Make the use_dualstack provider public (#3611)

Addresses awslabs/aws-sdk-rust#879

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Co-authored-by: ysaito1001 <awsaito@amazon.com>

CHANGELOG.next.toml

@@ -64,3 +64,9 @@ message = "Fix event stream `:content-type` message headers for struct messages.
 references = ["smithy-rs#3603"]
 meta = { "breaking" = false, "tada" = false, "bug" = true, "target" = "all" }
 author = "jdisanti"
+
+[[aws-sdk-rust]]
+message = "`aws_config::default_provider::use_dual_stack_provider` is now public instead of `pub(crate)`"
+references = ["aws-sdk-rust#879", "smithy-rs#3611"]
+meta = { "breaking" = false, "tada" = false, "bug" = false }
+author = "jdisanti"

aws/rust-runtime/aws-config/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "aws-config"
-version = "1.2.1"
+version = "1.3.0"
 authors = [
     "AWS Rust SDK Team <aws-sdk-rust@amazon.com>",
     "Russell Cohen <rcoh@amazon.com>",

aws/rust-runtime/aws-config/src/default_provider/use_dual_stack.rs

@@ -16,7 +16,14 @@ mod profile_key {
     pub(super) const USE_DUAL_STACK: &str = "use_dualstack_endpoint";
 }
 
-pub(crate) async fn use_dual_stack_provider(provider_config: &ProviderConfig) -> Option<bool> {
+/// Load the value for "use dual-stack"
+///
+/// This checks the following sources:
+/// 1. The environment variable `AWS_USE_DUALSTACK_ENDPOINT=true/false`
+/// 2. The profile key `use_dualstack_endpoint=true/false`
+///
+/// If invalid values are found, the provider will return `None` and an error will be logged.
+pub async fn use_dual_stack_provider(provider_config: &ProviderConfig) -> Option<bool> {
     let env = provider_config.env();
     let profiles = provider_config.profile().await;