+
+      };
       "tokio" = rec {
         crateName = "tokio";
         version = "1.28.0";
@@ -8220,6 +8307,10 @@ rec {
             packageId = "tvix-eval";
           }
           {
+            name = "url";
+            packageId = "url";
+          }
+          {
             name = "walkdir";
             packageId = "walkdir";
           }
@@ -8278,6 +8369,25 @@ rec {
         sha256 = "154smf048k84prsdgh09nkm2n0w0336v84jd4zikyn6v6jrqbspa";
 
       };
+      "unicode-bidi" = rec {
+        crateName = "unicode-bidi";
+        version = "0.3.13";
+        edition = "2018";
+        sha256 = "0q0l7rdkiq54pan7a4ama39dgynaf1mnjj1nddrq1w1zayjqp24j";
+        libName = "unicode_bidi";
+        authors = [
+          "The Servo Project Developers"
+        ];
+        features = {
+          "default" = [ "std" "hardcoded-data" ];
+          "flame" = [ "dep:flame" ];
+          "flame_it" = [ "flame" "flamer" ];
+          "flamer" = [ "dep:flamer" ];
+          "serde" = [ "dep:serde" ];
+          "with_serde" = [ "serde" ];
+        };
+        resolvedDefaultFeatures = [ "hardcoded-data" "std" ];
+      };
       "unicode-ident" = rec {
         crateName = "unicode-ident";
         version = "1.0.8";
@@ -8288,6 +8398,27 @@ rec {
         ];
 
       };
+      "unicode-normalization" = rec {
+        crateName = "unicode-normalization";
+        version = "0.1.22";
+        edition = "2018";
+        sha256 = "08d95g7b1irc578b2iyhzv4xhsa4pfvwsqxcl9lbcpabzkq16msw";
+        authors = [
+          "kwantam <kwantam@gmail.com>"
+          "Manish Goregaokar <manishsmail@gmail.com>"
+        ];
+        dependencies = [
+          {
+            name = "tinyvec";
+            packageId = "tinyvec";
+            features = [ "alloc" ];
+          }
+        ];
+        features = {
+          "default" = [ "std" ];
+        };
+        resolvedDefaultFeatures = [ "std" ];
+      };
       "unicode-segmentation" = rec {
         crateName = "unicode-segmentation";
         version = "1.10.1";
@@ -8328,6 +8459,33 @@ rec {
         features = { };
         resolvedDefaultFeatures = [ "default" ];
       };
+      "url" = rec {
+        crateName = "url";
+        version = "2.4.0";
+        edition = "2018";
+        sha256 = "1jw89ack5ldvajpzsvhq9sy12y2xqa2x0cbin62hl80r3s1zggsh";
+        authors = [
+          "The rust-url developers"
+        ];
+        dependencies = [
+          {
+            name = "form_urlencoded";
+            packageId = "form_urlencoded";
+          }
+          {
+            name = "idna";
+            packageId = "idna";
+          }
+          {
+            name = "percent-encoding";
+            packageId = "percent-encoding";
+          }
+        ];
+        features = {
+          "serde" = [ "dep:serde" ];
+        };
+        resolvedDefaultFeatures = [ "default" ];
+      };
       "users" = rec {
         crateName = "users";
         version = "0.11.0";
diff --git a/tvix/store/Cargo.toml b/tvix/store/Cargo.toml
index 3b2765f992..db4e2b3c27 100644
--- a/tvix/store/Cargo.toml
+++ b/tvix/store/Cargo.toml
@@ -29,6 +29,7 @@ futures = "0.3.28"
 bytes = "1.4.0"
 smol_str = "0.2.0"
 serde_json = "1.0"
+url = "2.4.0"
 
 [dependencies.fuser]
 optional = true
diff --git a/tvix/store/src/bin/tvix-store.rs b/tvix/store/src/bin/tvix-store.rs
index b95f408a55..6e2424a7e5 100644
--- a/tvix/store/src/bin/tvix-store.rs
+++ b/tvix/store/src/bin/tvix-store.rs
@@ -6,16 +6,13 @@ use std::path::Path;
 use std::path::PathBuf;
 use std::sync::Arc;
 use tracing_subscriber::prelude::*;
-use tvix_store::blobservice::BlobService;
-use tvix_store::blobservice::GRPCBlobService;
-use tvix_store::blobservice::SledBlobService;
+use tvix_store::blobservice;
 use tvix_store::directoryservice::DirectoryService;
 use tvix_store::directoryservice::GRPCDirectoryService;
 use tvix_store::directoryservice::SledDirectoryService;
 use tvix_store::pathinfoservice::GRPCPathInfoService;
 use tvix_store::pathinfoservice::PathInfoService;
 use tvix_store::pathinfoservice::SledPathInfoService;
-use tvix_store::proto::blob_service_client::BlobServiceClient;
 use tvix_store::proto::blob_service_server::BlobServiceServer;
 use tvix_store::proto::directory_service_client::DirectoryServiceClient;
 use tvix_store::proto::directory_service_server::DirectoryServiceServer;
@@ -55,17 +52,26 @@ enum Commands {
     Daemon {
         #[arg(long, short = 'l')]
         listen_address: Option<String>,
+
+        #[arg(long, env, default_value = "sled:///var/lib/tvix-store/blobs.sled")]
+        blob_service_addr: String,
     },
     /// Imports a list of paths into the store (not using the daemon)
     Import {
         #[clap(value_name = "PATH")]
         paths: Vec<PathBuf>,
+
+        #[arg(long, env, default_value = "grpc+http://[::1]:8000")]
+        blob_service_addr: String,
     },
     /// Mounts a tvix-store at the given mountpoint
     #[cfg(feature = "fuse")]
     Mount {
         #[clap(value_name = "PATH")]
         dest: PathBuf,
+
+        #[arg(long, env, default_value = "grpc+http://[::1]:8000")]
+        blob_service_addr: String,
     },
 }
 
@@ -99,10 +105,12 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
     tracing::subscriber::set_global_default(subscriber).expect("Unable to set global subscriber");
 
     match cli.command {
-        Commands::Daemon { listen_address } => {
+        Commands::Daemon {
+            listen_address,
+            blob_service_addr,
+        } => {
             // initialize stores
-            let blob_service: Arc<dyn BlobService> =
-                Arc::new(SledBlobService::new("blobs.sled".into())?);
+            let blob_service = blobservice::from_addr(&blob_service_addr).await?;
             let directory_service: Arc<dyn DirectoryService> =
                 Arc::new(SledDirectoryService::new("directories.sled".into())?);
             let path_info_service: Arc<dyn PathInfoService> = Arc::new(SledPathInfoService::new(
@@ -142,10 +150,12 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 
             router.serve(listen_address).await?;
         }
-        Commands::Import { paths } => {
-            let blob_service = GRPCBlobService::from_client(
-                BlobServiceClient::connect("http://[::1]:8000").await?,
-            );
+        Commands::Import {
+            paths,
+            blob_service_addr,
+        } => {
+            let blob_service = blobservice::from_addr(&blob_service_addr).await?;
+
             let directory_service = GRPCDirectoryService::from_client(
                 DirectoryServiceClient::connect("http://[::1]:8000").await?,
             );
@@ -155,7 +165,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
                 GRPCPathInfoService::from_client(path_info_service_client.clone());
 
             let io = Arc::new(TvixStoreIO::new(
-                Arc::new(blob_service),
+                blob_service,
                 Arc::new(directory_service),
                 Arc::new(path_info_service),
             ));
@@ -178,10 +188,12 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
             try_join_all(tasks).await?;
         }
         #[cfg(feature = "fuse")]
-        Commands::Mount { dest } => {
-            let blob_service = GRPCBlobService::from_client(
-                BlobServiceClient::connect("http://[::1]:8000").await?,
-            );
+        Commands::Mount {
+            dest,
+            blob_service_addr,
+        } => {
+            let blob_service = blobservice::from_addr(&blob_service_addr).await?;
+
             let directory_service = GRPCDirectoryService::from_client(
                 DirectoryServiceClient::connect("http://[::1]:8000").await?,
             );
@@ -192,7 +204,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 
             tokio::task::spawn_blocking(move || {
                 let f = FUSE::new(
-                    Arc::new(blob_service),
+                    blob_service,
                     Arc::new(directory_service),
                     Arc::new(path_info_service),
                 );
diff --git a/tvix/store/src/blobservice/from_addr.rs b/tvix/store/src/blobservice/from_addr.rs
new file mode 100644
index 0000000000..761498041d
--- /dev/null
+++ b/tvix/store/src/blobservice/from_addr.rs
@@ -0,0 +1,31 @@
+use std::sync::Arc;
+use url::Url;
+
+use super::{BlobService, GRPCBlobService, MemoryBlobService, SledBlobService};
+
+/// Constructs a new instance of a [BlobService] from an URI.
+///
+/// The following schemes are supported by the following services:
+/// - `memory://` ([MemoryBlobService])
+/// - `sled://` ([SledBlobService])
+/// - `grpc+*://` ([GRPCBlobService])
+///
+/// See their [from_url] methods for more details about their syntax.
+pub async fn from_addr(uri: &str) -> Result<Arc<dyn BlobService>, crate::Error> {
+    let url = Url::parse(uri).map_err(|e| {
+        crate::Error::StorageError(format!("unable to parse url: {}", e.to_string()))
+    })?;
+
+    Ok(if url.scheme() == "memory" {
+        Arc::new(MemoryBlobService::from_url(&url)?)
+    } else if url.scheme() == "sled" {
+        Arc::new(SledBlobService::from_url(&url)?)
+    } else if url.scheme().starts_with("grpc+") {
+        Arc::new(GRPCBlobService::from_url(&url)?)
+    } else {
+        Err(crate::Error::StorageError(format!(
+            "unknown scheme: {}",
+            url.scheme()
+        )))?
+    })
+}
diff --git a/tvix/store/src/blobservice/grpc.rs b/tvix/store/src/blobservice/grpc.rs
index fbf2dfe72e..a2c7f56f0d 100644
--- a/tvix/store/src/blobservice/grpc.rs
+++ b/tvix/store/src/blobservice/grpc.rs
@@ -2,7 +2,7 @@ use super::{BlobService, BlobWriter};
 use crate::{proto, B3Digest};
 use futures::sink::{SinkExt, SinkMapErr};
 use std::{collections::VecDeque, io};
-use tokio::task::JoinHandle;
+use tokio::{net::UnixStream, task::JoinHandle};
 use tokio_stream::{wrappers::ReceiverStream, StreamExt};
 use tokio_util::{
     io::{CopyToBytes, SinkWriter, SyncIoBridge},
@@ -36,6 +36,58 @@ impl GRPCBlobService {
 }
 
 impl BlobService for GRPCBlobService {
+    /// Constructs a [GRPCBlobService] from the passed [url::Url]:
+    /// - scheme has to match `grpc+*://`.
+    ///   That's normally grpc+unix for unix sockets, and grpc+http(s) for the HTTP counterparts.
+    /// - In the case of unix sockets, there must be a path, but may not be a host.
+    /// - In the case of non-unix sockets, there must be a host, but no path.
+    fn from_url(url: &url::Url) -> Result<Self, crate::Error> {
+        // Start checking for the scheme to start with grpc+.
+        match url.scheme().strip_prefix("grpc+") {
+            None => Err(crate::Error::StorageError("invalid scheme".to_string())),
+            Some(rest) => {
+                if rest == "unix" {
+                    if url.host_str().is_some() {
+                        return Err(crate::Error::StorageError(
+                            "host may not be set".to_string(),
+                        ));
+                    }
+                    let path = url.path().to_string();
+                    let channel = tonic::transport::Endpoint::try_from("http://[::]:50051") // doesn't matter
+                        .unwrap()
+                        .connect_with_connector_lazy(tower::service_fn(
+                            move |_: tonic::transport::Uri| UnixStream::connect(path.clone()),
+                        ));
+                    let grpc_client = proto::blob_service_client::BlobServiceClient::new(channel);
+                    Ok(Self::from_client(grpc_client))
+                } else {
+                    // ensure path is empty, not supported with gRPC.
+                    if !url.path().is_empty() {
+                        return Err(crate::Error::StorageError(
+                            "path may not be set".to_string(),
+                        ));
+                    }
+
+                    // clone the uri, and drop the grpc+ from the scheme.
+                    // Recreate a new uri with the `grpc+` prefix dropped from the scheme.
+                    // We can't use `url.set_scheme(rest)`, as it disallows
+                    // setting something http(s) that previously wasn't.
+                    let url = {
+                        let url_str = url.to_string();
+                        let s_stripped = url_str.strip_prefix("grpc+").unwrap();
+                        url::Url::parse(s_stripped).unwrap()
+                    };
+                    let channel = tonic::transport::Endpoint::try_from(url.to_string())
+                        .unwrap()
+                        .connect_lazy();
+
+                    let grpc_client = proto::blob_service_client::BlobServiceClient::new(channel);
+                    Ok(Self::from_client(grpc_client))
+                }
+            }
+        }
+    }
+
     #[instrument(skip(self, digest), fields(blob.digest=%digest))]
     fn has(&self, digest: &B3Digest) -> Result<bool, crate::Error> {
         // Get a new handle to the gRPC client, and copy the digest.
@@ -236,3 +288,148 @@ impl io::Write for GRPCBlobWriter {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use std::sync::Arc;
+    use std::thread;
+
+    use tempfile::TempDir;
+    use tokio::net::UnixListener;
+    use tokio::task;
+    use tokio::time;
+    use tokio_stream::wrappers::UnixListenerStream;
+
+    use crate::blobservice::MemoryBlobService;
+    use crate::proto::GRPCBlobServiceWrapper;
+    use crate::tests::fixtures;
+
+    use super::BlobService;
+    use super::GRPCBlobService;
+
+    /// This uses the wrong scheme
+    #[test]
+    fn test_invalid_scheme() {
+        let url = url::Url::parse("http://foo.example/test").expect("must parse");
+
+        assert!(GRPCBlobService::from_url(&url).is_err());
+    }
+
+    /// This uses the correct scheme for a unix socket.
+    /// The fact that /path/to/somewhere doesn't exist yet is no problem, because we connect lazily.
+    #[tokio::test]
+    async fn test_valid_unix_path() {
+        let url = url::Url::parse("grpc+unix:///path/to/somewhere").expect("must parse");
+
+        assert!(GRPCBlobService::from_url(&url).is_ok());
+    }
+
+    /// This uses the correct scheme for a unix socket,
+    /// but sets a host, which is unsupported.
+    #[tokio::test]
+    async fn test_invalid_unix_path_with_domain() {
+        let url =
+            url::Url::parse("grpc+unix://host.example/path/to/somewhere").expect("must parse");
+
+        assert!(GRPCBlobService::from_url(&url).is_err());
+    }
+
+    /// This uses the correct scheme for a HTTP server.
+    /// The fact that nothing is listening there is no problem, because we connect lazily.
+    #[tokio::test]
+    async fn test_valid_http() {
+        let url = url::Url::parse("grpc+http://localhost").expect("must parse");
+
+        assert!(GRPCBlobService::from_url(&url).is_ok());
+    }
+
+    /// This uses the correct scheme for a HTTPS server.
+    /// The fact that nothing is listening there is no problem, because we connect lazily.
+    #[tokio::test]
+    async fn test_valid_https() {
+        let url = url::Url::parse("grpc+https://localhost").expect("must parse");
+
+        assert!(GRPCBlobService::from_url(&url).is_ok());
+    }
+
+    /// This uses the correct scheme, but also specifies
+    /// an additional path, which is not supported for gRPC.
+    /// The fact that nothing is listening there is no problem, because we connect lazily.
+    #[tokio::test]
+    async fn test_invalid_http_with_path() {
+        let url = url::Url::parse("grpc+https://localhost/some-path").expect("must parse");
+
+        assert!(GRPCBlobService::from_url(&url).is_err());
+    }
+
+    /// This uses the correct scheme for a unix socket, and provides a server on the other side.
+    #[tokio::test]
+    async fn test_valid_unix_path_ping_pong() {
+        let tmpdir = TempDir::new().unwrap();
+        let path = tmpdir.path().join("daemon");
+
+        // let mut join_set = JoinSet::new();
+
+        // prepare a client
+        let client = {
+            let mut url = url::Url::parse("grpc+unix:///path/to/somewhere").expect("must parse");
+            url.set_path(path.to_str().unwrap());
+            GRPCBlobService::from_url(&url).expect("must succeed")
+        };
+
+        let path_copy = path.clone();
+
+        // Spin up a server, in a thread far away, which spawns its own tokio runtime,
+        // and blocks on the task.
+        thread::spawn(move || {
+            // Create the runtime
+            let rt = tokio::runtime::Runtime::new().unwrap();
+            // Get a handle from this runtime
+            let handle = rt.handle();
+
+            let task = handle.spawn(async {
+                let uds = UnixListener::bind(path_copy).unwrap();
+                let uds_stream = UnixListenerStream::new(uds);
+
+                // spin up a new server
+                let mut server = tonic::transport::Server::builder();
+                let router =
+                    server.add_service(crate::proto::blob_service_server::BlobServiceServer::new(
+                        GRPCBlobServiceWrapper::from(
+                            Arc::new(MemoryBlobService::default()) as Arc<dyn BlobService>
+                        ),
+                    ));
+                router.serve_with_incoming(uds_stream).await
+            });
+
+            handle.block_on(task)
+        });
+
+        // wait for the socket to be created
+        {
+            let mut socket_created = false;
+            for _try in 1..20 {
+                if path.exists() {
+                    socket_created = true;
+                    break;
+                }
+                tokio::time::sleep(time::Duration::from_millis(20)).await;
+            }
+
+            assert!(
+                socket_created,
+                "expected socket path to eventually get created, but never happened"
+            );
+        }
+
+        let has = task::spawn_blocking(move || {
+            println!("client has?");
+            client
+                .has(&fixtures::BLOB_A_DIGEST)
+                .expect("must not be err")
+        })
+        .await
+        .expect("must not be err");
+        assert!(!has);
+    }
+}
diff --git a/tvix/store/src/blobservice/memory.rs b/tvix/store/src/blobservice/memory.rs
index 0ea8479f87..a53f899149 100644
--- a/tvix/store/src/blobservice/memory.rs
+++ b/tvix/store/src/blobservice/memory.rs
@@ -14,6 +14,22 @@ pub struct MemoryBlobService {
 }
 
 impl BlobService for MemoryBlobService {
+    /// Constructs a [MemoryBlobService] from the passed [url::Url]:
+    /// - scheme has to be `memory://`
+    /// - there may not be a host.
+    /// - there may not be a path.
+    fn from_url(url: &url::Url) -> Result<Self, Error> {
+        if url.scheme() != "memory" {
+            return Err(crate::Error::StorageError("invalid scheme".to_string()));
+        }
+
+        if url.has_host() || !url.path().is_empty() {
+            return Err(crate::Error::StorageError("invalid url".to_string()));
+        }
+
+        Ok(Self::default())
+    }
+
     #[instrument(skip(self, digest), fields(blob.digest=%digest))]
     fn has(&self, digest: &B3Digest) -> Result<bool, Error> {
         let db = self.db.read().unwrap();
@@ -113,3 +129,49 @@ impl BlobWriter for MemoryBlobWriter {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::BlobService;
+    use super::MemoryBlobService;
+
+    /// This uses a wrong scheme.
+    #[test]
+    fn test_invalid_scheme() {
+        let url = url::Url::parse("http://foo.example/test").expect("must parse");
+
+        assert!(MemoryBlobService::from_url(&url).is_err());
+    }
+
+    /// This correctly sets the scheme, and doesn't set a path.
+    #[test]
+    fn test_valid_scheme() {
+        let url = url::Url::parse("memory://").expect("must parse");
+
+        assert!(MemoryBlobService::from_url(&url).is_ok());
+    }
+
+    /// This sets the host to `foo`
+    #[test]
+    fn test_invalid_host() {
+        let url = url::Url::parse("memory://foo").expect("must parse");
+
+        assert!(MemoryBlobService::from_url(&url).is_err());
+    }
+
+    /// This has the path "/", which is invalid.
+    #[test]
+    fn test_invalid_has_path() {
+        let url = url::Url::parse("memory:///").expect("must parse");
+
+        assert!(MemoryBlobService::from_url(&url).is_err());
+    }
+
+    /// This has the path "/foo", which is invalid.
+    #[test]
+    fn test_invalid_path2() {
+        let url = url::Url::parse("memory:///foo").expect("must parse");
+
+        assert!(MemoryBlobService::from_url(&url).is_err());
+    }
+}
diff --git a/tvix/store/src/blobservice/mod.rs b/tvix/store/src/blobservice/mod.rs
index c1bca927d7..622d058353 100644
--- a/tvix/store/src/blobservice/mod.rs
+++ b/tvix/store/src/blobservice/mod.rs
@@ -2,10 +2,12 @@ use std::io;
 
 use crate::{B3Digest, Error};
 
+mod from_addr;
 mod grpc;
 mod memory;
 mod sled;
 
+pub use self::from_addr::from_addr;
 pub use self::grpc::GRPCBlobService;
 pub use self::memory::MemoryBlobService;
 pub use self::sled::SledBlobService;
@@ -16,6 +18,11 @@ pub use self::sled::SledBlobService;
 /// Blob, which will return something implmenting io::Write, and providing a
 /// close funtion, to finalize a blob and get its digest.
 pub trait BlobService: Send + Sync {
+    /// Create a new instance by passing in a connection URL.
+    fn from_url(url: &url::Url) -> Result<Self, Error>
+    where
+        Self: Sized;
+
     /// Check if the service has the blob, by its content hash.
     fn has(&self, digest: &B3Digest) -> Result<bool, Error>;
 
diff --git a/tvix/store/src/blobservice/sled.rs b/tvix/store/src/blobservice/sled.rs
index 1ae71170e1..6b38a5e0ed 100644
--- a/tvix/store/src/blobservice/sled.rs
+++ b/tvix/store/src/blobservice/sled.rs
@@ -28,6 +28,36 @@ impl SledBlobService {
 }
 
 impl BlobService for SledBlobService {
+    /// Constructs a [SledBlobService] from the passed [url::Url]:
+    /// - scheme has to be `sled://`
+    /// - there may not be a host.
+    /// - a path to the sled needs to be provided (which may not be `/`).
+    fn from_url(url: &url::Url) -> Result<Self, Error> {
+        if url.scheme() != "sled" {
+            return Err(crate::Error::StorageError("invalid scheme".to_string()));
+        }
+
+        if url.has_host() {
+            return Err(crate::Error::StorageError(format!(
+                "invalid host: {}",
+                url.host().unwrap()
+            )));
+        }
+
+        // TODO: expose compression and other parameters as URL parameters, drop new and new_temporary?
+        if url.path().is_empty() {
+            Self::new_temporary().map_err(|e| Error::StorageError(e.to_string()))
+        } else {
+            if url.path() == "/" {
+                Err(crate::Error::StorageError(
+                    "cowardly refusing to open / with sled".to_string(),
+                ))
+            } else {
+                Self::new(url.path().into()).map_err(|e| Error::StorageError(e.to_string()))
+            }
+        }
+    }
+
     #[instrument(skip(self), fields(blob.digest=%digest))]
     fn has(&self, digest: &B3Digest) -> Result<bool, Error> {
         match self.db.contains_key(digest.to_vec()) {
@@ -127,3 +157,77 @@ impl BlobWriter for SledBlobWriter {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use tempfile::TempDir;
+
+    use super::BlobService;
+    use super::SledBlobService;
+
+    /// This uses a wrong scheme.
+    #[test]
+    fn test_invalid_scheme() {
+        let url = url::Url::parse("http://foo.example/test").expect("must parse");
+
+        assert!(SledBlobService::from_url(&url).is_err());
+    }
+
+    /// This uses the correct scheme, and doesn't specify a path (temporary sled).
+    #[test]
+    fn test_valid_scheme_temporary() {
+        let url = url::Url::parse("sled://").expect("must parse");
+
+        assert!(SledBlobService::from_url(&url).is_ok());
+    }
+
+    /// This sets the path to a location that doesn't exist, which should fail (as sled doesn't mkdir -p)
+    #[test]
+    fn test_nonexistent_path() {
+        let tmpdir = TempDir::new().unwrap();
+
+        let mut url = url::Url::parse("sled://foo.example").expect("must parse");
+        url.set_path(tmpdir.path().join("foo").join("bar").to_str().unwrap());
+
+        assert!(SledBlobService::from_url(&url).is_err());
+    }
+
+    /// This uses the correct scheme, and specifies / as path (which should fail
+    // for obvious reasons)
+    #[test]
+    fn test_invalid_path_root() {
+        let url = url::Url::parse("sled:///").expect("must parse");
+
+        assert!(SledBlobService::from_url(&url).is_err());
+    }
+
+    /// This uses the correct scheme, and sets a tempdir as location.
+    #[test]
+    fn test_valid_scheme_path() {
+        let tmpdir = TempDir::new().unwrap();
+
+        let mut url = url::Url::parse("sled://").expect("must parse");
+        url.set_path(tmpdir.path().to_str().unwrap());
+
+        assert!(SledBlobService::from_url(&url).is_ok());
+    }
+
+    /// This sets a host, rather than a path, which should fail.
+    #[test]
+    fn test_invalid_host() {
+        let url = url::Url::parse("sled://foo.example").expect("must parse");
+
+        assert!(SledBlobService::from_url(&url).is_err());
+    }
+
+    /// This sets a host AND a valid path, which should fail
+    #[test]
+    fn test_invalid_host_and_path() {
+        let tmpdir = TempDir::new().unwrap();
+
+        let mut url = url::Url::parse("sled://foo.example").expect("must parse");
+        url.set_path(tmpdir.path().to_str().unwrap());
+
+        assert!(SledBlobService::from_url(&url).is_err());
+    }
+}