Add S3 http2 toggle flag

nativelink-config/src/stores.rs

@@ -480,6 +480,16 @@ pub struct S3Store {
     /// Default: false
     #[serde(default)]
     pub insecure_allow_http: bool,
+
+    /// Disable http/2 connections and only use http/1.1. Default client
+    /// configuration will have http/1.1 and http/2 enabled for connection
+    /// schemes. Http/2 should be disabled if environments have poor support
+    /// or performance related to http/2. Safe to keep default unless
+    /// underlying network environment or S3 API servers specify otherwise.
+    ///
+    /// Default: false
+    #[serde(default)]
+    pub disable_http2: bool,
 }
 
 #[allow(non_camel_case_types)]

nativelink-store/src/s3_store.rs

@@ -82,7 +82,11 @@ impl TlsConnector {
             connector_with_roots.https_only()
         };
 
-        let connector = connector_with_schemes.enable_http1().enable_http2().build();
+        let connector = if config.disable_http2 {
+            connector_with_schemes.enable_http1().build()
+        } else {
+            connector_with_schemes.enable_http1().enable_http2().build()
+        };
 
         Self {
             connector,