Provide with_header method on client

This allows arbitrary headers to be included in requests to ClickHouse.

Cargo.toml

@@ -51,6 +51,7 @@ thiserror = "1.0.16"
 serde = "1.0.106"
 bytes = "1.5.0"
 tokio = { version = "1.0.1", features = ["rt", "macros"] }
+http = "0.2"
 hyper = { version = "0.14", features = ["client", "tcp", "http1", "stream"] }
 hyper-tls = { version = "0.5.0", optional = true }
 url = "2.1.1"

src/insert.rs

@@ -87,6 +87,10 @@ impl<T> Insert<T> {
 
         let mut builder = Request::post(url.as_str());
 
+        for (name, value) in &client.headers {
+            builder = builder.header(name.clone(), value.clone());
+        }
+
         if let Some(user) = &client.user {
             builder = builder.header("X-ClickHouse-User", user);
         }

src/lib.rs

@@ -8,6 +8,7 @@ extern crate static_assertions;
 
 use std::{collections::HashMap, sync::Arc, time::Duration};
 
+use http::{HeaderMap, HeaderName, HeaderValue};
 use hyper::client::connect::HttpConnector;
 #[cfg(feature = "tls")]
 use hyper_tls::HttpsConnector;
@@ -57,6 +58,7 @@ pub struct Client {
     password: Option<String>,
     compression: Compression,
     options: HashMap<String, String>,
+    headers: HeaderMap,
 }
 
 impl Default for Client {
@@ -93,6 +95,7 @@ impl Client {
             password: None,
             compression: Compression::default(),
             options: HashMap::new(),
+            headers: HeaderMap::new(),
         }
     }
 
@@ -170,6 +173,22 @@ impl Client {
         self
     }
 
+    /// Used to specify a header that will be passed to all queries.
+    ///
+    /// # Example
+    /// ```
+    /// # use clickhouse::Client;
+    /// Client::default().with_option("allow_nondeterministic_mutations", "1");
+    /// ```
+    pub fn with_header(
+        mut self,
+        name: impl Into<HeaderName>,
+        value: impl Into<HeaderValue>,
+    ) -> Self {
+        self.headers.append(name.into(), value.into());
+        self
+    }
+
     /// Starts a new INSERT statement.
     ///
     /// # Panics

src/query.rs

@@ -152,6 +152,10 @@ impl Query {
 
         let mut builder = Request::builder().method(method).uri(url.as_str());
 
+        for (name, value) in &self.client.headers {
+            builder = builder.header(name.clone(), value.clone());
+        }
+
         if content_length == 0 {
             builder = builder.header(CONTENT_LENGTH, "0");
         } else {