kubert 0.25.0

//! Utilities for configuring a [`kube_client::Client`] from the command line
pub use kube_client::*;
use std::path::PathBuf;
use thiserror::Error;

#[cfg(feature = "prometheus-client")]
mod metrics;
mod timeouts;

#[cfg(feature = "prometheus-client")]
pub use self::metrics::ClientMetricsFamilies;
pub use self::timeouts::ResponseHeadersTimeout;

/// Configures a Kubernetes client
#[derive(Clone, Debug, Default)]
#[cfg_attr(docsrs, doc(cfg(feature = "client")))]
#[cfg_attr(feature = "clap", derive(clap::Parser))]
pub struct ClientArgs {
    /// The name of the kubeconfig cluster to use
    #[cfg_attr(feature = "clap", clap(long))]
    pub cluster: Option<String>,

    /// The name of the kubeconfig context to use
    #[cfg_attr(feature = "clap", clap(long))]
    pub context: Option<String>,

    /// The name of the kubeconfig user to use
    #[cfg_attr(feature = "clap", clap(long))]
    pub user: Option<String>,

    /// The path to the kubeconfig file to use
    #[cfg_attr(feature = "clap", clap(long))]
    pub kubeconfig: Option<PathBuf>,

    /// Username to impersonate for Kubernetes operations
    #[cfg_attr(feature = "clap", clap(long = "as"))]
    pub impersonate_user: Option<String>,

    /// Group to impersonate for Kubernetes operations
    #[cfg_attr(feature = "clap", clap(long = "as-group"))]
    pub impersonate_group: Option<String>,

    /// The timeout for response headers from the Kubernetes API.
    #[cfg_attr(feature = "clap", clap(
        long = "kube-api-response-headers-timeout",
        default_value_t = ResponseHeadersTimeout::default(),
    ))]
    pub response_headers_timeout: ResponseHeadersTimeout,
}

/// A builder for a Kubernetes client.
#[cfg_attr(docsrs, doc(cfg(feature = "client")))]
pub struct ClientBuilder {
    args: ClientArgs,
    #[cfg(feature = "prometheus-client")]
    metrics_families: Option<ClientMetricsFamilies>,
}

/// Indicates an error occurred while configuring the Kubernetes client
#[derive(Debug, Error)]
#[cfg_attr(docsrs, doc(cfg(feature = "client")))]
#[non_exhaustive]
pub enum ConfigError {
    /// Indicates that the kubeconfig file could not be read
    #[error(transparent)]
    Kubeconfig(#[from] config::KubeconfigError),

    /// Indicates that the in-cluster configuration could not be read
    #[error(transparent)]
    InCluster(#[from] config::InClusterError),

    /// Indicates that the client could not be initialized
    #[error(transparent)]
    Client(#[from] Error),
}

impl ClientArgs {
    /// Initializes a Kubernetes client
    ///
    /// This will respect the `$KUBECONFIG` environment variable, but otherwise default to
    /// `~/.kube/config`. The _current-context_ is used unless `context` is set.
    ///
    /// This is basically equivalent to using `kube_client::Client::try_default`, except that it
    /// supports kubeconfig configuration from the command-line.
    pub async fn try_client(self) -> Result<Client, ConfigError> {
        ClientBuilder::from_args(self).build().await
    }

    /// Indicates whether the command-line arguments attempt to customize the Kubernetes
    /// configuration.
    fn is_customized(&self) -> bool {
        self.context.is_some()
            || self.cluster.is_some()
            || self.user.is_some()
            || self.impersonate_user.is_some()
            || self.impersonate_group.is_some()
            || self.kubeconfig.is_some()
    }

    /// Loads a local config if available, falling back to in-cluster config if
    /// client args have not been specified.
    async fn load_config(&self) -> Result<Config, ConfigError> {
        match self.load_local_config().await {
            Ok(config) => Ok(config),
            Err(e) if self.is_customized() => Err(e),
            Err(_) => Config::incluster().map_err(Into::into),
        }
    }

    /// Loads a local (i.e. not in-cluster) Kubernetes client configuration
    ///
    /// First, the `--kubeconfig` argument is used. If that is not set, the `$KUBECONFIG`
    /// environment variable is used. If that is not set, the `~/.kube/config` file is used.
    async fn load_local_config(&self) -> Result<Config, ConfigError> {
        let options = config::KubeConfigOptions {
            context: self.context.clone(),
            cluster: self.cluster.clone(),
            user: self.user.clone(),
        };

        let mut kubeconfig = match &self.kubeconfig {
            Some(path) => config::Kubeconfig::read_from(path.as_path())?,
            None => config::Kubeconfig::read()?,
        };

        if let Some(user) = &self.impersonate_user {
            for auth in kubeconfig.auth_infos.iter_mut() {
                if let Some(ai) = auth.auth_info.as_mut() {
                    ai.impersonate = Some(user.clone());
                }
            }
        }

        if let Some(group) = &self.impersonate_group {
            for auth in kubeconfig.auth_infos.iter_mut() {
                if let Some(ai) = auth.auth_info.as_mut() {
                    ai.impersonate_groups = Some(vec![group.clone()]);
                }
            }
        }

        Config::from_custom_kubeconfig(kubeconfig, &options)
            .await
            .map_err(Into::into)
    }
}

impl ClientBuilder {
    /// Creates a new client builder from the given command-line arguments.
    pub fn from_args(args: ClientArgs) -> Self {
        Self {
            args,
            #[cfg(feature = "prometheus-client")]
            metrics_families: None,
        }
    }

    #[cfg(feature = "prometheus-client")]
    #[cfg_attr(
        docsrs,
        doc(cfg(all(features = "client", feature = "prometheus-client")))
    )]
    /// Adds registered Prometheus metrics to the client.
    pub fn with_metrics(mut self, metrics: ClientMetricsFamilies) -> Self {
        self.metrics_families = Some(metrics);
        self
    }

    /// Builds the Kubernetes client.
    pub async fn build(self) -> Result<Client, ConfigError> {
        let config = self.args.load_config().await?;

        #[cfg(feature = "prometheus-client")]
        let metrics = self
            .metrics_families
            .map_or_else(Default::default, |m| m.metrics(&config));

        let cb = kube_client::client::ClientBuilder::try_from(config)?
            .with_layer(&timeouts::layer(self.args.response_headers_timeout));

        #[cfg(feature = "prometheus-client")]
        let cb = cb.with_layer(&metrics::layer(metrics));

        Ok(cb.build())
    }
}

// Used by middlewares, e.g. timeouts.
mod svc {
    pub use tower::{layer::layer_fn, layer::Layer, Service};

    pub type BoxService = tower::util::BoxService<Request, Response, BoxError>;
    pub type Request = hyper::Request<kube_client::client::Body>;
    pub type Response = hyper::Response<BoxBody>;
    pub type BoxBody =
        Box<dyn hyper::body::Body<Data = bytes::Bytes, Error = BoxError> + Send + Unpin>;
    pub type BoxError = tower::BoxError;
    pub type BoxFuture = futures_util::future::BoxFuture<'static, Result<Response, BoxError>>;
}