feat(tvix/store/directorysvc): add from_addr

Add --directory-service-addr arg to tvix-store CLI.

Change-Id: Iea1e6f08f27f7157b21ccf397297c68358bd78a0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8743
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: tazjin <tazjin@tvl.su>

tvix/store/src/directoryservice/grpc.rs

@@ -3,6 +3,7 @@ use std::collections::HashSet;
 use super::{DirectoryPutter, DirectoryService};
 use crate::proto::{self, get_directory_request::ByWhat};
 use crate::{B3Digest, Error};
+use tokio::net::UnixStream;
 use tokio::sync::mpsc::UnboundedSender;
 use tokio_stream::wrappers::UnboundedReceiverStream;
 use tonic::{transport::Channel, Status};
@@ -21,7 +22,7 @@ pub struct GRPCDirectoryService {
 }
 
 impl GRPCDirectoryService {
-    /// construct a [GRPCDirectoryService] from a [proto::blob_service_client::BlobServiceClient<Channel>].
+    /// construct a [GRPCDirectoryService] from a [proto::directory_service_client::DirectoryServiceClient<Channel>].
     /// panics if called outside the context of a tokio runtime.
     pub fn from_client(
         grpc_client: proto::directory_service_client::DirectoryServiceClient<Channel>,
@@ -34,6 +35,59 @@ impl GRPCDirectoryService {
 }
 
 impl DirectoryService for GRPCDirectoryService {
+    /// Constructs a [GRPCDirectoryService] 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::directory_service_client::DirectoryServiceClient::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::directory_service_client::DirectoryServiceClient::new(channel);
+                    Ok(Self::from_client(grpc_client))
+                }
+            }
+        }
+    }
     fn get(&self, digest: &B3Digest) -> Result<Option<crate::proto::Directory>, crate::Error> {
         // Get a new handle to the gRPC client, and copy the digest.
         let mut grpc_client = self.grpc_client.clone();