feat(compute_ctl): Always set application_name (#9934)

## Problem

It was not always possible to judge what exactly some `cloud_admin`
connections were doing because we didn't consistently set
`application_name` everywhere.

## Summary of changes

Unify the way we connect to Postgres:
1. Switch to building configs everywhere
2. Always set `application_name` and make naming consistent

Follow-up for #9919
Part of neondatabase/cloud#20948

compute_tools/src/bin/compute_ctl.rs

@@ -37,6 +37,7 @@ use std::collections::HashMap;
 use std::fs::File;
 use std::path::Path;
 use std::process::exit;
+use std::str::FromStr;
 use std::sync::atomic::Ordering;
 use std::sync::{mpsc, Arc, Condvar, Mutex, RwLock};
 use std::{thread, time::Duration};
@@ -322,8 +323,15 @@ fn wait_spec(
     } else {
         spec_set = false;
     }
+    let connstr = Url::parse(connstr).context("cannot parse connstr as a URL")?;
+    let conn_conf = postgres::config::Config::from_str(connstr.as_str())
+        .context("cannot build postgres config from connstr")?;
+    let tokio_conn_conf = tokio_postgres::config::Config::from_str(connstr.as_str())
+        .context("cannot build tokio postgres config from connstr")?;
     let compute_node = ComputeNode {
-        connstr: Url::parse(connstr).context("cannot parse connstr as a URL")?,
+        connstr,
+        conn_conf,
+        tokio_conn_conf,
         pgdata: pgdata.to_string(),
         pgbin: pgbin.to_string(),
         pgversion: get_pg_version_string(pgbin),

compute_tools/src/catalog.rs

@@ -6,7 +6,6 @@ use tokio::{
     process::Command,
     spawn,
 };
-use tokio_postgres::connect;
 use tokio_stream::{self as stream, StreamExt};
 use tokio_util::codec::{BytesCodec, FramedRead};
 use tracing::warn;
@@ -16,10 +15,8 @@ use crate::pg_helpers::{get_existing_dbs_async, get_existing_roles_async, postgr
 use compute_api::responses::CatalogObjects;
 
 pub async fn get_dbs_and_roles(compute: &Arc<ComputeNode>) -> anyhow::Result<CatalogObjects> {
-    let connstr = compute.connstr.clone();
-
-    let (client, connection): (tokio_postgres::Client, _) =
-        connect(connstr.as_str(), NoTls).await?;
+    let conf = compute.get_tokio_conn_conf(Some("compute_ctl:get_dbs_and_roles"));
+    let (client, connection): (tokio_postgres::Client, _) = conf.connect(NoTls).await?;
 
     spawn(async move {
         if let Err(e) = connection.await {

compute_tools/src/checker.rs

@@ -9,7 +9,8 @@ use crate::compute::ComputeNode;
 #[instrument(skip_all)]
 pub async fn check_writability(compute: &ComputeNode) -> Result<()> {
     // Connect to the database.
-    let (client, connection) = tokio_postgres::connect(compute.connstr.as_str(), NoTls).await?;
+    let conf = compute.get_tokio_conn_conf(Some("compute_ctl:availability_checker"));
+    let (client, connection) = conf.connect(NoTls).await?;
     if client.is_closed() {
         return Err(anyhow!("connection to postgres closed"));
     }

compute_tools/src/compute.rs

@@ -20,8 +20,9 @@ use futures::future::join_all;
 use futures::stream::FuturesUnordered;
 use futures::StreamExt;
 use nix::unistd::Pid;
+use postgres;
 use postgres::error::SqlState;
-use postgres::{Client, NoTls};
+use postgres::NoTls;
 use tracing::{debug, error, info, instrument, warn};
 use utils::id::{TenantId, TimelineId};
 use utils::lsn::Lsn;
@@ -58,6 +59,10 @@ pub static PG_PID: AtomicU32 = AtomicU32::new(0);
 pub struct ComputeNode {
     // Url type maintains proper escaping
     pub connstr: url::Url,
+    // We connect to Postgres from many different places, so build configs once
+    // and reuse them where needed.
+    pub conn_conf: postgres::config::Config,
+    pub tokio_conn_conf: tokio_postgres::config::Config,
     pub pgdata: String,
     pub pgbin: String,
     pub pgversion: String,
@@ -800,10 +805,10 @@ impl ComputeNode {
     /// version. In the future, it may upgrade all 3rd-party extensions.
     #[instrument(skip_all)]
     pub fn post_apply_config(&self) -> Result<()> {
-        let connstr = self.connstr.clone();
+        let conf = self.get_conn_conf(Some("compute_ctl:post_apply_config"));
         thread::spawn(move || {
             let func = || {
-                let mut client = Client::connect(connstr.as_str(), NoTls)?;
+                let mut client = conf.connect(NoTls)?;
                 handle_neon_extension_upgrade(&mut client)
                     .context("handle_neon_extension_upgrade")?;
                 Ok::<_, anyhow::Error>(())
@@ -815,12 +820,27 @@ impl ComputeNode {
         Ok(())
     }
 
+    pub fn get_conn_conf(&self, application_name: Option<&str>) -> postgres::Config {
+        let mut conf = self.conn_conf.clone();
+        if let Some(application_name) = application_name {
+            conf.application_name(application_name);
+        }
+        conf
+    }
+
+    pub fn get_tokio_conn_conf(&self, application_name: Option<&str>) -> tokio_postgres::Config {
+        let mut conf = self.tokio_conn_conf.clone();
+        if let Some(application_name) = application_name {
+            conf.application_name(application_name);
+        }
+        conf
+    }
+
     async fn get_maintenance_client(
         conf: &tokio_postgres::Config,
     ) -> Result<tokio_postgres::Client> {
         let mut conf = conf.clone();
-
-        conf.application_name("apply_config");
+        conf.application_name("compute_ctl:apply_config");
 
         let (client, conn) = match conf.connect(NoTls).await {
             // If connection fails, it may be the old node with `zenith_admin` superuser.
@@ -837,6 +857,7 @@ impl ComputeNode {
                         e
                     );
                     let mut zenith_admin_conf = postgres::config::Config::from(conf.clone());
+                    zenith_admin_conf.application_name("compute_ctl:apply_config");
                     zenith_admin_conf.user("zenith_admin");
 
                     let mut client =
@@ -1134,8 +1155,7 @@ impl ComputeNode {
     /// Do initial configuration of the already started Postgres.
     #[instrument(skip_all)]
     pub fn apply_config(&self, compute_state: &ComputeState) -> Result<()> {
-        let mut conf = tokio_postgres::Config::from_str(self.connstr.as_str()).unwrap();
-        conf.application_name("apply_config");
+        let conf = self.get_tokio_conn_conf(Some("compute_ctl:apply_config"));
 
         let conf = Arc::new(conf);
         let spec = Arc::new(
@@ -1161,7 +1181,7 @@ impl ComputeNode {
         thread::spawn(move || {
             let conf = conf.as_ref().clone();
             let mut conf = postgres::config::Config::from(conf);
-            conf.application_name("migrations");
+            conf.application_name("compute_ctl:migrations");
 
             let mut client = conf.connect(NoTls)?;
             handle_migrations(&mut client).context("apply_config handle_migrations")
@@ -1369,9 +1389,9 @@ impl ComputeNode {
             }
             self.post_apply_config()?;
 
-            let connstr = self.connstr.clone();
+            let conf = self.get_conn_conf(None);
             thread::spawn(move || {
-                let res = get_installed_extensions(&connstr);
+                let res = get_installed_extensions(conf);
                 match res {
                     Ok(extensions) => {
                         info!(
@@ -1510,7 +1530,8 @@ impl ComputeNode {
     /// Select `pg_stat_statements` data and return it as a stringified JSON
     pub async fn collect_insights(&self) -> String {
         let mut result_rows: Vec<String> = Vec::new();
-        let connect_result = tokio_postgres::connect(self.connstr.as_str(), NoTls).await;
+        let conf = self.get_tokio_conn_conf(Some("compute_ctl:collect_insights"));
+        let connect_result = conf.connect(NoTls).await;
         let (client, connection) = connect_result.unwrap();
         tokio::spawn(async move {
             if let Err(e) = connection.await {
@@ -1636,10 +1657,9 @@ LIMIT 100",
         privileges: &[Privilege],
         role_name: &PgIdent,
     ) -> Result<()> {
-        use tokio_postgres::config::Config;
         use tokio_postgres::NoTls;
 
-        let mut conf = Config::from_str(self.connstr.as_str()).unwrap();
+        let mut conf = self.get_tokio_conn_conf(Some("compute_ctl:set_role_grants"));
         conf.dbname(db_name);
 
         let (db_client, conn) = conf
@@ -1676,10 +1696,9 @@ LIMIT 100",
         db_name: &PgIdent,
         ext_version: ExtVersion,
     ) -> Result<ExtVersion> {
-        use tokio_postgres::config::Config;
         use tokio_postgres::NoTls;
 
-        let mut conf = Config::from_str(self.connstr.as_str()).unwrap();
+        let mut conf = self.get_tokio_conn_conf(Some("compute_ctl:install_extension"));
         conf.dbname(db_name);
 
         let (db_client, conn) = conf

compute_tools/src/http/api.rs

@@ -295,12 +295,11 @@ async fn routes(req: Request<Body>, compute: &Arc<ComputeNode>) -> Response<Body
                 return Response::new(Body::from(msg));
             }
 
-            let connstr = compute.connstr.clone();
-            let res = task::spawn_blocking(move || {
-                installed_extensions::get_installed_extensions(&connstr)
-            })
-            .await
-            .unwrap();
+            let conf = compute.get_conn_conf(None);
+            let res =
+                task::spawn_blocking(move || installed_extensions::get_installed_extensions(conf))
+                    .await
+                    .unwrap();
 
             match res {
                 Ok(res) => render_json(Body::from(serde_json::to_string(&res).unwrap())),

compute_tools/src/installed_extensions.rs

@@ -10,8 +10,6 @@ use metrics::core::Collector;
 use metrics::{register_uint_gauge_vec, UIntGaugeVec};
 use once_cell::sync::Lazy;
 
-use crate::pg_helpers::postgres_conf_for_db;
-
 /// We don't reuse get_existing_dbs() just for code clarity
 /// and to make database listing query here more explicit.
 ///
@@ -41,14 +39,16 @@ fn list_dbs(client: &mut Client) -> Result<Vec<String>> {
 ///
 /// Same extension can be installed in multiple databases with different versions,
 /// we only keep the highest and lowest version across all databases.
-pub fn get_installed_extensions(connstr: &url::Url) -> Result<InstalledExtensions> {
-    let mut client = Client::connect(connstr.as_str(), NoTls)?;
+pub fn get_installed_extensions(mut conf: postgres::config::Config) -> Result<InstalledExtensions> {
+    conf.application_name("compute_ctl:get_installed_extensions");
+    let mut client = conf.connect(NoTls)?;
+
     let databases: Vec<String> = list_dbs(&mut client)?;
 
     let mut extensions_map: HashMap<String, InstalledExtension> = HashMap::new();
     for db in databases.iter() {
-        let config = postgres_conf_for_db(connstr, db)?;
-        let mut db_client = config.connect(NoTls)?;
+        conf.dbname(db);
+        let mut db_client = conf.connect(NoTls)?;
         let extensions: Vec<(String, String)> = db_client
             .query(
                 "SELECT extname, extversion FROM pg_catalog.pg_extension;",
@@ -82,7 +82,7 @@ pub fn get_installed_extensions(connstr: &url::Url) -> Result<InstalledExtension
     }
 
     let res = InstalledExtensions {
-        extensions: extensions_map.values().cloned().collect(),
+        extensions: extensions_map.into_values().collect(),
     };
 
     Ok(res)

compute_tools/src/monitor.rs

@@ -17,19 +17,16 @@ const MONITOR_CHECK_INTERVAL: Duration = Duration::from_millis(500);
 // should be handled gracefully.
 fn watch_compute_activity(compute: &ComputeNode) {
     // Suppose that `connstr` doesn't change
-    let mut connstr = compute.connstr.clone();
-    connstr
-        .query_pairs_mut()
-        .append_pair("application_name", "compute_activity_monitor");
-    let connstr = connstr.as_str();
+    let connstr = compute.connstr.clone();
+    let conf = compute.get_conn_conf(Some("compute_ctl:activity_monitor"));
 
     // During startup and configuration we connect to every Postgres database,
     // but we don't want to count this as some user activity. So wait until
     // the compute fully started before monitoring activity.
     wait_for_postgres_start(compute);
 
     // Define `client` outside of the loop to reuse existing connection if it's active.
-    let mut client = Client::connect(connstr, NoTls);
+    let mut client = conf.connect(NoTls);
 
     let mut sleep = false;
     let mut prev_active_time: Option<f64> = None;
@@ -57,7 +54,7 @@ fn watch_compute_activity(compute: &ComputeNode) {
                     info!("connection to Postgres is closed, trying to reconnect");
 
                     // Connection is closed, reconnect and try again.
-                    client = Client::connect(connstr, NoTls);
+                    client = conf.connect(NoTls);
                     continue;
                 }
 
@@ -196,7 +193,7 @@ fn watch_compute_activity(compute: &ComputeNode) {
                 debug!("could not connect to Postgres: {}, retrying", e);
 
                 // Establish a new connection and try again.
-                client = Client::connect(connstr, NoTls);
+                client = conf.connect(NoTls);
             }
         }
     }