kube_runtime/wait.rs
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//! Waits for objects to reach desired states
use std::{future, pin::pin};
use futures::TryStreamExt;
use kube_client::{Api, Resource};
use serde::de::DeserializeOwned;
use std::fmt::Debug;
use thiserror::Error;
use crate::watcher::{self, watch_object};
#[derive(Debug, Error)]
pub enum Error {
#[error("failed to probe for whether the condition is fulfilled yet: {0}")]
ProbeFailed(#[source] watcher::Error),
}
/// Watch an object, and wait for some condition `cond` to return `true`.
///
/// `cond` is passed `Some` if the object is found, otherwise `None`.
///
/// The object is returned when the condition is fulfilled.
///
/// # Caveats
///
/// Keep in mind that the condition is typically fulfilled by an external service, which might not even be available. `await_condition`
/// does *not* automatically add a timeout. If this is desired, wrap it in [`tokio::time::timeout`].
///
/// # Errors
///
/// Fails if the type is not known to the Kubernetes API, or if the [`Api`] does not have
/// permission to `watch` and `list` it.
///
/// Does *not* fail if the object is not found.
///
/// # Usage
///
/// ```
/// use k8s_openapi::apiextensions_apiserver::pkg::apis::apiextensions::v1::CustomResourceDefinition;
/// use kube::{Api, runtime::wait::{await_condition, conditions}};
/// # async fn wrapper() -> Result<(), Box<dyn std::error::Error>> {
/// # let client: kube::Client = todo!();
///
/// let crds: Api<CustomResourceDefinition> = Api::all(client);
/// // .. create or apply a crd here ..
/// let establish = await_condition(crds, "foos.clux.dev", conditions::is_crd_established());
/// let _ = tokio::time::timeout(std::time::Duration::from_secs(10), establish).await?;
/// # Ok(())
/// # }
/// ```
#[allow(clippy::missing_panics_doc)] // watch never actually terminates, expect cannot fail
pub async fn await_condition<K>(api: Api<K>, name: &str, cond: impl Condition<K>) -> Result<Option<K>, Error>
where
K: Clone + Debug + Send + DeserializeOwned + Resource + 'static,
{
// Skip updates until the condition is satisfied.
let mut stream = pin!(watch_object(api, name).try_skip_while(|obj| {
let matches = cond.matches_object(obj.as_ref());
future::ready(Ok(!matches))
}));
// Then take the first update that satisfies the condition.
let obj = stream
.try_next()
.await
.map_err(Error::ProbeFailed)?
.expect("stream must not terminate");
Ok(obj)
}
/// A trait for condition functions to be used by [`await_condition`]
///
/// Note that this is auto-implemented for functions of type `fn(Option<&K>) -> bool`.
///
/// # Usage
///
/// ```
/// use kube::runtime::wait::Condition;
/// use k8s_openapi::api::core::v1::Pod;
/// fn my_custom_condition(my_cond: &str) -> impl Condition<Pod> + '_ {
/// move |obj: Option<&Pod>| {
/// if let Some(pod) = &obj {
/// if let Some(status) = &pod.status {
/// if let Some(conds) = &status.conditions {
/// if let Some(pcond) = conds.iter().find(|c| c.type_ == my_cond) {
/// return pcond.status == "True";
/// }
/// }
/// }
/// }
/// false
/// }
/// }
/// ```
pub trait Condition<K> {
fn matches_object(&self, obj: Option<&K>) -> bool;
/// Returns a `Condition` that holds if `self` does not
///
/// # Usage
///
/// ```
/// # use kube_runtime::wait::Condition;
/// let condition: fn(Option<&()>) -> bool = |_| true;
/// assert!(condition.matches_object(None));
/// assert!(!condition.not().matches_object(None));
/// ```
fn not(self) -> conditions::Not<Self>
where
Self: Sized,
{
conditions::Not(self)
}
/// Returns a `Condition` that holds if `self` and `other` both do
///
/// # Usage
///
/// ```
/// # use kube_runtime::wait::Condition;
/// let cond_false: fn(Option<&()>) -> bool = |_| false;
/// let cond_true: fn(Option<&()>) -> bool = |_| true;
/// assert!(!cond_false.and(cond_false).matches_object(None));
/// assert!(!cond_false.and(cond_true).matches_object(None));
/// assert!(!cond_true.and(cond_false).matches_object(None));
/// assert!(cond_true.and(cond_true).matches_object(None));
/// ```
fn and<Other: Condition<K>>(self, other: Other) -> conditions::And<Self, Other>
where
Self: Sized,
{
conditions::And(self, other)
}
/// Returns a `Condition` that holds if either `self` or `other` does
///
/// # Usage
///
/// ```
/// # use kube_runtime::wait::Condition;
/// let cond_false: fn(Option<&()>) -> bool = |_| false;
/// let cond_true: fn(Option<&()>) -> bool = |_| true;
/// assert!(!cond_false.or(cond_false).matches_object(None));
/// assert!(cond_false.or(cond_true).matches_object(None));
/// assert!(cond_true.or(cond_false).matches_object(None));
/// assert!(cond_true.or(cond_true).matches_object(None));
/// ```
fn or<Other: Condition<K>>(self, other: Other) -> conditions::Or<Self, Other>
where
Self: Sized,
{
conditions::Or(self, other)
}
}
impl<K, F: Fn(Option<&K>) -> bool> Condition<K> for F {
fn matches_object(&self, obj: Option<&K>) -> bool {
(self)(obj)
}
}
/// Common conditions to wait for
pub mod conditions {
pub use super::Condition;
use k8s_openapi::{
api::{batch::v1::Job, core::v1::Pod},
apiextensions_apiserver::pkg::apis::apiextensions::v1::CustomResourceDefinition,
};
use kube_client::Resource;
/// An await condition that returns `true` once the object has been deleted.
///
/// An object is considered to be deleted if the object can no longer be found, or if its
/// [`uid`](kube_client::api::ObjectMeta#structfield.uid) changes. This means that an object is considered to be deleted even if we miss
/// the deletion event and the object is recreated in the meantime.
#[must_use]
pub fn is_deleted<K: Resource>(uid: &str) -> impl Condition<K> + '_ {
move |obj: Option<&K>| {
obj.map_or(
// Object is not found, success!
true,
// Object is found, but a changed uid would mean that it was deleted and recreated
|obj| obj.meta().uid.as_deref() != Some(uid),
)
}
}
/// An await condition for `CustomResourceDefinition` that returns `true` once it has been accepted and established
///
/// Note that this condition only guarantees you that you can use `Api<CustomResourceDefinition>` when it is ready.
/// It usually takes extra time for Discovery to notice the custom resource, and there is no condition for this.
#[must_use]
pub fn is_crd_established() -> impl Condition<CustomResourceDefinition> {
|obj: Option<&CustomResourceDefinition>| {
if let Some(o) = obj {
if let Some(s) = &o.status {
if let Some(conds) = &s.conditions {
if let Some(pcond) = conds.iter().find(|c| c.type_ == "Established") {
return pcond.status == "True";
}
}
}
}
false
}
}
/// An await condition for `Pod` that returns `true` once it is running
#[must_use]
pub fn is_pod_running() -> impl Condition<Pod> {
|obj: Option<&Pod>| {
if let Some(pod) = &obj {
if let Some(status) = &pod.status {
if let Some(phase) = &status.phase {
return phase == "Running";
}
}
}
false
}
}
/// An await condition for `Job` that returns `true` once it is completed
#[must_use]
pub fn is_job_completed() -> impl Condition<Job> {
|obj: Option<&Job>| {
if let Some(job) = &obj {
if let Some(s) = &job.status {
if let Some(conds) = &s.conditions {
if let Some(pcond) = conds.iter().find(|c| c.type_ == "Complete") {
return pcond.status == "True";
}
}
}
}
false
}
}
/// See [`Condition::not`]
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub struct Not<A>(pub(super) A);
impl<A: Condition<K>, K> Condition<K> for Not<A> {
fn matches_object(&self, obj: Option<&K>) -> bool {
!self.0.matches_object(obj)
}
}
/// See [`Condition::and`]
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub struct And<A, B>(pub(super) A, pub(super) B);
impl<A, B, K> Condition<K> for And<A, B>
where
A: Condition<K>,
B: Condition<K>,
{
fn matches_object(&self, obj: Option<&K>) -> bool {
self.0.matches_object(obj) && self.1.matches_object(obj)
}
}
/// See [`Condition::or`]
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub struct Or<A, B>(pub(super) A, pub(super) B);
impl<A, B, K> Condition<K> for Or<A, B>
where
A: Condition<K>,
B: Condition<K>,
{
fn matches_object(&self, obj: Option<&K>) -> bool {
self.0.matches_object(obj) || self.1.matches_object(obj)
}
}
}
/// Utilities for deleting objects
pub mod delete {
use super::{await_condition, conditions};
use kube_client::{api::DeleteParams, Api, Resource};
use serde::de::DeserializeOwned;
use std::fmt::Debug;
use thiserror::Error;
#[derive(Debug, Error)]
pub enum Error {
#[error("deleted object has no UID to wait for")]
NoUid,
#[error("failed to delete object: {0}")]
Delete(#[source] kube_client::Error),
#[error("failed to wait for object to be deleted: {0}")]
Await(#[source] super::Error),
}
/// Delete an object, and wait for it to be removed from the Kubernetes API (including waiting for all finalizers to unregister themselves).
///
/// # Errors
///
/// Returns an [`Error`](enum@super::Error) if the object was unable to be deleted, or if the wait was interrupted.
#[allow(clippy::module_name_repetitions)]
pub async fn delete_and_finalize<K: Clone + Debug + Send + DeserializeOwned + Resource + 'static>(
api: Api<K>,
name: &str,
delete_params: &DeleteParams,
) -> Result<(), Error> {
let deleted_obj_uid = api
.delete(name, delete_params)
.await
.map_err(Error::Delete)?
.either(
|mut obj| obj.meta_mut().uid.take(),
|status| status.details.map(|details| details.uid),
)
.ok_or(Error::NoUid)?;
await_condition(api, name, conditions::is_deleted(&deleted_obj_uid))
.await
.map_err(Error::Await)?;
Ok(())
}
}