feat: expose opendal S3 options for anonymous access (#757)

Author: gruuya

crates/iceberg/src/io/storage_s3.rs

@@ -58,6 +58,11 @@ pub const S3_ASSUME_ROLE_ARN: &str = "client.assume-role.arn";
 pub const S3_ASSUME_ROLE_EXTERNAL_ID: &str = "client.assume-role.external-id";
 /// Optional session name used to assume an IAM role.
 pub const S3_ASSUME_ROLE_SESSION_NAME: &str = "client.assume-role.session-name";
+/// Option to skip signing request (e.g. for public buckets/folders)
+pub const S3_ALLOW_ANONYMOUS: &str = "s3.allow-anonymous";
+/// Option to skip loading the credential from EC2 metadata (typically used in conjunction with
+/// `S3_ALLOW_ANONYMOUS`)
+pub const S3_DISABLE_EC2_METADATA: &str = "s3.disable-ec2-metadata";
 
 /// Parse iceberg props to s3 config.
 pub(crate) fn s3_config_parse(mut m: HashMap<String, String>) -> Result<S3Config> {
@@ -81,7 +86,7 @@ pub(crate) fn s3_config_parse(mut m: HashMap<String, String>) -> Result<S3Config
         cfg.region = Some(region);
     };
     if let Some(path_style_access) = m.remove(S3_PATH_STYLE_ACCESS) {
-        if ["true", "True", "1"].contains(&path_style_access.as_str()) {
+        if ["true", "t", "1"].contains(&path_style_access.to_lowercase().as_str()) {
             cfg.enable_virtual_host_style = true;
         }
     };
@@ -126,6 +131,17 @@ pub(crate) fn s3_config_parse(mut m: HashMap<String, String>) -> Result<S3Config
         }
     };
 
+    if let Some(allow_anonymous) = m.remove(S3_ALLOW_ANONYMOUS) {
+        if ["true", "t", "1", "on"].contains(&allow_anonymous.to_lowercase().as_str()) {
+            cfg.allow_anonymous = true;
+        }
+    }
+    if let Some(disable_ec2_metadata) = m.remove(S3_DISABLE_EC2_METADATA) {
+        if ["true", "t", "1", "on"].contains(&disable_ec2_metadata.to_lowercase().as_str()) {
+            cfg.disable_ec2_metadata = true;
+        }
+    };
+
     Ok(cfg)
 }