ureq 2.4.0

Simple, safe HTTP client
Documentation

ureq

A simple, safe HTTP client.

Ureq's first priority is being easy for you to use. It's great for anyone who wants a low-overhead HTTP client that just gets the job done. Works very well with HTTP APIs. Its features include cookies, JSON, HTTP proxies, HTTPS, and charset decoding.

Ureq is in pure Rust for safety and ease of understanding. It avoids using unsafe directly. It uses blocking I/O instead of async I/O, because that keeps the API simple and and keeps dependencies to a minimum. For TLS, ureq uses rustls or native-tls.

Version 2.0.0 was released recently and changed some APIs. See the changelog for details.

Usage

In its simplest form, ureq looks like this:

fn main() -> Result<(), ureq::Error> {
    let body: String = ureq::get("http://example.com")
        .set("Example-Header", "header value")
        .call()?
        .into_string()?;
    Ok(())
}

For more involved tasks, you'll want to create an Agent. An Agent holds a connection pool for reuse, and a cookie store if you use the "cookies" feature. An Agent can be cheaply cloned due to an internal Arc and all clones of an Agent share state among each other. Creating an Agent also allows setting options like the TLS configuration.

  use ureq::{Agent, AgentBuilder};
  use std::time::Duration;

  let agent: Agent = ureq::AgentBuilder::new()
      .timeout_read(Duration::from_secs(5))
      .timeout_write(Duration::from_secs(5))
      .build();
  let body: String = agent.get("http://example.com/page")
      .call()?
      .into_string()?;

  // Reuses the connection from previous request.
  let response: String = agent.put("http://example.com/upload")
      .set("Authorization", "example-token")
      .call()?
      .into_string()?;

Ureq supports sending and receiving json, if you enable the "json" feature:

  // Requires the `json` feature enabled.
  let resp: String = ureq::post("http://myapi.example.com/ingest")
      .set("X-My-Header", "Secret")
      .send_json(ureq::json!({
          "name": "martin",
          "rust": true
      }))?
      .into_string()?;

Error handling

ureq returns errors via Result<T, ureq::Error>. That includes I/O errors, protocol errors, and status code errors (when the server responded 4xx or 5xx)

use ureq::Error;

match ureq::get("http://mypage.example.com/").call() {
    Ok(response) => { /* it worked */},
    Err(Error::Status(code, response)) => {
        /* the server returned an unexpected status
           code (such as 400, 500 etc) */
    }
    Err(_) => { /* some kind of io/transport error */ }
}

More details on the Error type.

Features

To enable a minimal dependency tree, some features are off by default. You can control them when including ureq as a dependency.

ureq = { version = "*", features = ["json", "charset"] }

  • tls enables https. This is enabled by default.
  • native-certs makes the default TLS implementation use the OS' trust store (see TLS doc below).
  • cookies enables cookies.
  • json enables Response::into_json() and Request::send_json() via serde_json.
  • charset enables interpreting the charset part of the Content-Type header (e.g. Content-Type: text/plain; charset=iso-8859-1). Without this, the library defaults to Rust's built in utf-8.
  • socks-proxy enables proxy config using the socks4://, socks4a://, socks5:// and socks:// (equal to socks5://) prefix.
  • native-tls enables an adapter so you can pass a native_tls::TlsConnector instance to AgentBuilder::tls_connector. Due to the risk of diamond dependencies accidentally switching on an unwanted TLS implementation, native-tls is never picked up as a default or used by the crate level convenience calls (ureq::get etc) – it must be configured on the agent. The native-certs feature does nothing for native-tls.
  • gzip enables requests of gzip-compressed responses and decompresses them. This is enabled by default.
  • brotli enables requests brotli-compressed responses and decompresses them.

Plain requests

Most standard methods (GET, POST, PUT etc), are supported as functions from the top of the library (get(), post(), put(), etc).

These top level http method functions create a Request instance which follows a build pattern. The builders are finished using:

JSON

By enabling the ureq = { version = "*", features = ["json"] } feature, the library supports serde json.

Content-Length and Transfer-Encoding

The library will send a Content-Length header on requests with bodies of known size, in other words, those sent with .send_string(), .send_bytes(), .send_form(), or .send_json(). If you send a request body with .send(), which takes a Read of unknown size, ureq will send Transfer-Encoding: chunked, and encode the body accordingly. Bodyless requests (GETs and HEADs) are sent with .call() and ureq adds neither a Content-Length nor a Transfer-Encoding header.

If you set your own Content-Length or Transfer-Encoding header before sending the body, ureq will respect that header by not overriding it, and by encoding the body or not, as indicated by the headers you set.

let resp = ureq::post("http://my-server.com/ingest")
    .set("Transfer-Encoding", "chunked")
    .send_string("Hello world");

Character encoding

By enabling the ureq = { version = "*", features = ["charset"] } feature, the library supports sending/receiving other character sets than utf-8.

For response.into_string() we read the header Content-Type: text/plain; charset=iso-8859-1 and if it contains a charset specification, we try to decode the body using that encoding. In the absence of, or failing to interpret the charset, we fall back on utf-8.

Similarly when using request.send_string(), we first check if the user has set a ; charset=<whatwg charset> and attempt to encode the request body using that.

Proxying

ureq supports two kinds of proxies, HTTP CONNECT, SOCKS4 and SOCKS5, the former is always available while the latter must be enabled using the feature ureq = { version = "*", features = ["socks-proxy"] }.

Proxies settings are configured on an Agent (using [AgentBuilder]). All request sent through the agent will be proxied.

Example using HTTP CONNECT

fn proxy_example_1() -> std::result::Result<(), ureq::Error> {
    // Configure an http connect proxy. Notice we could have used
    // the http:// prefix here (it's optional).
    let proxy = ureq::Proxy::new("user:password@cool.proxy:9090")?;
    let agent = ureq::AgentBuilder::new()
        .proxy(proxy)
        .build();

    // This is proxied.
    let resp = agent.get("http://cool.server").call()?;
    Ok(())
}

Example using SOCKS5

fn proxy_example_2() -> std::result::Result<(), ureq::Error> {
    // Configure a SOCKS proxy.
    let proxy = ureq::Proxy::new("socks5://user:password@cool.proxy:9090")?;
    let agent = ureq::AgentBuilder::new()
        .proxy(proxy)
        .build();

    // This is proxied.
    let resp = agent.get("http://cool.server").call()?;
    Ok(())
}

HTTPS / TLS / SSL

On platforms that support rustls, ureq uses rustls. On other platforms, native-tls can be manually configured using [AgentBuilder::tls_connector].

You might want to use native-tls if you need to interoperate with servers that only support less-secure TLS configurations (rustls doesn't support TLS 1.0 and 1.1, for instance). You might also want to use it if you need to validate certificates for IP addresses, which are not currently supported in rustls.

Here's an example of constructing an Agent that uses native-tls. It requires the "native-tls" feature to be enabled.

  use std::sync::Arc;
  use ureq::Agent;

  let agent = ureq::AgentBuilder::new()
      .tls_connector(Arc::new(native_tls::TlsConnector::new().unwrap()))
      .build();

Trusted Roots

When you use rustls (tls feature), ureq defaults to trusting webpki-roots, a copy of the Mozilla Root program that is bundled into your program (and so won't update if your program isn't updated). You can alternately configure rustls-native-certs which extracts the roots from your OS' trust store. That means it will update when your OS is updated, and also that it will include locally installed roots.

When you use native-tls, ureq will use your OS' certificate verifier and root store.

Blocking I/O for simplicity

Ureq uses blocking I/O rather than Rust's newer asynchronous (async) I/O. Async I/O allows serving many concurrent requests without high costs in memory and OS threads. But it comes at a cost in complexity. Async programs need to pull in a runtime (usually async-std or tokio). They also need async variants of any method that might block, and of any method that might call another method that might block. That means async programs usually have a lot of dependencies - which adds to compile times, and increases risk.

The costs of async are worth paying, if you're writing an HTTP server that must serve many many clients with minimal overhead. However, for HTTP clients, we believe that the cost is usually not worth paying. The low-cost alternative to async I/O is blocking I/O, which has a different price: it requires an OS thread per concurrent request. However, that price is usually not high: most HTTP clients make requests sequentially, or with low concurrency.

That's why ureq uses blocking I/O and plans to stay that way. Other HTTP clients offer both an async API and a blocking API, but we want to offer a blocking API without pulling in all the dependencies required by an async API.


Ureq is inspired by other great HTTP clients like superagent and the fetch API.

If ureq is not what you're looking for, check out these other Rust HTTP clients: surf, reqwest, isahc, attohttpc, actix-web, and hyper.