feat(tvix/castore/directory): add bigtable backend

This adds a Directory service using
https://cloud.google.com/bigtable/docs/ as a K/V store.

Directory (closures) are put in individual keys.

We don't do any bucketed upload of directory closures (yet), as castore/
fs does query individually, does not request recursively (and buffers).
This will be addressed by store composition at some point.

Change-Id: I7fada45bf386a78b7ec93be38c5f03879a2a6e22
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11212
Tested-by: BuildkiteCI
Reviewed-by: Connor Brewster <cbrewster@hey.com>
Autosubmit: flokli <flokli@flokli.de>

tvix/castore/Cargo.toml

@@ -29,6 +29,15 @@ tracing = "0.1.37"
 url = "2.4.0"
 walkdir = "2.4.0"
 zstd = "0.13.0"
+serde = { version = "1.0.197", features = [ "derive" ] }
+serde_with = "3.7.0"
+serde_qs = "0.12.0"
+
+[dependencies.bigtable_rs]
+optional = true
+# https://github.com/liufuyang/bigtable_rs/pull/72
+git = "https://github.com/flokli/bigtable_rs"
+rev = "0af404741dfc40eb9fa99cf4d4140a09c5c20df7"
 
 [dependencies.fuse-backend-rs]
 optional = true
@@ -71,6 +80,7 @@ prost-build = "0.12.1"
 tonic-build = "0.11.0"
 
 [dev-dependencies]
+async-process = "2.1.0"
 rstest = "0.18.2"
 tempfile = "3.3.0"
 tokio-retry = "0.3.0"
@@ -80,6 +90,7 @@ rstest_reuse = "0.6.0"
 [features]
 default = []
 cloud = [
+  "dep:bigtable_rs",
   "object_store/aws",
   "object_store/azure",
   "object_store/gcp",

tvix/castore/default.nix

@@ -4,5 +4,9 @@ depot.tvix.crates.workspaceMembers.tvix-castore.build.override {
   runTests = true;
   testPreRun = ''
     export SSL_CERT_FILE=${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt;
+    export PATH="$PATH:${pkgs.lib.makeBinPath [pkgs.cbtemulator pkgs.google-cloud-bigtable-tool]}"
   '';
+
+  # enable some optional features.
+  features = [ "default" "cloud" ];
 }

tvix/castore/src/directoryservice/bigtable.rs

@@ -0,0 +1,355 @@
+use bigtable_rs::{bigtable, google::bigtable::v2 as bigtable_v2};
+use bytes::Bytes;
+use data_encoding::HEXLOWER;
+use futures::stream::BoxStream;
+use prost::Message;
+use serde::{Deserialize, Serialize};
+use serde_with::{serde_as, DurationSeconds};
+use tonic::async_trait;
+use tracing::{instrument, trace, warn};
+
+use super::{utils::traverse_directory, DirectoryPutter, DirectoryService, SimplePutter};
+use crate::{proto, B3Digest, Error};
+
+/// There should not be more than 10 MiB in a single cell.
+/// https://cloud.google.com/bigtable/docs/schema-design#cells
+const CELL_SIZE_LIMIT: u64 = 10 * 1024 * 1024;
+
+/// Provides a [DirectoryService] implementation using
+/// [Bigtable](https://cloud.google.com/bigtable/docs/)
+/// as an underlying K/V store.
+///
+/// # Data format
+/// We use Bigtable as a plain K/V store.
+/// The row key is the digest of the directory, in hexlower.
+/// Inside the row, we currently have a single column/cell, again using the
+/// hexlower directory digest.
+/// Its value is the Directory message, serialized in canonical protobuf.
+/// We currently only populate this column.
+///
+/// In the future, we might want to introduce "bucketing", essentially storing
+/// all directories inserted via `put_multiple_start` in a batched form.
+/// This will prevent looking up intermediate Directories, which are not
+/// directly at the root, so rely on store composition.
+#[derive(Clone)]
+pub struct BigtableDirectoryService {
+    client: bigtable::BigTable,
+    params: BigtableParameters,
+
+    #[cfg(test)]
+    #[allow(dead_code)]
+    /// Holds the temporary directory containing the unix socket, and the
+    /// spawned emulator process.
+    emulator: std::sync::Arc<(tempfile::TempDir, async_process::Child)>,
+}
+
+/// Represents configuration of [BigtableDirectoryService].
+/// This currently conflates both connect parameters and data model/client
+/// behaviour parameters.
+#[serde_as]
+#[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
+pub struct BigtableParameters {
+    project_id: String,
+    instance_name: String,
+    #[serde(default)]
+    is_read_only: bool,
+    #[serde(default = "default_channel_size")]
+    channel_size: usize,
+
+    #[serde_as(as = "Option<DurationSeconds<String>>")]
+    #[serde(default = "default_timeout")]
+    timeout: Option<std::time::Duration>,
+    table_name: String,
+    family_name: String,
+
+    #[serde(default = "default_app_profile_id")]
+    app_profile_id: String,
+}
+
+fn default_app_profile_id() -> String {
+    "default".to_owned()
+}
+
+fn default_channel_size() -> usize {
+    4
+}
+
+fn default_timeout() -> Option<std::time::Duration> {
+    Some(std::time::Duration::from_secs(4))
+}
+
+impl BigtableDirectoryService {
+    #[cfg(not(test))]
+    pub async fn connect(params: BigtableParameters) -> Result<Self, bigtable::Error> {
+        let connection = bigtable::BigTableConnection::new(
+            &params.project_id,
+            &params.instance_name,
+            params.is_read_only,
+            params.channel_size,
+            params.timeout,
+        )
+        .await?;
+
+        Ok(Self {
+            client: connection.client(),
+            params,
+        })
+    }
+
+    #[cfg(test)]
+    pub async fn connect(params: BigtableParameters) -> Result<Self, bigtable::Error> {
+        use std::time::Duration;
+
+        use async_process::{Command, Stdio};
+        use tempfile::TempDir;
+        use tokio_retry::{strategy::ExponentialBackoff, Retry};
+
+        let tmpdir = TempDir::new().unwrap();
+
+        let socket_path = tmpdir.path().join("cbtemulator.sock");
+
+        let emulator_process = Command::new("cbtemulator")
+            .arg("-address")
+            .arg(socket_path.clone())
+            .stderr(Stdio::piped())
+            .stdout(Stdio::piped())
+            .kill_on_drop(true)
+            .spawn()
+            .expect("failed to spwan emulator");
+
+        Retry::spawn(
+            ExponentialBackoff::from_millis(20).max_delay(Duration::from_secs(1)),
+            || async {
+                if socket_path.exists() {
+                    Ok(())
+                } else {
+                    Err(())
+                }
+            },
+        )
+        .await
+        .expect("failed to wait for socket");
+
+        // populate the emulator
+        for cmd in &[
+            vec!["createtable", &params.table_name],
+            vec!["createfamily", &params.table_name, &params.family_name],
+        ] {
+            Command::new("cbt")
+                .args({
+                    let mut args = vec![
+                        "-instance",
+                        &params.instance_name,
+                        "-project",
+                        &params.project_id,
+                    ];
+                    args.extend_from_slice(cmd);
+                    args
+                })
+                .env(
+                    "BIGTABLE_EMULATOR_HOST",
+                    format!("unix://{}", socket_path.to_string_lossy()),
+                )
+                .output()
+                .await
+                .expect("failed to run cbt setup command");
+        }
+
+        let connection = bigtable_rs::bigtable::BigTableConnection::new_with_emulator(
+            &format!("unix://{}", socket_path.to_string_lossy()),
+            &params.project_id,
+            &params.instance_name,
+            params.is_read_only,
+            params.timeout,
+        )?;
+
+        Ok(Self {
+            client: connection.client(),
+            params,
+            emulator: (tmpdir, emulator_process).into(),
+        })
+    }
+}
+
+/// Derives the row/column key for a given blake3 digest.
+/// We use hexlower encoding, also because it can't be misinterpreted as RE2.
+fn derive_directory_key(digest: &B3Digest) -> String {
+    HEXLOWER.encode(digest.as_slice())
+}
+
+#[async_trait]
+impl DirectoryService for BigtableDirectoryService {
+    #[instrument(skip(self, digest), err, fields(directory.digest = %digest))]
+    async fn get(&self, digest: &B3Digest) -> Result<Option<proto::Directory>, Error> {
+        let mut client = self.client.clone();
+        let directory_key = derive_directory_key(digest);
+
+        let request = bigtable_v2::ReadRowsRequest {
+            app_profile_id: self.params.app_profile_id.to_string(),
+            table_name: client.get_full_table_name(&self.params.table_name),
+            rows_limit: 1,
+            rows: Some(bigtable_v2::RowSet {
+                row_keys: vec![directory_key.clone().into()],
+                row_ranges: vec![],
+            }),
+            // Filter selected family name, and column qualifier matching our digest.
+            // This is to ensure we don't fail once we start bucketing.
+            filter: Some(bigtable_v2::RowFilter {
+                filter: Some(bigtable_v2::row_filter::Filter::Chain(
+                    bigtable_v2::row_filter::Chain {
+                        filters: vec![
+                            bigtable_v2::RowFilter {
+                                filter: Some(
+                                    bigtable_v2::row_filter::Filter::FamilyNameRegexFilter(
+                                        self.params.family_name.to_string(),
+                                    ),
+                                ),
+                            },
+                            bigtable_v2::RowFilter {
+                                filter: Some(
+                                    bigtable_v2::row_filter::Filter::ColumnQualifierRegexFilter(
+                                        directory_key.clone().into(),
+                                    ),
+                                ),
+                            },
+                        ],
+                    },
+                )),
+            }),
+            ..Default::default()
+        };
+
+        let mut response = client
+            .read_rows(request)
+            .await
+            .map_err(|e| Error::StorageError(format!("unable to read rows: {}", e)))?;
+
+        if response.len() != 1 {
+            if response.len() > 1 {
+                // This shouldn't happen, we limit number of rows to 1
+                return Err(Error::StorageError(
+                    "got more than one row from bigtable".into(),
+                ));
+            }
+            // else, this is simply a "not found".
+            return Ok(None);
+        }
+
+        let (row_key, mut row_cells) = response.pop().unwrap();
+        if row_key != directory_key.as_bytes() {
+            // This shouldn't happen, we requested this row key.
+            return Err(Error::StorageError(
+                "got wrong row key from bigtable".into(),
+            ));
+        }
+
+        let row_cell = row_cells
+            .pop()
+            .ok_or_else(|| Error::StorageError("found no cells".into()))?;
+
+        // Ensure there's only one cell (so no more left after the pop())
+        // This shouldn't happen, We filter out other cells in our query.
+        if !row_cells.is_empty() {
+            return Err(Error::StorageError(
+                "more than one cell returned from bigtable".into(),
+            ));
+        }
+
+        // We also require the qualifier to be correct in the filter above,
+        // so this shouldn't happen.
+        if directory_key.as_bytes() != row_cell.qualifier {
+            return Err(Error::StorageError("unexpected cell qualifier".into()));
+        }
+
+        // For the data in that cell, ensure the digest matches what's requested, before parsing.
+        let got_digest = B3Digest::from(blake3::hash(&row_cell.value).as_bytes());
+        if got_digest != *digest {
+            return Err(Error::StorageError(format!(
+                "invalid digest: {}",
+                got_digest
+            )));
+        }
+
+        // Try to parse the value into a Directory message.
+        let directory = proto::Directory::decode(Bytes::from(row_cell.value))
+            .map_err(|e| Error::StorageError(format!("unable to decode directory proto: {}", e)))?;
+
+        // validate the Directory.
+        directory
+            .validate()
+            .map_err(|e| Error::StorageError(format!("invalid Directory message: {}", e)))?;
+
+        Ok(Some(directory))
+    }
+
+    #[instrument(skip(self, directory), err, fields(directory.digest = %directory.digest()))]
+    async fn put(&self, directory: proto::Directory) -> Result<B3Digest, Error> {
+        let directory_digest = directory.digest();
+        let mut client = self.client.clone();
+        let directory_key = derive_directory_key(&directory_digest);
+
+        // Ensure the directory we're trying to upload passes validation
+        directory
+            .validate()
+            .map_err(|e| Error::InvalidRequest(format!("directory is invalid: {}", e)))?;
+
+        let data = directory.encode_to_vec();
+        if data.len() as u64 > CELL_SIZE_LIMIT {
+            return Err(Error::StorageError(
+                "Directory exceeds cell limit on Bigtable".into(),
+            ));
+        }
+
+        let resp = client
+            .check_and_mutate_row(bigtable_v2::CheckAndMutateRowRequest {
+                table_name: client.get_full_table_name(&self.params.table_name),
+                app_profile_id: self.params.app_profile_id.to_string(),
+                row_key: directory_key.clone().into(),
+                predicate_filter: Some(bigtable_v2::RowFilter {
+                    filter: Some(bigtable_v2::row_filter::Filter::ColumnQualifierRegexFilter(
+                        directory_key.clone().into(),
+                    )),
+                }),
+                // If the column was already found, do nothing.
+                true_mutations: vec![],
+                // Else, do the insert.
+                false_mutations: vec![
+                    // https://cloud.google.com/bigtable/docs/writes
+                    bigtable_v2::Mutation {
+                        mutation: Some(bigtable_v2::mutation::Mutation::SetCell(
+                            bigtable_v2::mutation::SetCell {
+                                family_name: self.params.family_name.to_string(),
+                                column_qualifier: directory_key.clone().into(),
+                                timestamp_micros: -1, // use server time to fill timestamp
+                                value: data,
+                            },
+                        )),
+                    },
+                ],
+            })
+            .await
+            .map_err(|e| Error::StorageError(format!("unable to mutate rows: {}", e)))?;
+
+        if resp.predicate_matched {
+            trace!("already existed")
+        }
+
+        Ok(directory_digest)
+    }
+
+    #[instrument(skip_all, fields(directory.digest = %root_directory_digest))]
+    fn get_recursive(
+        &self,
+        root_directory_digest: &B3Digest,
+    ) -> BoxStream<Result<proto::Directory, Error>> {
+        traverse_directory(self.clone(), root_directory_digest)
+    }
+
+    #[instrument(skip_all)]
+    fn put_multiple_start(&self) -> Box<(dyn DirectoryPutter + 'static)>
+    where
+        Self: Clone,
+    {
+        Box::new(SimplePutter::new(self.clone()))
+    }
+}

tvix/castore/src/directoryservice/from_addr.rs

@@ -19,7 +19,8 @@ use super::{DirectoryService, GRPCDirectoryService, MemoryDirectoryService, Sled
 /// - `grpc+http://host:port`, `grpc+https://host:port`
 ///    Connects to a (remote) tvix-store gRPC service.
 pub async fn from_addr(uri: &str) -> Result<Box<dyn DirectoryService>, crate::Error> {
-    let url = Url::parse(uri)
+    #[allow(unused_mut)]
+    let mut url = Url::parse(uri)
         .map_err(|e| crate::Error::StorageError(format!("unable to parse url: {}", e)))?;
 
     let directory_service: Box<dyn DirectoryService> = match url.scheme() {
@@ -62,6 +63,30 @@ pub async fn from_addr(uri: &str) -> Result<Box<dyn DirectoryService>, crate::Er
             let client = DirectoryServiceClient::new(crate::tonic::channel_from_url(&url).await?);
             Box::new(GRPCDirectoryService::from_client(client))
         }
+        #[cfg(feature = "cloud")]
+        "bigtable" => {
+            use super::bigtable::BigtableParameters;
+            use super::BigtableDirectoryService;
+
+            // parse the instance name from the hostname.
+            let instance_name = url
+                .host_str()
+                .ok_or_else(|| Error::StorageError("instance name missing".into()))?
+                .to_string();
+
+            // … but add it to the query string now, so we just need to parse that.
+            url.query_pairs_mut()
+                .append_pair("instance_name", &instance_name);
+
+            let params: BigtableParameters = serde_qs::from_str(url.query().unwrap_or_default())
+                .map_err(|e| Error::InvalidRequest(format!("failed to parse parameters: {}", e)))?;
+
+            Box::new(
+                BigtableDirectoryService::connect(params)
+                    .await
+                    .map_err(|e| Error::StorageError(e.to_string()))?,
+            )
+        }
         _ => {
             return Err(crate::Error::StorageError(format!(
                 "unknown scheme: {}",
@@ -117,6 +142,27 @@ mod tests {
     #[case::grpc_valid_https_host_without_port("grpc+https://localhost", true)]
     /// Correct scheme to connect to localhost over http, but with additional path, which is invalid.
     #[case::grpc_invalid_host_and_path("grpc+http://localhost/some-path", false)]
+    /// A valid example for Bigtable
+    #[cfg_attr(
+        feature = "cloud",
+        case::bigtable_valid_url(
+            "bigtable://instance-1?project_id=project-1&table_name=table-1&family_name=cf1",
+            true
+        )
+    )]
+    /// A valid example for Bigtable, specifying a custom channel size and timeout
+    #[cfg_attr(
+        feature = "cloud",
+        case::bigtable_valid_url(
+            "bigtable://instance-1?project_id=project-1&table_name=table-1&family_name=cf1&channel_size=10&timeout=10",
+            true
+        )
+    )]
+    /// A invalid Bigtable example (missing fields)
+    #[cfg_attr(
+        feature = "cloud",
+        case::bigtable_invalid_url("bigtable://instance-1", false)
+    )]
     #[tokio::test]
     async fn test_from_addr_tokio(#[case] uri_str: &str, #[case] exp_succeed: bool) {
         if exp_succeed {

tvix/castore/src/directoryservice/mod.rs

@@ -22,6 +22,12 @@ pub use self::sled::SledDirectoryService;
 pub use self::traverse::descend_to;
 pub use self::utils::traverse_directory;
 
+#[cfg(feature = "cloud")]
+mod bigtable;
+
+#[cfg(feature = "cloud")]
+pub use self::bigtable::BigtableDirectoryService;
+
 /// The base trait all Directory services need to implement.
 /// This is a simple get and put of [crate::proto::Directory], returning their
 /// digest.

tvix/castore/src/directoryservice/tests/mod.rs

@@ -26,6 +26,7 @@ use self::utils::make_grpc_directory_service_client;
 #[case::grpc(make_grpc_directory_service_client().await)]
 #[case::memory(directoryservice::from_addr("memory://").await.unwrap())]
 #[case::sled(directoryservice::from_addr("sled://").await.unwrap())]
+#[cfg_attr(feature = "cloud", case::bigtable(directoryservice::from_addr("bigtable://instance-1?project_id=project-1&table_name=table-1&family_name=cf1").await.unwrap()))]
 pub fn directory_services(#[case] directory_service: impl DirectoryService) {}
 
 /// Ensures asking for a directory that doesn't exist returns a Ok(None).

tvix/castore/src/directoryservice/tests/utils.rs

@@ -5,6 +5,7 @@ use crate::{
     directoryservice::MemoryDirectoryService,
     proto::directory_service_server::DirectoryServiceServer,
 };
+
 use tonic::transport::{Endpoint, Server, Uri};
 
 /// Constructs and returns a gRPC DirectoryService.