Remove various caveats from the readme and code

CHANGELOG.md

@@ -6,6 +6,9 @@ Record breaking or significant changes here. All dates are UTC.
 
 Put changes for the upcoming release here!
 
+- Changed (Rust API, lang bindings): the `TS_RS_EXPERIMENT` environment variable is no longer required to use the
+  library. The library logs a warning during initialization, as a reminder that it's still work-in-progress software.
+
 ## [0.5.0](https://github.com/tailscale/tailscale-rs/releases/tag/v0.5.0) - 2026-08-14
 
 - **Breaking** (Rust API, lang bindings, ts_control): Support for `ephemeral`

README.md

@@ -7,14 +7,8 @@ https://tailscale.com
 
 `tailscale-rs` is a work-in-progress Tailscale library written in Rust, with language bindings to C, Elixir, and Python.
 
-> [!CAUTION]
-> This software is unstable and insecure.
->
-> We welcome enthusiasm and interest, but please **do not** build production software using these
-> libraries or rely on it for data privacy until we have a chance to batten down some hatches
-> and complete a third-party audit.
->
-> See [Caveats](#caveats) for more details.
+> [!NOTE]
+> This software is under active development. See [Caveats](#caveats) for more details.
 
 ## Getting Started
 
@@ -72,32 +66,28 @@ async fn main() -> Result<(), Box<dyn Error>> {
 This software is still a work-in-progress! We are providing it in the open at this stage out of a belief in open-source
 and to see where the community runs with it, but please be aware of a few important considerations:
 
-- This implementation contains unaudited cryptography and hasn't undergone a comprehensive security analysis.
-  Conservatively, assume there could be a critical security hole meaning anything you send or receive could be in the
-  clear on the public Internet.
-- There are no compatibility guarantees at the moment. This is early-days software &mdash; we may break dependent code
-  in order to get things right.
-- We currently rely on DERP relays for all communication. Direct connections via NAT holepunching will be a seamless
-  upgrade in the future, but for now, this puts a cap on data throughput.
-- The `TS_RS_EXPERIMENT` environment variable is required to be set to `this_is_unstable_software`
-  for all code linked against `tailscale-rs`; this includes Rust, C, Elixir, and Python code. We'll remove this
-  requirement after a third-party code/cryptography audit and any necessary fixes.
+- There are no compatibility guarantees at the moment. We may break dependent code in order to get things right,
+  although we will try to avoid doing so gratuitously.
+- Direct connections via NAT traversal is a work in progress. Communication may fall back to DERP relaying in more cases,
+  with a corresponding hit to latency and throughput.
+- Core networking functionality is implemented. Many other features are still either in progress or not implemented yet.
+  See [Status](#status) for details.
 
-## Versioning, Releases, and Compatability
+We encourage you to experiment with this library and build things with it, as long as you're okay with these caveats.
 
-We follow semver and aim to make a point release roughly monthly. Since we are pre-1.0, we make no
-backwards-compatability guarantees. We are aiming to have a stable 1.0 release as soon as we can, but we currently don't
-have a timeline.
+## Versioning, Releases, and Compatibility
+
+We follow semver and aim to make a point release roughly monthly. Since we are pre-1.0, we make no strong
+backwards-compatibility guarantees.
 
 ## MSRV and Edition
 
 The current MSRV is 1.94.1. The current edition is Rust 2024.
 
 `tailscale-rs` has a rolling MSRV (Minimum Supported Rust Version) policy to support the current and previous Rust
-compiler versions, and the latest
-[edition of Rust](https://doc.rust-lang.org/edition-guide/editions/index.html).
+compiler versions, and the latest [edition of Rust](https://doc.rust-lang.org/edition-guide/editions/index.html).
 
-We may lag the latest version/edition in rare cases for our dependencies to catch up and for us to perform any necessary
+We may periodically lag the MSRV behind this latest version/edition in rare cases for our dependencies to catch up and for us to perform any necessary
 fixes.
 
 ## Platform Support
@@ -110,9 +100,8 @@ We support the following platforms and architectures:
 
 ## Status
 
-`tailscale-rs` is a work-in-progress - we're still rapidly iterating, fixing bugs, and adding new features. We aim to
-keep this section up-to-date, but our [issue tracker](https://github.com/tailscale/tailscale-rs/issues)
-is the best way to see the latest updates.
+`tailscale-rs` is a work-in-progress. We're still rapidly iterating, fixing bugs, and adding new features.
+We aim to keep this section up-to-date, but our [issue tracker](https://github.com/tailscale/tailscale-rs/issues) is the best way to see the latest updates.
 
 ### Implemented
 
@@ -133,7 +122,6 @@ timeline or completion:
 
 - Direct connections (NAT traversal, STUN, and Disco)
 - Peer lookups (addressing peers by hostname)
-- Third-party code and cryptography audit
 
 ### Unsupported
 

examples/README.md

@@ -14,9 +14,6 @@ tailnet, referred to as `$AUTH_KEY` below
 examples take care of that for you
 - A tailnet policy configured to allow access between your local machine and the example code
 
-Also note the `TS_RS_EXPERIMENT=this_is_unstable_software` environment variable in all the examples
-below; for an explanation, see [the Caveats section of the README](../README.md#caveats).
-
 ## Overview
 
 Brief descriptions and links to each example.

examples/axum/README.md

@@ -7,7 +7,7 @@ An `axum`-based HTTP server that serves a simple webpage over the tailnet. This
 `tailscale-rs` to be compiled with the `axum` feature:
 
 ```sh
-$ TS_RS_EXPERIMENT=this_is_unstable_software cargo run --example axum --features axum -- --auth-key $AUTH_KEY --key-file tsrs_keys.json
+$ cargo run --example axum --features axum -- --auth-key $AUTH_KEY --key-file tsrs_keys.json
 ...
 INFO axum: http server listening url=http://<tailnet IP>:80/index.html
 ```

examples/peer_ping/README.md

@@ -23,7 +23,7 @@ Then, in another terminal, run the example:
 
 ```sh
 # Terminal 2
-$ TS_RS_EXPERIMENT=this_is_unstable_software cargo run --example peer_ping -- --auth-key $AUTH_KEY --key-file tsrs_keys.json --peer <tailnet IP>:5678 
+$ cargo run --example peer_ping -- --auth-key $AUTH_KEY --key-file tsrs_keys.json --peer <tailnet IP>:5678 
 ...
 INFO ts_runtime::multiderp: new home derp region selected region_id=1 latency_ms=12.223305702209473
 ...

examples/tcp_echo/README.md

@@ -9,7 +9,7 @@ For this example, you can use netcat (`nc`) to test the server. First, start the
 
 ```sh
 # Terminal 1
-$ TS_RS_EXPERIMENT=this_is_unstable_software cargo run --example tcp_echo -- --auth-key $AUTH_KEY --key-file tsrs_keys.json 
+$ cargo run --example tcp_echo -- --auth-key $AUTH_KEY --key-file tsrs_keys.json 
 ...
 INFO tcp_echo: listening_addr=<tailnet IP>:1234
 ...

src/error.rs

@@ -25,14 +25,6 @@ pub enum Error {
     #[error("an error writing out the key file")]
     KeyFileWrite,
 
-    /// The environment variable `TS_RS_EXPERIMENT` was not set.
-    ///
-    /// The end-user must set `TS_RS_EXPERIMENT=this_is_unstable_software` to acknowledge that tailscale-rs
-    /// is early-days experimental software containing bugs, unvalidated cryptography, and no stability
-    /// or compatibility guarantees.
-    #[error("the environment variable `{}` was not set", crate::ENV_MAGIC_VAR)]
-    UnstableEnvVar,
-
     /// An error occurred which can not be anticipated or handled by a library user.
     ///
     /// This is likely due to a bug in our code or a rare and unexpected error.

src/lib.rs

@@ -57,10 +57,6 @@
 //!
 //! ## Using `tailscale`
 //!
-//! To use this crate or the language bindings, you will need to set the `TS_RS_EXPERIMENT` env var
-//! to `this_is_unstable_software`. We'll remove this requirement after a third-party code/cryptography
-//! audit and any necessary fixes.
-//!
 //! Under the hood, we use Tokio for our async runtime. You must also use Tokio, any kind and most
 //! configurations of Tokio runtimes should work, but there must be one available when you call any
 //! async API functions. The easiest way to do this is to use `#[tokio::main]`, see the
@@ -189,7 +185,9 @@ impl Device {
     /// # Ok(()) }
     /// ```
     pub async fn new(config: &Config, auth_key: Option<String>) -> Result<Self, Error> {
-        check_magic_env()?;
+        tracing::warn!(
+            "tailscale-rs is early software in active development, expect more bugs and missing features than usual."
+        );
 
         let keys = (&config.key_state).into();
         let rt = ts_runtime::Runtime::spawn(ts_runtime::Config {
@@ -376,24 +374,3 @@ pub mod keys {
         NodeKeyPair, NodePrivateKey, NodePublicKey, NodeState, PersistState,
     };
 }
-
-const ENV_MAGIC_VAR: &str = "TS_RS_EXPERIMENT";
-const ENV_MAGIC_VALUE: &str = "this_is_unstable_software";
-
-fn check_magic_env() -> Result<(), Error> {
-    if std::env::var(ENV_MAGIC_VAR).as_deref() != Ok(ENV_MAGIC_VALUE) {
-        let warning = format!(
-            "
-check failed: set {ENV_MAGIC_VAR}={ENV_MAGIC_VALUE} to acknowledge that tailscale-rs is early-days
-experimental software containing bugs, unvalidated cryptography, and no stability or compatibility
-guarantees.
-            "
-        );
-
-        eprintln!("{}", warning.trim());
-
-        return Err(Error::UnstableEnvVar);
-    };
-
-    Ok(())
-}

tests/basic.rs

@@ -197,7 +197,5 @@ async fn test_udp_unidir(tx: &UdpSocket, rx: &UdpSocket) {
 }
 
 async fn make_ts_device() -> Result<Device, Error> {
-    unsafe { std::env::set_var("TS_RS_EXPERIMENT", "this_is_unstable_software") };
-
     Device::new(&Config::default(), Some(ts_test_util::auth_key().unwrap())).await
 }

ts_python/README.md

@@ -36,7 +36,7 @@ if __name__ == "__main__":
 To run this demo:
 
 ```console
-$ TS_RS_EXPERIMENT=this_is_unstable_software python demo.py
+$ python demo.py
 ```
 
 ## Building and Usage

ts_python/examples/README.md

@@ -16,9 +16,6 @@ For all the examples, you'll need:
 - A tailnet policy configured to allow access between your local machine and the example code, and
 between the examples themselves
 
-Also note the `TS_RS_EXPERIMENT=this_is_unstable_software` environment variable is required for all
-the examples below; for an explanation, see [the Caveats section of the README](../../README.md#caveats).
-
 ## [UDP](udp)
 
 A UDP sender and receiver. The sender sends UDP datagrams to the receiver over the tailnet.

ts_python/examples/udp/README.md

@@ -10,7 +10,7 @@ First, start the receiver:
 
 ```sh
 # Terminal 1
-$ TS_RS_EXPERIMENT=this_is_unstable_software ./recv.py $AUTH_KEY_1 5678
+$ ./recv.py $AUTH_KEY_1 5678
 ...
 [<recv IPv4>:5678] udp bound, local endpoint: ('<recv IPv4>', 5678)
 ...
@@ -20,7 +20,7 @@ Then, in another terminal, start the sender:
 
 ```sh
 # Terminal 2
-$ TS_RS_EXPERIMENT=this_is_unstable_software ./send.py $AUTH_KEY_2 <recv IPv4> 5678 
+$ ./send.py $AUTH_KEY_2 <recv IPv4> 5678 
 ...
 [<send IPv4>:1234] udp bound, local endpoint: ('<send IPv4>', 1234)
 [<send IPv4>:1234-><recv IPv4>:5678|0001] sent message: b'HELLO'

ts_python/examples/udp/recv.py

@@ -33,7 +33,7 @@ async def main(auth_key: str, bind_port: int) -> None:
 if __name__ == "__main__":
     parser = argparse.ArgumentParser(
         description="UDP receiver built with `tailscale-py`",
-        usage="TS_RS_EXPERIMENT=this_is_unstable_software %(prog)s [options]",
+        usage="%(prog)s [options]",
     )
     parser.add_argument("auth_key", help="auth key to register with tailnet")
     parser.add_argument("bind_port", help="local UDP port to bind", type=int)

ts_python/examples/udp/send.py

@@ -36,7 +36,7 @@ async def main(auth_key: str, peer_ip: str, peer_port: int) -> None:
 if __name__ == "__main__":
     parser = argparse.ArgumentParser(
         description="UDP sender built with `tailscale-py`",
-        usage="TS_RS_EXPERIMENT=this_is_unstable_software %(prog)s [options]",
+        usage="%(prog)s [options]",
     )
     parser.add_argument("auth_key", help="auth key to register with tailnet")
     parser.add_argument("peer_ip", help="peer's tailnet IP address")

ts_tunnel/README.md

@@ -21,8 +21,8 @@ tests).
 
 ## Security limitations
 
-This crate has not yet been subjected to a code audit by expert cryptography engineers. Conservatively, assume that
-there could be a critical security hole that exposes your traffic to attackers.
+The code in this crate has been reviewed by third-party security experts. However, it's still relatively young code
+that's still being worked on, so depending on your comfort level you may want to conduct your own evaluation.
 
 As stated above, this crate by itself is NOT a complete implementation of WireGuard, and should not be used as one.