feat: add reqwest ClientBuilder parameter to schema registry builder

This change enables the ability to add any arbitrary change to the HTTP
client used by the registry client. Therein, we get the chance to add
TLS and more notably mTLS support (even with whichever chain we wish,
such as rustls).

This change is required as we wish to use a registry protected with
mTLS, and will therefore need special configuration from reqwest.

Signed-off-by: Mariell Hoversholm <[email protected]>

src/async_impl/schema_registry.rs

@@ -9,7 +9,7 @@ use futures::future::{BoxFuture, FutureExt};
 use futures::stream::{self, StreamExt};
 use reqwest::header;
 use reqwest::header::{HeaderName, ACCEPT, CONTENT_TYPE};
-use reqwest::Client;
+use reqwest::{Client, ClientBuilder};
 use serde_json::{json, Map, Value};
 
 use crate::error::SRCError;
@@ -130,8 +130,33 @@ impl SrSettingsBuilder {
         self
     }
 
+    /// Build the settings with your own HTTP client.
+    ///
+    /// This method allows you to bring your own TLS client and configuration.
+    ///
+    /// NOTE: The other values (headers, proxy, etc.) will still be merged in
+    /// and they all have higher precedence than your own builder's configuration.
+    /// This means that if you set a proxy both with this builde rand your
+    /// client's builder, this builder will overwrite the client's builder.
+    pub fn build_with(&mut self, builder: ClientBuilder) -> Result<SrSettings, SRCError> {
+        let client = self.build_client(builder)?;
+        let urls = self.urls.clone();
+        let authorization = self.authorization.clone();
+        Ok(SrSettings {
+            urls,
+            client,
+            authorization,
+        })
+    }
+
+    /// Build the settings.
+    ///
+    /// If you need your own client, see `build_with`.
     pub fn build(&mut self) -> Result<SrSettings, SRCError> {
-        let mut builder = Client::builder();
+        self.build_with(Client::builder())
+    }
+
+    fn build_client(&mut self, mut builder: ClientBuilder) -> Result<Client, SRCError> {
         if !self.headers.is_empty() {
             let mut header_map = header::HeaderMap::new();
             for (k, v) in self.headers.iter() {
@@ -155,18 +180,14 @@ impl SrSettingsBuilder {
             };
         }
         builder = builder.timeout(self.timeout);
-        let urls = self.urls.clone();
-        let authorization = self.authorization.clone();
         match builder.build() {
-            Ok(client) => Ok(SrSettings {
-                urls,
-                client,
-                authorization,
-            }),
-            Err(e) => Err(SRCError::non_retryable_with_cause(
-                e,
-                "could not create new client",
-            )),
+            Ok(client) => Ok(client),
+            Err(e) => {
+                return Err(SRCError::non_retryable_with_cause(
+                    e,
+                    "could not create new client",
+                ))
+            }
         }
     }
 }

src/blocking/schema_registry.rs

@@ -5,7 +5,7 @@ use std::collections::HashMap;
 use std::str;
 use std::time::Duration;
 
-use reqwest::blocking::Client;
+use reqwest::blocking::{Client, ClientBuilder};
 use reqwest::header;
 use reqwest::header::{HeaderName, ACCEPT, CONTENT_TYPE};
 use serde_json::{json, Map, Value};
@@ -128,8 +128,33 @@ impl SrSettingsBuilder {
         self
     }
 
+    /// Build the settings with your own HTTP client.
+    ///
+    /// This method allows you to bring your own TLS client and configuration.
+    ///
+    /// NOTE: The other values (headers, proxy, etc.) will still be merged in
+    /// and they all have higher precedence than your own builder's configuration.
+    /// This means that if you set a proxy both with this builde rand your
+    /// client's builder, this builder will overwrite the client's builder.
+    pub fn build_with(&mut self, client: ClientBuilder) -> Result<SrSettings, SRCError> {
+        let client = self.build_client(client)?;
+        let urls = self.urls.clone();
+        let authorization = self.authorization.clone();
+        Ok(SrSettings {
+            urls,
+            client,
+            authorization,
+        })
+    }
+
+    /// Build the settings.
+    ///
+    /// If you need your own client, see `build_with`.
     pub fn build(&mut self) -> Result<SrSettings, SRCError> {
-        let mut builder = Client::builder();
+        self.build_with(Client::builder())
+    }
+
+    fn build_client(&mut self, mut builder: ClientBuilder) -> Result<Client, SRCError> {
         if !self.headers.is_empty() {
             let mut header_map = header::HeaderMap::new();
             for (k, v) in self.headers.iter() {
@@ -153,18 +178,14 @@ impl SrSettingsBuilder {
             };
         }
         builder = builder.timeout(self.timeout);
-        let urls = self.urls.clone();
-        let authorization = self.authorization.clone();
         match builder.build() {
-            Ok(client) => Ok(SrSettings {
-                urls,
-                client,
-                authorization,
-            }),
-            Err(e) => Err(SRCError::non_retryable_with_cause(
-                e,
-                "could not create new client",
-            )),
+            Ok(client) => Ok(client),
+            Err(e) => {
+                return Err(SRCError::non_retryable_with_cause(
+                    e,
+                    "could not create new client",
+                ))
+            }
         }
     }
 }