Add x-elastic-client-meta header

Author: swallez

Diff for: elasticsearch/Cargo.toml

@@ -29,6 +29,7 @@ rustls-tls = ["reqwest/rustls-tls"]
 base64 = "^0.11"
 bytes = "^1.0"
 dyn-clone = "~1"
+lazy_static = "1.4"
 percent-encoding = "2.1.0"
 reqwest = { version = "~0.11", default-features = false, features = ["gzip", "json"] }
 url = "^2.1"
@@ -45,6 +46,7 @@ futures = "0.3.1"
 http = "0.2"
 hyper = { version = "0.14", default-features = false, features = ["tcp", "stream", "server"] }
 os_type = "2.2"
+regex="1.4"
 sysinfo = "0.12.0"
 textwrap = "^0.11"
 tokio = { version = "1.0", default-features = false, features = ["macros", "net", "time", "rt-multi-thread"] }

Diff for: elasticsearch/build.rs

@@ -20,7 +20,8 @@ extern crate rustc_version;
 use rustc_version::{version_meta, Channel};
 
 fn main() {
-    match version_meta().unwrap().channel {
+    let version = version_meta().unwrap();
+    match version.channel {
         Channel::Stable => {
             println!("cargo:rustc-cfg=RUSTC_IS_STABLE");
         }
@@ -34,4 +35,11 @@ fn main() {
             println!("cargo:rustc-cfg=RUSTC_IS_DEV");
         }
     }
+
+    let semver = version.semver;
+    let mut rustcv: String = format!("{}.{}.{}", semver.major, semver.minor, semver.patch);
+    if version.channel != Channel::Stable {
+        rustcv.push('p');
+    }
+    println!("cargo:rustc-env=RUSTC_VERSION={}", rustcv);
 }

Diff for: elasticsearch/src/http/transport.rs

@@ -37,6 +37,7 @@ use crate::{
 };
 use base64::write::EncoderWriter as Base64Encoder;
 use bytes::BytesMut;
+use lazy_static::lazy_static;
 use serde::Serialize;
 use std::{
     error, fmt,
@@ -97,6 +98,37 @@ impl fmt::Display for BuildError {
 /// Default address to Elasticsearch running on `http://localhost:9200`
 pub static DEFAULT_ADDRESS: &str = "http://localhost:9200";
 
+lazy_static! {
+    /// Client metadata header: service, language, transport, followed by additional information
+    static ref CLIENT_META: String = build_meta();
+}
+
+fn build_meta() -> String {
+    let mut version_parts = env!("CARGO_PKG_VERSION").split(&['.', '-'][..]);
+    let mut version = String::new();
+
+    // major.minor.patch followed with an optional 'p' for preliminary versions
+    version.push_str(version_parts.next().unwrap());
+    version.push('.');
+    version.push_str(version_parts.next().unwrap());
+    version.push('.');
+    version.push_str(version_parts.next().unwrap());
+    if version_parts.next().is_some() {
+        version.push('p');
+    }
+
+    let rustc = env!("RUSTC_VERSION");
+    let mut meta = format!("es={},rs={},t={}", version, rustc, version);
+
+    if cfg!(feature = "native-tls") {
+        meta.push_str(",tls=n");
+    } else if cfg!(feature = "rustls-tls") {
+        meta.push_str(",tls=r");
+    }
+
+    meta
+}
+
 /// Builds a HTTP transport to make API calls to Elasticsearch
 pub struct TransportBuilder {
     client_builder: reqwest::ClientBuilder,
@@ -108,6 +140,7 @@ pub struct TransportBuilder {
     proxy_credentials: Option<Credentials>,
     disable_proxy: bool,
     headers: HeaderMap,
+    meta_header: bool,
     timeout: Option<Duration>,
 }
 
@@ -128,6 +161,7 @@ impl TransportBuilder {
             proxy_credentials: None,
             disable_proxy: false,
             headers: HeaderMap::new(),
+            meta_header: true,
             timeout: None,
         }
     }
@@ -187,6 +221,16 @@ impl TransportBuilder {
         self
     }
 
+    /// Whether to send a `x-elastic-client-meta` header that describes the runtime environment.
+    ///
+    /// This header contains information that is similar to what could be found in `User-Agent`. Using a separate
+    /// header allows applications to use `User-Agent` for their own needs, e.g. to identify application version
+    /// or other environment information. Defaults to `true`.
+    pub fn enable_meta_header(mut self, enable: bool) -> Self {
+        self.meta_header = enable;
+        self
+    }
+
     /// Sets a global request timeout for the client.
     ///
     /// The timeout is applied from when the request starts connecting until the response body has finished.
@@ -270,6 +314,7 @@ impl TransportBuilder {
             client,
             conn_pool: self.conn_pool,
             credentials: self.credentials,
+            send_meta: self.meta_header,
         })
     }
 }
@@ -309,6 +354,7 @@ pub struct Transport {
     client: reqwest::Client,
     credentials: Option<Credentials>,
     conn_pool: Box<dyn ConnectionPool>,
+    send_meta: bool,
 }
 
 impl Transport {
@@ -396,13 +442,20 @@ impl Transport {
         }
 
         // default headers first, overwrite with any provided
-        let mut request_headers = HeaderMap::with_capacity(3 + headers.len());
+        let mut request_headers = HeaderMap::with_capacity(4 + headers.len());
         request_headers.insert(CONTENT_TYPE, HeaderValue::from_static(DEFAULT_CONTENT_TYPE));
         request_headers.insert(ACCEPT, HeaderValue::from_static(DEFAULT_ACCEPT));
         request_headers.insert(USER_AGENT, HeaderValue::from_static(DEFAULT_USER_AGENT));
         for (name, value) in headers {
             request_headers.insert(name.unwrap(), value);
         }
+        // if meta header enabled, send it last so that it's not overridden.
+        if self.send_meta {
+            request_headers.insert(
+                "x-elastic-client-meta",
+                HeaderValue::from_static(CLIENT_META.as_str()),
+            );
+        }
 
         request_builder = request_builder.headers(request_headers);
 
@@ -601,9 +654,10 @@ impl ConnectionPool for CloudConnectionPool {
 
 #[cfg(test)]
 pub mod tests {
+    use super::*;
     #[cfg(any(feature = "native-tls", feature = "rustls-tls"))]
     use crate::auth::ClientCertificate;
-    use crate::http::transport::{CloudId, Connection, SingleNodeConnectionPool, TransportBuilder};
+    use regex::Regex;
     use url::Url;
 
     #[test]
@@ -742,4 +796,12 @@ pub mod tests {
         let conn = Connection::new(url);
         assert_eq!(conn.url.as_str(), "http://10.1.2.3/");
     }
+
+    #[test]
+    pub fn test_meta_header() {
+        let re = Regex::new(r"^es=[0-9]{1,2}\.[0-9]{1,2}\.[0-9]{1,3}p?,rs=[0-9]{1,2}\.[0-9]{1,2}\.[0-9]{1,3}p?,t=[0-9]{1,2}\.[0-9]{1,2}\.[0-9]{1,3}p?(,tls=[rn])?$").unwrap();
+        let x: &str = CLIENT_META.as_str();
+        println!("{}", x);
+        assert!(re.is_match(x));
+    }
 }