Crate kube

Expand description

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 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());
    }
    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 validator::Validate;
use futures::{StreamExt, TryStreamExt};
use k8s_openapi::apiextensions_apiserver::pkg::apis::apiextensions::v1::CustomResourceDefinition;
use kube::{
    api::{Api, DeleteParams, ListParams, PatchParams, Patch, ResourceExt},
    core::CustomResourceExt,
    Client, CustomResource,
    runtime::{watcher, utils::try_flatten_applied, wait::{conditions, await_condition}},
};

// Our custom resource
#[derive(CustomResource, Deserialize, Serialize, Clone, Debug, Validate, JsonSchema)]
#[kube(group = "clux.dev", version = "v1", kind = "Foo", namespaced)]
pub struct FooSpec {
    info: String,
    #[validate(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 lp = ListParams::default();
    let mut apply_stream = try_flatten_applied(watcher(foos, lp)).boxed();
    while let Some(f) = apply_stream.try_next().await? {
        println!("saw apply to {}", f.name());
    }
    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