Support native S3 conditional writes

Add support for `PutMode::Create` and `copy_if_not_exists` on native AWS
S3, which uses the underlying conditional write primitive that Amazon
launched earlier this year [0].

The conditional write primitive is simpler than what's available in
other S3-like products (e.g., R2), so new modes for
`s3_copy_if_not_exists` and `s3_conditional_put` are added to select the
native S3-specific behavior.

To maintain strict backwards compatibility (e.g. with older versions of
LocalStack), the new behavior is not on by default. It must be
explicitly requested by the end user.

The implementation for `PutMode::Create` is straightforward. The
implementation of `copy_if_not_exists` is a bit more involved, as it
requires managing a multipart upload that uses the UploadPartCopy
operation, which was not previously supported by this crate's S3 client.

To ensure test coverage, the object store workflow now runs the AWS
integration tests with conditional put both disabled and enabled.

Fix apache#6285.

[0]: https://aws.amazon.com/about-aws/whats-new/2024/08/amazon-s3-conditional-writes/

.github/workflows/object_store.yml

@@ -161,6 +161,12 @@ jobs:
       - name: Run object_store tests
         run: cargo test --features=aws,azure,gcp,http
 
+      - name: Run object_store tests (AWS native conditional put)
+        run: cargo test --features=aws
+        env:
+          AWS_CONDITIONAL_PUT: etag-create-only
+          AWS_COPY_IF_NOT_EXISTS: multipart
+
       - name: GCS Output
         if: ${{ !cancelled() }}
         run: docker logs $GCS_CONTAINER

object_store/src/aws/client.rs

@@ -28,8 +28,8 @@ use crate::client::header::{get_put_result, get_version};
 use crate::client::list::ListClient;
 use crate::client::retry::RetryExt;
 use crate::client::s3::{
-    CompleteMultipartUpload, CompleteMultipartUploadResult, InitiateMultipartUploadResult,
-    ListResponse,
+    CompleteMultipartUpload, CompleteMultipartUploadResult, CopyPartResult,
+    InitiateMultipartUploadResult, ListResponse,
 };
 use crate::client::GetOptionsExt;
 use crate::multipart::PartId;
@@ -98,8 +98,11 @@ pub(crate) enum Error {
     #[snafu(display("Error getting create multipart response body: {}", source))]
     CreateMultipartResponseBody { source: reqwest::Error },
 
-    #[snafu(display("Error performing complete multipart request: {}", source))]
-    CompleteMultipartRequest { source: crate::client::retry::Error },
+    #[snafu(display("Error performing complete multipart request: {}: {}", path, source))]
+    CompleteMultipartRequest {
+        source: crate::client::retry::Error,
+        path: String,
+    },
 
     #[snafu(display("Error getting complete multipart response body: {}", source))]
     CompleteMultipartResponseBody { source: reqwest::Error },
@@ -118,13 +121,32 @@ pub(crate) enum Error {
 
 impl From<Error> for crate::Error {
     fn from(err: Error) -> Self {
-        Self::Generic {
-            store: STORE,
-            source: Box::new(err),
+        match err {
+            Error::CompleteMultipartRequest { source, path } => source.error(STORE, path),
+            _ => Self::Generic {
+                store: STORE,
+                source: Box::new(err),
+            },
         }
     }
 }
 
+pub(crate) enum PutPartPayload<'a> {
+    Part(PutPayload),
+    Copy(&'a Path),
+}
+
+impl Default for PutPartPayload<'_> {
+    fn default() -> Self {
+        Self::Part(PutPayload::default())
+    }
+}
+
+pub(crate) enum CompleteMultipartMode {
+    Overwrite,
+    Create,
+}
+
 #[derive(Deserialize)]
 #[serde(rename_all = "PascalCase", rename = "DeleteResult")]
 struct BatchDeleteResponse {
@@ -605,15 +627,24 @@ impl S3Client {
         path: &Path,
         upload_id: &MultipartId,
         part_idx: usize,
-        data: PutPayload,
+        data: PutPartPayload<'_>,
     ) -> Result<PartId> {
+        let is_copy = matches!(data, PutPartPayload::Copy(_));
         let part = (part_idx + 1).to_string();
 
         let mut request = self
             .request(Method::PUT, path)
-            .with_payload(data)
             .query(&[("partNumber", &part), ("uploadId", upload_id)])
             .idempotent(true);
+
+        request = match data {
+            PutPartPayload::Part(payload) => request.with_payload(payload),
+            PutPartPayload::Copy(path) => request.header(
+                "x-amz-copy-source",
+                &format!("{}/{}", self.config.bucket, path),
+            ),
+        };
+
         if self
             .config
             .encryption_headers
@@ -625,7 +656,18 @@ impl S3Client {
         }
         let response = request.send().await?;
 
-        let content_id = get_etag(response.headers()).context(MetadataSnafu)?;
+        let content_id = match is_copy {
+            false => get_etag(response.headers()).context(MetadataSnafu)?,
+            true => {
+                let response = response
+                    .bytes()
+                    .await
+                    .context(CreateMultipartResponseBodySnafu)?;
+                let response: CopyPartResult = quick_xml::de::from_reader(response.reader())
+                    .context(InvalidMultipartResponseSnafu)?;
+                response.e_tag
+            }
+        };
         Ok(PartId { content_id })
     }
 
@@ -634,12 +676,18 @@ impl S3Client {
         location: &Path,
         upload_id: &str,
         parts: Vec<PartId>,
+        mode: CompleteMultipartMode,
     ) -> Result<PutResult> {
         let parts = if parts.is_empty() {
             // If no parts were uploaded, upload an empty part
             // otherwise the completion request will fail
             let part = self
-                .put_part(location, &upload_id.to_string(), 0, PutPayload::default())
+                .put_part(
+                    location,
+                    &upload_id.to_string(),
+                    0,
+                    PutPartPayload::default(),
+                )
                 .await?;
             vec![part]
         } else {
@@ -651,18 +699,27 @@ impl S3Client {
         let credential = self.config.get_session_credential().await?;
         let url = self.config.path_url(location);
 
-        let response = self
+        let request = self
             .client
             .request(Method::POST, url)
             .query(&[("uploadId", upload_id)])
             .body(body)
-            .with_aws_sigv4(credential.authorizer(), None)
+            .with_aws_sigv4(credential.authorizer(), None);
+
+        let request = match mode {
+            CompleteMultipartMode::Overwrite => request,
+            CompleteMultipartMode::Create => request.header("If-None-Match", "*"),
+        };
+
+        let response = request
             .retryable(&self.config.retry_config)
             .idempotent(true)
             .retry_error_body(true)
             .send()
             .await
-            .context(CompleteMultipartRequestSnafu)?;
+            .context(CompleteMultipartRequestSnafu {
+                path: location.as_ref(),
+            })?;
 
         let version = get_version(response.headers(), VERSION_HEADER).context(MetadataSnafu)?;
 

object_store/src/aws/mod.rs

@@ -36,7 +36,7 @@ use reqwest::{Method, StatusCode};
 use std::{sync::Arc, time::Duration};
 use url::Url;
 
-use crate::aws::client::{RequestError, S3Client};
+use crate::aws::client::{CompleteMultipartMode, PutPartPayload, RequestError, S3Client};
 use crate::client::get::GetClientExt;
 use crate::client::list::ListClientExt;
 use crate::client::CredentialProvider;
@@ -169,7 +169,10 @@ impl ObjectStore for AmazonS3 {
         match (opts.mode, &self.client.config.conditional_put) {
             (PutMode::Overwrite, _) => request.idempotent(true).do_put().await,
             (PutMode::Create | PutMode::Update(_), None) => Err(Error::NotImplemented),
-            (PutMode::Create, Some(S3ConditionalPut::ETagMatch)) => {
+            (
+                PutMode::Create,
+                Some(S3ConditionalPut::ETagMatch | S3ConditionalPut::ETagCreateOnly),
+            ) => {
                 match request.header(&IF_NONE_MATCH, "*").do_put().await {
                     // Technically If-None-Match should return NotModified but some stores,
                     // such as R2, instead return PreconditionFailed
@@ -193,6 +196,7 @@ impl ObjectStore for AmazonS3 {
                     source: "ETag required for conditional put".to_string().into(),
                 })?;
                 match put {
+                    S3ConditionalPut::ETagCreateOnly => Err(Error::NotImplemented),
                     S3ConditionalPut::ETagMatch => {
                         request.header(&IF_MATCH, etag.as_str()).do_put().await
                     }
@@ -293,6 +297,34 @@ impl ObjectStore for AmazonS3 {
         let (k, v, status) = match &self.client.config.copy_if_not_exists {
             Some(S3CopyIfNotExists::Header(k, v)) => (k, v, StatusCode::PRECONDITION_FAILED),
             Some(S3CopyIfNotExists::HeaderWithStatus(k, v, status)) => (k, v, *status),
+            Some(S3CopyIfNotExists::Multipart) => {
+                let upload_id = self
+                    .client
+                    .create_multipart(to, PutMultipartOpts::default())
+                    .await?;
+                let part_id = self
+                    .client
+                    .put_part(to, &upload_id, 0, PutPartPayload::Copy(from))
+                    .await?;
+                let res = match self
+                    .client
+                    .complete_multipart(
+                        to,
+                        &upload_id,
+                        vec![part_id],
+                        CompleteMultipartMode::Create,
+                    )
+                    .await
+                {
+                    Err(e @ Error::Precondition { .. }) => Err(Error::AlreadyExists {
+                        path: to.to_string(),
+                        source: Box::new(e),
+                    }),
+                    Ok(_) => Ok(()),
+                    Err(e) => Err(e.into()),
+                };
+                return res;
+            }
             Some(S3CopyIfNotExists::Dynamo(lock)) => {
                 return lock.copy_if_not_exists(&self.client, from, to).await
             }
@@ -340,7 +372,12 @@ impl MultipartUpload for S3MultiPartUpload {
         Box::pin(async move {
             let part = state
                 .client
-                .put_part(&state.location, &state.upload_id, idx, data)
+                .put_part(
+                    &state.location,
+                    &state.upload_id,
+                    idx,
+                    PutPartPayload::Part(data),
+                )
                 .await?;
             state.parts.put(idx, part);
             Ok(())
@@ -352,7 +389,12 @@ impl MultipartUpload for S3MultiPartUpload {
 
         self.state
             .client
-            .complete_multipart(&self.state.location, &self.state.upload_id, parts)
+            .complete_multipart(
+                &self.state.location,
+                &self.state.upload_id,
+                parts,
+                CompleteMultipartMode::Overwrite,
+            )
             .await
     }
 
@@ -384,7 +426,9 @@ impl MultipartStore for AmazonS3 {
         part_idx: usize,
         data: PutPayload,
     ) -> Result<PartId> {
-        self.client.put_part(path, id, part_idx, data).await
+        self.client
+            .put_part(path, id, part_idx, PutPartPayload::Part(data))
+            .await
     }
 
     async fn complete_multipart(
@@ -393,7 +437,9 @@ impl MultipartStore for AmazonS3 {
         id: &MultipartId,
         parts: Vec<PartId>,
     ) -> Result<PutResult> {
-        self.client.complete_multipart(path, id, parts).await
+        self.client
+            .complete_multipart(path, id, parts, CompleteMultipartMode::Overwrite)
+            .await
     }
 
     async fn abort_multipart(&self, path: &Path, id: &MultipartId) -> Result<()> {
@@ -427,7 +473,6 @@ mod tests {
         let integration = config.build().unwrap();
         let config = &integration.client.config;
         let test_not_exists = config.copy_if_not_exists.is_some();
-        let test_conditional_put = config.conditional_put.is_some();
 
         put_get_delete_list(&integration).await;
         get_opts(&integration).await;
@@ -458,8 +503,9 @@ mod tests {
         if test_not_exists {
             copy_if_not_exists(&integration).await;
         }
-        if test_conditional_put {
-            put_opts(&integration, true).await;
+        if let Some(conditional_put) = &config.conditional_put {
+            let supports_update = !matches!(conditional_put, S3ConditionalPut::ETagCreateOnly);
+            put_opts(&integration, supports_update).await;
         }
 
         // run integration test with unsigned payload enabled

object_store/src/aws/precondition.rs

@@ -46,6 +46,15 @@ pub enum S3CopyIfNotExists {
     ///
     /// Encoded as `header-with-status:<HEADER_NAME>:<HEADER_VALUE>:<STATUS>` ignoring whitespace
     HeaderWithStatus(String, String, reqwest::StatusCode),
+    /// Native Amazon S3 supports copy if not exists through a multipart upload
+    /// where the upload copies an existing object and is completed only if
+    /// the new object does not already exist.
+    ///
+    /// WARNING: When using this mode, `copy_if_not_exists` does not copy
+    /// tags or attributes from the source object.
+    ///
+    /// Encoded as `multipart` ignoring whitespace.
+    Multipart,
     /// The name of a DynamoDB table to use for coordination
     ///
     /// Encoded as either `dynamo:<TABLE_NAME>` or `dynamo:<TABLE_NAME>:<TIMEOUT_MILLIS>`
@@ -64,13 +73,19 @@ impl std::fmt::Display for S3CopyIfNotExists {
             Self::HeaderWithStatus(k, v, code) => {
                 write!(f, "header-with-status: {k}: {v}: {}", code.as_u16())
             }
+            Self::Multipart => f.write_str("multipart"),
             Self::Dynamo(lock) => write!(f, "dynamo: {}", lock.table_name()),
         }
     }
 }
 
 impl S3CopyIfNotExists {
     fn from_str(s: &str) -> Option<Self> {
+        match s.trim() {
+            "multipart" => return Some(Self::Multipart),
+            _ => (),
+        };
+
         let (variant, value) = s.split_once(':')?;
         match variant.trim() {
             "header" => {
@@ -118,6 +133,17 @@ pub enum S3ConditionalPut {
     /// [HTTP precondition]: https://datatracker.ietf.org/doc/html/rfc9110#name-preconditions
     ETagMatch,
 
+    /// Like `ETagMatch`, but with support for `PutMode::Create` and not
+    /// `PutMode::Option`.
+    ///
+    /// This is the limited form of conditional put supported by Amazon S3
+    /// as of August 2024 ([announcement]).
+    ///
+    /// Encoded as `etag-create-only` ignoring whitespace.
+    ///
+    /// [announcement]: https://aws.amazon.com/about-aws/whats-new/2024/08/amazon-s3-conditional-writes/
+    ETagCreateOnly,
+
     /// The name of a DynamoDB table to use for coordination
     ///
     /// Encoded as either `dynamo:<TABLE_NAME>` or `dynamo:<TABLE_NAME>:<TIMEOUT_MILLIS>`
@@ -133,6 +159,7 @@ impl std::fmt::Display for S3ConditionalPut {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
             Self::ETagMatch => write!(f, "etag"),
+            Self::ETagCreateOnly => write!(f, "etag-create-only"),
             Self::Dynamo(lock) => write!(f, "dynamo: {}", lock.table_name()),
         }
     }
@@ -142,6 +169,7 @@ impl S3ConditionalPut {
     fn from_str(s: &str) -> Option<Self> {
         match s.trim() {
             "etag" => Some(Self::ETagMatch),
+            "etag-create-only" => Some(Self::ETagCreateOnly),
             trimmed => match trimmed.split_once(':')? {
                 ("dynamo", s) => Some(Self::Dynamo(DynamoCommit::from_str(s)?)),
                 _ => None,

object_store/src/client/s3.rs

@@ -92,6 +92,13 @@ pub(crate) struct InitiateMultipartUploadResult {
     pub upload_id: String,
 }
 
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "PascalCase")]
+pub(crate) struct CopyPartResult {
+    #[serde(rename = "ETag")]
+    pub e_tag: String,
+}
+
 #[derive(Debug, Serialize)]
 #[serde(rename_all = "PascalCase")]
 pub(crate) struct CompleteMultipartUpload {