kube_client/api/
remote_command.rs

1use std::time::Duration;
2
3use bytes::Bytes;
4use k8s_openapi::apimachinery::pkg::apis::meta::v1::Status;
5
6use futures::{
7    FutureExt, SinkExt, StreamExt,
8    channel::{mpsc, oneshot},
9};
10use serde::{Deserialize, Serialize};
11use thiserror::Error;
12use tokio::{
13    io::{AsyncRead, AsyncWrite, AsyncWriteExt, DuplexStream},
14    select, time,
15};
16use tokio_tungstenite::tungstenite as ws;
17
18use crate::client::Connection;
19
20use super::AttachParams;
21
22type StatusReceiver = oneshot::Receiver<Status>;
23type StatusSender = oneshot::Sender<Status>;
24
25type TerminalSizeReceiver = mpsc::Receiver<TerminalSize>;
26type TerminalSizeSender = mpsc::Sender<TerminalSize>;
27
28/// TerminalSize define the size of a terminal
29#[derive(Debug, Serialize, Deserialize)]
30#[cfg_attr(docsrs, doc(cfg(feature = "ws")))]
31#[serde(rename_all = "PascalCase")]
32pub struct TerminalSize {
33    /// width of the terminal
34    pub width: u16,
35    /// height of the terminal
36    pub height: u16,
37}
38
39/// Errors from attaching to a pod.
40#[derive(Debug, Error)]
41pub enum Error {
42    /// Failed to read from stdin
43    #[error("failed to read from stdin: {0}")]
44    ReadStdin(#[source] std::io::Error),
45
46    /// Failed to send stdin data to the pod
47    #[error("failed to send a stdin data: {0}")]
48    SendStdin(#[source] ws::Error),
49
50    /// Failed to write to stdout
51    #[error("failed to write to stdout: {0}")]
52    WriteStdout(#[source] std::io::Error),
53
54    /// Failed to write to stderr
55    #[error("failed to write to stderr: {0}")]
56    WriteStderr(#[source] std::io::Error),
57
58    /// Failed to receive a WebSocket message from the server.
59    #[error("failed to receive a WebSocket message: {0}")]
60    ReceiveWebSocketMessage(#[source] ws::Error),
61
62    // Failed to complete the background task
63    #[error("failed to complete the background task: {0}")]
64    Spawn(#[source] tokio::task::JoinError),
65
66    /// Failed to send close message.
67    #[error("failed to send a WebSocket close message: {0}")]
68    SendClose(#[source] ws::Error),
69
70    /// Failed to send ping message.
71    #[error("failed to send a WebSocket ping message: {0}")]
72    SendPing(#[source] ws::Error),
73
74    /// Failed to deserialize status object
75    #[error("failed to deserialize status object: {0}")]
76    DeserializeStatus(#[source] serde_json::Error),
77
78    /// Failed to send status object
79    #[error("failed to send status object")]
80    SendStatus,
81
82    /// Fail to serialize Terminalsize object
83    #[error("failed to serialize TerminalSize object: {0}")]
84    SerializeTerminalSize(#[source] serde_json::Error),
85
86    /// Fail to send terminal size message
87    #[error("failed to send terminal size message")]
88    SendTerminalSize(#[source] ws::Error),
89
90    /// Failed to set terminal size, tty need to be true to resize the terminal
91    #[error("failed to set terminal size, tty need to be true to resize the terminal")]
92    TtyNeedToBeTrue,
93}
94
95const MAX_BUF_SIZE: usize = 1024;
96
97/// Represents an attached process in a container for [`attach`] and [`exec`].
98///
99/// Provides access to `stdin`, `stdout`, and `stderr` if attached.
100///
101/// Use [`AttachedProcess::join`] to wait for the process to terminate.
102///
103/// [`attach`]: crate::Api::attach
104/// [`exec`]: crate::Api::exec
105#[cfg_attr(docsrs, doc(cfg(feature = "ws")))]
106pub struct AttachedProcess {
107    has_stdin: bool,
108    has_stdout: bool,
109    has_stderr: bool,
110    stdin_writer: Option<DuplexStream>,
111    stdout_reader: Option<DuplexStream>,
112    stderr_reader: Option<DuplexStream>,
113    status_rx: Option<StatusReceiver>,
114    terminal_resize_tx: Option<TerminalSizeSender>,
115    task: tokio::task::JoinHandle<Result<(), Error>>,
116}
117
118impl AttachedProcess {
119    pub(crate) fn new(connection: Connection, ap: &AttachParams) -> Self {
120        // To simplify the implementation, always create a pipe for stdin.
121        // The caller does not have access to it unless they had requested.
122        let (stdin_writer, stdin_reader) = tokio::io::duplex(ap.max_stdin_buf_size.unwrap_or(MAX_BUF_SIZE));
123        let (stdout_writer, stdout_reader) = if ap.stdout {
124            let (w, r) = tokio::io::duplex(ap.max_stdout_buf_size.unwrap_or(MAX_BUF_SIZE));
125            (Some(w), Some(r))
126        } else {
127            (None, None)
128        };
129        let (stderr_writer, stderr_reader) = if ap.stderr {
130            let (w, r) = tokio::io::duplex(ap.max_stderr_buf_size.unwrap_or(MAX_BUF_SIZE));
131            (Some(w), Some(r))
132        } else {
133            (None, None)
134        };
135        let (status_tx, status_rx) = oneshot::channel();
136        let (terminal_resize_tx, terminal_resize_rx) = if ap.tty {
137            let (w, r) = mpsc::channel(10);
138            (Some(w), Some(r))
139        } else {
140            (None, None)
141        };
142
143        let task = tokio::spawn(start_message_loop(
144            connection,
145            stdin_reader,
146            stdout_writer,
147            stderr_writer,
148            status_tx,
149            terminal_resize_rx,
150        ));
151
152        AttachedProcess {
153            has_stdin: ap.stdin,
154            has_stdout: ap.stdout,
155            has_stderr: ap.stderr,
156            task,
157            stdin_writer: Some(stdin_writer),
158            stdout_reader,
159            stderr_reader,
160            terminal_resize_tx,
161            status_rx: Some(status_rx),
162        }
163    }
164
165    /// Async writer to stdin.
166    /// ```no_run
167    /// # use kube_client::api::AttachedProcess;
168    /// # use tokio::io::{AsyncReadExt, AsyncWriteExt};
169    /// # async fn wrapper() -> Result<(), Box<dyn std::error::Error>> {
170    /// # let attached: AttachedProcess = todo!();
171    /// let mut stdin_writer = attached.stdin().unwrap();
172    /// stdin_writer.write(b"foo\n").await?;
173    /// # Ok(())
174    /// # }
175    /// ```
176    /// Only available if [`AttachParams`](super::AttachParams) had `stdin`.
177    pub fn stdin(&mut self) -> Option<impl AsyncWrite + Unpin + use<>> {
178        if !self.has_stdin {
179            return None;
180        }
181        self.stdin_writer.take()
182    }
183
184    /// Async reader for stdout outputs.
185    /// ```no_run
186    /// # use kube_client::api::AttachedProcess;
187    /// # use tokio::io::{AsyncReadExt, AsyncWriteExt};
188    /// # async fn wrapper() -> Result<(), Box<dyn std::error::Error>> {
189    /// # let attached: AttachedProcess = todo!();
190    /// let mut stdout_reader = attached.stdout().unwrap();
191    /// let mut buf = [0u8; 4];
192    /// stdout_reader.read_exact(&mut buf).await?;
193    /// # Ok(())
194    /// # }
195    /// ```
196    /// Only available if [`AttachParams`](super::AttachParams) had `stdout`.
197    pub fn stdout(&mut self) -> Option<impl AsyncRead + Unpin + use<>> {
198        if !self.has_stdout {
199            return None;
200        }
201        self.stdout_reader.take()
202    }
203
204    /// Async reader for stderr outputs.
205    /// ```no_run
206    /// # use kube_client::api::AttachedProcess;
207    /// # use tokio::io::{AsyncReadExt, AsyncWriteExt};
208    /// # async fn wrapper() -> Result<(), Box<dyn std::error::Error>> {
209    /// # let attached: AttachedProcess = todo!();
210    /// let mut stderr_reader = attached.stderr().unwrap();
211    /// let mut buf = [0u8; 4];
212    /// stderr_reader.read_exact(&mut buf).await?;
213    /// # Ok(())
214    /// # }
215    /// ```
216    /// Only available if [`AttachParams`](super::AttachParams) had `stderr`.
217    pub fn stderr(&mut self) -> Option<impl AsyncRead + Unpin + use<>> {
218        if !self.has_stderr {
219            return None;
220        }
221        self.stderr_reader.take()
222    }
223
224    /// Abort the background task, causing remote command to fail.
225    #[inline]
226    pub fn abort(&self) {
227        self.task.abort();
228    }
229
230    /// Waits for the remote command task to complete.
231    pub async fn join(self) -> Result<(), Error> {
232        self.task.await.unwrap_or_else(|e| Err(Error::Spawn(e)))
233    }
234
235    /// Take a future that resolves with any status object or when the sender is dropped.
236    ///
237    /// Returns `None` if called more than once.
238    pub fn take_status(&mut self) -> Option<impl Future<Output = Option<Status>> + use<>> {
239        self.status_rx.take().map(|recv| recv.map(|res| res.ok()))
240    }
241
242    /// Async writer to change the terminal size
243    /// ```no_run
244    /// # use kube_client::api::{AttachedProcess, TerminalSize};
245    /// # use tokio::io::{AsyncReadExt, AsyncWriteExt};
246    /// # use futures::SinkExt;
247    /// # async fn wrapper() -> Result<(), Box<dyn std::error::Error>> {
248    /// # let attached: AttachedProcess = todo!();
249    /// let mut terminal_size_writer = attached.terminal_size().unwrap();
250    /// terminal_size_writer.send(TerminalSize{
251    ///     height: 100,
252    ///     width: 200,
253    /// }).await?;
254    /// # Ok(())
255    /// # }
256    /// ```
257    /// Only available if [`AttachParams`](super::AttachParams) had `tty`.
258    pub fn terminal_size(&mut self) -> Option<TerminalSizeSender> {
259        self.terminal_resize_tx.take()
260    }
261}
262
263// theses values come from here: https://github.com/kubernetes/kubernetes/blob/master/staging/src/k8s.io/apimachinery/pkg/util/remotecommand/constants.go#L57
264const STDIN_CHANNEL: u8 = 0;
265const STDOUT_CHANNEL: u8 = 1;
266const STDERR_CHANNEL: u8 = 2;
267// status channel receives `Status` object on exit.
268const STATUS_CHANNEL: u8 = 3;
269// resize channel is use to send TerminalSize object to change the size of the terminal
270const RESIZE_CHANNEL: u8 = 4;
271/// Used to signal that a channel has reached EOF. Only works on V5 of the protocol.
272const CLOSE_CHANNEL: u8 = 255;
273
274async fn start_message_loop(
275    connection: Connection,
276    stdin: impl AsyncRead + Unpin,
277    mut stdout: Option<impl AsyncWrite + Unpin>,
278    mut stderr: Option<impl AsyncWrite + Unpin>,
279    status_tx: StatusSender,
280    mut terminal_size_rx: Option<TerminalSizeReceiver>,
281) -> Result<(), Error> {
282    let supports_stream_close = connection.supports_stream_close();
283    let stream = connection.into_stream();
284    let mut stdin_stream = tokio_util::io::ReaderStream::new(stdin);
285    let (mut server_send, raw_server_recv) = stream.split();
286    // Work with filtered messages to reduce noise.
287    let mut server_recv = raw_server_recv.filter_map(filter_message).boxed();
288    let mut have_terminal_size_rx = terminal_size_rx.is_some();
289
290    // True until we reach EOF for stdin.
291    let mut stdin_is_open = true;
292
293    let mut ping_interval = time::interval(Duration::from_secs(60));
294    ping_interval.set_missed_tick_behavior(time::MissedTickBehavior::Delay);
295    ping_interval.reset();
296
297    loop {
298        let terminal_size_next = async {
299            match terminal_size_rx.as_mut() {
300                Some(tmp) => Some(tmp.next().await),
301                None => None,
302            }
303        };
304
305        select! {
306            _ = ping_interval.tick() => {
307                // send a ping to keep an idle connection alive
308                server_send
309                    .send(ws::Message::Ping(Bytes::new()))
310                    .await
311                    .map_err(Error::SendPing)?;
312            },
313
314            server_message = server_recv.next() => {
315                match server_message {
316                    Some(Ok(Message::Stdout(bin))) => {
317                        if let Some(stdout) = stdout.as_mut() {
318                            stdout.write_all(&bin[1..]).await.map_err(Error::WriteStdout)?;
319                        }
320                    },
321                    Some(Ok(Message::Stderr(bin))) => {
322                        if let Some(stderr) = stderr.as_mut() {
323                            stderr.write_all(&bin[1..]).await.map_err(Error::WriteStderr)?;
324                        }
325                    },
326                    Some(Ok(Message::Status(bin))) => {
327                        let status = serde_json::from_slice::<Status>(&bin[1..]).map_err(Error::DeserializeStatus)?;
328                        status_tx.send(status).map_err(|_| Error::SendStatus)?;
329                        break
330                    },
331                    Some(Err(err)) => {
332                        return Err(Error::ReceiveWebSocketMessage(err));
333                    },
334                    None => {
335                        // Connection closed properly
336                        break
337                    },
338                }
339            },
340            stdin_message = stdin_stream.next(), if stdin_is_open => {
341                match stdin_message {
342                    Some(Ok(bytes)) => {
343                        if !bytes.is_empty() {
344                            let mut vec = Vec::with_capacity(bytes.len() + 1);
345                            vec.push(STDIN_CHANNEL);
346                            vec.extend_from_slice(&bytes[..]);
347                            server_send
348                                .send(ws::Message::binary(vec))
349                                .await
350                                .map_err(Error::SendStdin)?;
351                        }
352                    },
353                    Some(Err(err)) => {
354                        return Err(Error::ReadStdin(err));
355                    }
356                    None => {
357                        // Stdin closed (writer half dropped).
358                        // Let the server know we reached the end of stdin.
359                        if supports_stream_close {
360                            // Signal stdin has reached EOF.
361                            // See: https://github.com/kubernetes/kubernetes/blob/master/staging/src/k8s.io/apimachinery/pkg/util/httpstream/wsstream/conn.go#L346
362                            let vec = vec![CLOSE_CHANNEL, STDIN_CHANNEL];
363                            server_send
364                                .send(ws::Message::binary(vec))
365                                .await
366                                .map_err(Error::SendStdin)?;
367                        } else {
368                            // Best we can do is trigger the whole websocket to close.
369                            // We may miss out on any remaining stdout data that has not
370                            // been sent yet.
371                            server_send.close().await.map_err(Error::SendClose)?;
372                        }
373
374                        // Do not check stdin_stream for data in future loops.
375                        stdin_is_open = false;
376                    }
377                }
378            },
379            Some(terminal_size_message) = terminal_size_next, if have_terminal_size_rx => {
380                match terminal_size_message {
381                    Some(new_size) => {
382                        let new_size = serde_json::to_vec(&new_size).map_err(Error::SerializeTerminalSize)?;
383                        let mut vec = Vec::with_capacity(new_size.len() + 1);
384                        vec.push(RESIZE_CHANNEL);
385                        vec.extend_from_slice(&new_size[..]);
386                        server_send.send(ws::Message::Binary(vec.into())).await.map_err(Error::SendTerminalSize)?;
387                    },
388                    None => {
389                        have_terminal_size_rx = false;
390                    }
391                }
392            },
393        }
394    }
395
396    Ok(())
397}
398
399/// Channeled messages from the server.
400enum Message {
401    /// To Stdout channel (1)
402    Stdout(Vec<u8>),
403    /// To stderr channel (2)
404    Stderr(Vec<u8>),
405    /// To error/status channel (3)
406    Status(Vec<u8>),
407}
408
409// Filter to reduce all the possible WebSocket messages into a few we expect to receive.
410async fn filter_message(wsm: Result<ws::Message, ws::Error>) -> Option<Result<Message, ws::Error>> {
411    match wsm {
412        // The protocol only sends binary frames.
413        // Message of size 1 (only channel number) is sent on connection.
414        Ok(ws::Message::Binary(bin)) if bin.len() > 1 => match bin[0] {
415            STDOUT_CHANNEL => Some(Ok(Message::Stdout(bin.into()))),
416            STDERR_CHANNEL => Some(Ok(Message::Stderr(bin.into()))),
417            STATUS_CHANNEL => Some(Ok(Message::Status(bin.into()))),
418            // We don't receive messages to stdin and resize channels.
419            _ => None,
420        },
421        // Ignore any other message types.
422        // We can ignore close message because the server never sends anything special.
423        // The connection terminates on `None`.
424        Ok(_) => None,
425        // Fatal errors. `WebSocketStream` turns `ConnectionClosed` and `AlreadyClosed` into `None`.
426        // So these are unrecoverables.
427        Err(err) => Some(Err(err)),
428    }
429}
kube_client/api/remote_command.rs

kube_client/api/
remote_command.rs
