Use the local kubelet's cluster domain, rather than a random one

Author: nightkr

crates/stackable-operator/src/utils/cluster_info.rs

@@ -18,25 +18,35 @@ pub struct KubernetesClusterInfo {
 #[derive(clap::Parser, Debug, Default, PartialEq, Eq)]
 pub struct KubernetesClusterInfoOpts {
     /// Kubernetes cluster domain, usually this is `cluster.local`.
-    // We are not using a default value here, as operators will probably do an more advanced
-    // auto-detection of the cluster domain in case it is not specified in the future.
+    // We are not using a default value here, as we query the cluster if it is not specified.
     #[arg(long, env)]
     pub kubernetes_cluster_domain: Option<DomainName>,
+
+    /// Name of the Kubernetes Node that the operator is running on.
+    #[arg(long, env)]
+    pub kubernetes_node_name: String,
 }
 
 impl KubernetesClusterInfo {
     pub async fn new(
         client: &Client,
         cluster_info_opts: &KubernetesClusterInfoOpts,
     ) -> Result<Self, Error> {
-        let cluster_domain = match &cluster_info_opts.kubernetes_cluster_domain {
-            Some(cluster_domain) => {
+        let cluster_domain = match cluster_info_opts {
+            KubernetesClusterInfoOpts {
+                kubernetes_cluster_domain: Some(cluster_domain),
+                ..
+            } => {
                 tracing::info!(%cluster_domain, "Using configured Kubernetes cluster domain");
 
                 cluster_domain.clone()
             }
-            None => {
-                let kubelet_config = kubelet::KubeletConfig::fetch(client)
+            KubernetesClusterInfoOpts {
+                kubernetes_node_name: node_name,
+                ..
+            } => {
+                tracing::info!(%node_name, "Fetching Kubernetes cluster domain from the local kubelet");
+                let kubelet_config = kubelet::KubeletConfig::fetch(client, node_name)
                     .await
                     .context(KubeletConfigSnafu)?;
 

crates/stackable-operator/src/utils/kubelet.rs

@@ -1,20 +1,12 @@
 use http;
-use k8s_openapi::api::core::v1::Node;
-use kube::{
-    Api,
-    api::{ListParams, ResourceExt},
-    client::Client,
-};
+use kube::client::Client;
 use serde::Deserialize;
-use snafu::{OptionExt, ResultExt, Snafu};
+use snafu::{ResultExt, Snafu};
 
 use crate::commons::networking::DomainName;
 
 #[derive(Debug, Snafu)]
 pub enum Error {
-    #[snafu(display("failed to list nodes"))]
-    ListNodes { source: kube::Error },
-
     #[snafu(display("failed to build request for url path \"{url_path}\""))]
     BuildConfigzRequest {
         source: http::Error,
@@ -29,11 +21,6 @@ pub enum Error {
 
     #[snafu(display("failed to deserialize kubelet config JSON"))]
     KubeletConfigJson { source: serde_json::Error },
-
-    #[snafu(display(
-        "empty Kubernetes nodes list. At least one node is required to fetch the cluster domain from the kubelet config"
-    ))]
-    EmptyKubernetesNodesList,
 }
 
 #[derive(Debug, Deserialize)]
@@ -49,16 +36,8 @@ pub struct KubeletConfig {
 }
 
 impl KubeletConfig {
-    /// Fetches the kubelet configuration from the "first" node in the Kubernetes cluster.
-    pub async fn fetch(client: &Client) -> Result<Self, Error> {
-        let api: Api<Node> = Api::all(client.clone());
-        let nodes = api
-            .list(&ListParams::default())
-            .await
-            .context(ListNodesSnafu)?;
-        let node = nodes.iter().next().context(EmptyKubernetesNodesListSnafu)?;
-        let node_name = node.name_any();
-
+    /// Fetches the kubelet configuration from the specified node in the Kubernetes cluster.
+    pub async fn fetch(client: &Client, node_name: &str) -> Result<Self, Error> {
         let url_path = format!("/api/v1/nodes/{node_name}/proxy/configz");
         let req = http::Request::get(url_path.clone())
             .body(Default::default())