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Merged
nicklan merged 1 commit into from
Aug 26, 2025
Merged

Defer DNS resolution for TLS server names to improve startup performance #230

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66 changes: 12 additions & 54 deletions src/config/kube.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -17,14 +17,12 @@

use base64::engine::{general_purpose::STANDARD, Engine};

use hickory_resolver::{config::*, Resolver};
use std::collections::BTreeMap;
use std::collections::HashMap;
use std::convert::From;
use std::env;
use std::fs::File;
use std::io::{BufReader, Read};
use std::net::IpAddr;

//use crate::certs::{get_cert, get_cert_from_pem, get_key_from_str, get_private_key};
use super::kubefile::{AuthProvider, ExecProvider};
Expand All @@ -38,7 +36,6 @@ pub struct ClusterConf {
pub server: String,
pub tls_server_name: Option<String>,
pub insecure_skip_tls_verify: bool,
pub custom_dns_mapping: Option<(String, IpAddr)>, // (hostname, resolved_ip)
}

impl ClusterConf {
Expand All @@ -52,22 +49,19 @@ impl ClusterConf {
server,
tls_server_name,
insecure_skip_tls_verify: true,
custom_dns_mapping: None,
}
}

fn new_with_custom_dns(
fn new_secure(
cert: Option<String>,
server: String,
tls_server_name: Option<String>,
custom_dns_mapping: Option<(String, IpAddr)>,
) -> ClusterConf {
ClusterConf {
cert,
server,
tls_server_name,
insecure_skip_tls_verify: false,
custom_dns_mapping,
}
}
}
Expand Down Expand Up @@ -133,19 +127,6 @@ pub struct Config {
pub users: HashMap<String, UserConf>,
}

// Helper function to create custom DNS mapping from server URL and TLS server name
fn create_custom_dns_mapping(server_url: &str, tls_server_name: &str) -> Option<(String, IpAddr)> {
let url = reqwest::Url::parse(server_url).ok()?;
let proxy_host = url.host_str()?;

// Resolve the proxy host to its IP address
let resolver = Resolver::new(ResolverConfig::default(), ResolverOpts::default()).ok()?;
let response = resolver.lookup_ip(proxy_host).ok()?;
let proxy_ip = response.iter().next()?;

Some((tls_server_name.to_string(), proxy_ip))
}

// some utility functions
fn get_full_path(path: String) -> Result<String, ClickError> {
if path.is_empty() {
Expand Down Expand Up @@ -210,18 +191,12 @@ impl Config {
let mut s = String::new();
br.read_to_string(&mut s).expect("Couldn't read cert");

let custom_dns =
cluster.conf.tls_server_name.as_ref().and_then(|tls_name| {
create_custom_dns_mapping(&cluster.conf.server, tls_name)
});

cluster_map.insert(
cluster.name.clone(),
ClusterConf::new_with_custom_dns(
ClusterConf::new_secure(
Some(s),
cluster.conf.server.clone(),
cluster.conf.tls_server_name.clone(),
custom_dns,
),
);
}
Expand All @@ -243,18 +218,12 @@ impl Config {
))
})?;

let custom_dns =
cluster.conf.tls_server_name.as_ref().and_then(|tls_name| {
create_custom_dns_mapping(&cluster.conf.server, tls_name)
});

cluster_map.insert(
cluster.name.clone(),
ClusterConf::new_with_custom_dns(
ClusterConf::new_secure(
Some(cert_pem),
cluster.conf.server.clone(),
cluster.conf.tls_server_name.clone(),
custom_dns,
),
);
}
Expand All @@ -263,31 +232,20 @@ impl Config {
}
},
(None, None) => {
let custom_dns =
cluster.conf.tls_server_name.as_ref().and_then(|tls_name| {
create_custom_dns_mapping(&cluster.conf.server, tls_name)
});

let mut conf = if cluster.conf.skip_tls {
let conf = if cluster.conf.skip_tls {
ClusterConf::new_insecure(
None,
cluster.conf.server.clone(),
cluster.conf.tls_server_name.clone(),
)
} else {
ClusterConf::new_with_custom_dns(
ClusterConf::new_secure(
None,
cluster.conf.server.clone(),
cluster.conf.tls_server_name.clone(),
custom_dns.clone(),
)
};

// For insecure connections, we still want the custom DNS mapping
if cluster.conf.skip_tls && custom_dns.is_some() {
conf.custom_dns_mapping = custom_dns;
}

cluster_map.insert(cluster.name.clone(), conf);
}
}
Expand Down Expand Up @@ -338,11 +296,10 @@ impl Config {

let mut endpoint = reqwest::Url::parse(&cluster.server)?;

// When using custom DNS mapping, we keep the original hostname in the URL
// When using TLS server name, we need to update the endpoint URL to use the TLS server name
// The DNS resolver will handle mapping it to the correct IP
// We also need to ensure we're using the TLS server name for proper hostname
if let Some((tls_hostname, _)) = &cluster.custom_dns_mapping {
endpoint.set_host(Some(tls_hostname))?;
if let Some(ref tls_server_name) = cluster.tls_server_name {
endpoint.set_host(Some(tls_server_name))?;
}

let ca_certs = match &cluster.cert {
Expand Down Expand Up @@ -400,7 +357,8 @@ impl Config {
user.impersonate_user.clone(),
click_conf.connect_timeout_secs,
click_conf.read_timeout_secs,
cluster.custom_dns_mapping.clone(),
cluster.server.clone(),
cluster.tls_server_name.clone(),
)
})
}
Expand Down Expand Up @@ -533,7 +491,7 @@ bW1EDp3zdHSo1TRJ6V6e6bR64eVaH4QwnNOfpSXY
assert!(ctx.is_ok());
let ctx = ctx.unwrap();

// The original server hostname should be preserved when DNS resolution fails
assert!(ctx.endpoint.host_str() == Some("proxy.example.com"));
// When TLS server name is provided, the endpoint should use the TLS server name -- custom resolver will resolve to the correct IP
assert!(ctx.endpoint.host_str() == Some("api.example.com"));
}
}
50 changes: 38 additions & 12 deletions src/k8s.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@

use base64::engine::{general_purpose::STANDARD, Engine};
use bytes::Bytes;
use hickory_resolver::{config::*, Resolver};
use k8s_openapi::{http, List, ListableResource};
use reqwest::blocking::Client;
use reqwest::{Certificate, Identity, Url};
Expand All @@ -34,6 +35,20 @@ use crate::{
error::{ClickErrNo, ClickError},
};

// Helper function to create custom DNS mapping from server URL and TLS server name
// This is called lazily when the client is created
fn create_custom_dns_mapping(server_url: &str, tls_server_name: &str) -> Option<(String, IpAddr)> {
let url = reqwest::Url::parse(server_url).ok()?;
let proxy_host = url.host_str()?;

// Resolve the proxy host to its IP address
let resolver = Resolver::new(ResolverConfig::default(), ResolverOpts::default()).ok()?;
let response = resolver.lookup_ip(proxy_host).ok()?;
let proxy_ip = response.iter().next()?;

Some((tls_server_name.to_string(), proxy_ip))
}

#[derive(Clone)]
pub enum UserAuth {
AuthProvider(Box<AuthProvider>),
Expand Down Expand Up @@ -176,7 +191,8 @@ pub struct Context {
impersonate_user: Option<String>,
connect_timeout_secs: u32,
read_timeout_secs: u32,
custom_dns_mapping: Option<(String, IpAddr)>,
server_url: String,
tls_server_name: Option<String>,
}

impl Context {
Expand All @@ -189,7 +205,8 @@ impl Context {
impersonate_user: Option<String>,
connect_timeout_secs: u32,
read_timeout_secs: u32,
custom_dns_mapping: Option<(String, IpAddr)>,
server_url: String,
tls_server_name: Option<String>,
) -> Context {
let (client, client_auth) = Context::get_client(
&endpoint,
Expand All @@ -198,7 +215,8 @@ impl Context {
None,
connect_timeout_secs,
read_timeout_secs,
custom_dns_mapping.clone(),
&server_url,
&tls_server_name,
);
// have to create a special client for logs until
// https://github.com/seanmonstar/reqwest/issues/1380
Expand All @@ -210,7 +228,8 @@ impl Context {
None,
u32::MAX,
u32::MAX,
custom_dns_mapping.clone(),
&server_url,
&tls_server_name,
);
let client = RefCell::new(client);
let log_client = RefCell::new(log_client);
Expand All @@ -225,29 +244,34 @@ impl Context {
impersonate_user,
connect_timeout_secs,
read_timeout_secs,
custom_dns_mapping,
server_url,
tls_server_name,
}
}

#[allow(clippy::too_many_arguments)]
fn get_client(
endpoint: &Url,
root_cas: Option<Vec<Certificate>>,
auth: Option<UserAuth>,
id: Option<Identity>,
connect_timeout_secs: u32,
read_timeout_secs: u32,
custom_dns_mapping: Option<(String, IpAddr)>,
server_url: &str,
tls_server_name: &Option<String>,
) -> (Client, Option<UserAuth>) {
let host = endpoint.host().unwrap();
let mut client = match host {
Host::Domain(_) => Client::builder().use_rustls_tls(),
_ => Client::builder().use_native_tls(),
};

// Use custom DNS mapping if we have one
if let Some((hostname, ip)) = custom_dns_mapping {
// reqwest's resolve method allows mapping specific hostnames to IP addresses
client = client.resolve(&hostname, SocketAddr::new(ip, 443));
// Create custom DNS mapping if we have a TLS server name
if let Some(tls_name) = tls_server_name {
if let Some((hostname, ip)) = create_custom_dns_mapping(server_url, tls_name) {
// reqwest's resolve method allows mapping specific hostnames to IP addresses
client = client.resolve(&hostname, SocketAddr::new(ip, 443));
}
}
let client = match root_cas {
Some(cas) => {
Expand Down Expand Up @@ -306,7 +330,8 @@ impl Context {
Some(id.clone()),
self.connect_timeout_secs,
self.read_timeout_secs,
self.custom_dns_mapping.clone(),
&self.server_url,
&self.tls_server_name,
);
let (new_log_client, _) = Context::get_client(
&self.endpoint,
Expand All @@ -315,7 +340,8 @@ impl Context {
Some(id),
u32::MAX,
u32::MAX,
self.custom_dns_mapping.clone(),
&self.server_url,
&self.tls_server_name,
);
*self.client.borrow_mut() = new_client;
*self.log_client.borrow_mut() = new_log_client;
Expand Down
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