Crate kube

Kube is an umbrella-crate for interacting with Kubernetes in Rust.

Overview

Kube contains a Kubernetes client, a controller runtime, a custom resource derive, and various tooling required for building applications or controllers that interact with Kubernetes.

The main modules are:

• client with the Kubernetes Client and its layers
• config for cluster Config
• api with the generic Kubernetes Api
• derive with the CustomResource / Resource derive for building controllers types
• runtime with a Controller / watcher / reflector / Store
• core with generics from apimachinery

You can use each of these as you need with the help of the exported features.

Using the Client

use futures::{StreamExt, TryStreamExt};
use kube::{Client, api::{Api, ResourceExt, ListParams, PostParams}};
use k8s_openapi::api::core::v1::Pod;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Infer the runtime environment and try to create a Kubernetes Client
    let client = Client::try_default().await?;

    // Read pods in the configured namespace into the typed interface from k8s-openapi
    let pods: Api<Pod> = Api::default_namespaced(client);
    for p in pods.list(&ListParams::default()).await? {
        println!("found pod {}", p.name_any());
    }
    Ok(())
}

For details, see:

• Client for the extensible Kubernetes client
• Api for the generic api methods available on Kubernetes resources
• k8s-openapi for documentation about the generated Kubernetes types

Using the Runtime with the Derive macro

use schemars::JsonSchema;
use serde::{Deserialize, Serialize};
use serde_json::json;
use futures::{StreamExt, TryStreamExt};
use k8s_openapi::apiextensions_apiserver::pkg::apis::apiextensions::v1::CustomResourceDefinition;
use kube::{
    api::{Api, DeleteParams, PatchParams, Patch, ResourceExt},
    core::CustomResourceExt,
    Client, CustomResource,
    runtime::{watcher, WatchStreamExt, wait::{conditions, await_condition}},
};

// Our custom resource
#[derive(CustomResource, Deserialize, Serialize, Clone, Debug, JsonSchema)]
#[kube(group = "clux.dev", version = "v1", kind = "Foo", namespaced)]
pub struct FooSpec {
    info: String,
    #[schemars(length(min = 3))]
    name: String,
    replicas: i32,
}

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let client = Client::try_default().await?;
    let crds: Api<CustomResourceDefinition> = Api::all(client.clone());

    // Apply the CRD so users can create Foo instances in Kubernetes
    crds.patch("foos.clux.dev",
        &PatchParams::apply("my_manager"),
        &Patch::Apply(Foo::crd())
    ).await?;

    // Wait for the CRD to be ready
    tokio::time::timeout(
        std::time::Duration::from_secs(10),
        await_condition(crds, "foos.clux.dev", conditions::is_crd_established())
    ).await?;

    // Watch for changes to foos in the configured namespace
    let foos: Api<Foo> = Api::default_namespaced(client.clone());
    let wc = watcher::Config::default();
    let mut apply_stream = watcher(foos, wc).applied_objects().boxed();
    while let Some(f) = apply_stream.try_next().await? {
        println!("saw apply to {}", f.name_any());
    }
    Ok(())
}

For details, see:

• CustomResource for documentation how to configure custom resources
• runtime::watcher for how to long-running watches work and why you want to use this over Api::watch
• runtime for abstractions that help with more complicated Kubernetes application

Examples

A large list of complete, runnable examples with explainations are available in the examples folder.

Modules

• apiclient
  API helpers for structured interaction with the Kubernetes API
• clientclient
  API client for interacting with the Kubernetes API
• configconfig
  Kubernetes configuration objects.
• core
  Types and traits necessary for interacting with the Kubernetes API
• discoveryclient
  High-level utilities for runtime API discovery.
• errorconfig or client
  Error handling and error types
• prelude
  A prelude for kube. Reduces the number of duplicated imports.
• runtimeruntime
  Common components for building Kubernetes operators

Structs

• Apiclient
  The generic Api abstraction
• Clientclient
  Client for connecting with a Kubernetes cluster.
• Configconfig
  Configuration object for accessing a Kuernetes cluster
• Discoveryclient
  A caching client for running API discovery against the Kubernetes API.

Enums

• Errorconfig or client
  Possible errors from the Client

Traits

• CustomResourceExt
  Extension trait that is implemented by kube-derive
• Resource
  An accessor trait for a kubernetes Resource.
• ResourceExt
  Helper methods for resources.

Type Aliases

• Resultconfig or client
  Convient alias for Result<T, Error>

Derive Macros

• CustomResourcederive
  A custom derive for kubernetes custom resource definitions.
• Resourcederive
  A custom derive for inheriting Resource impl for the type.