Signalling the postgres server when the leader changes, but does not become this node

pmeunier

Jan 18, 2022, 11:35 PM

UEGA35KU63HPNZLXVR5CS2BNMCVOV7HOBTDR4K6YZSPDFWXIKKZQC

Dependencies

• [2] FIIWK33F Fixing lock issues
• [3] ENEREHTW Restart and rewind the server during failover (requires policykit)
• [4] NPSWSVZN Init
• [5] 6Z6PYXTS Testing and debugging

Change contents

• replacement in src/main.rs at line 261
  [2.2226]→[2.2226:2287](∅→∅)
  − rewind(&path, port, &db_name, leader).await;
  [2.2226]

  [2.2287]
  + rewind(&path, port, &db_name, leader, &password).await;

  + } else {

  + reload(&path).await;
• edit in src/main.rs at line 265
  [2.2301]

  [3.3173]
  + } else {

  + reload(&path).await;
• replacement in src/main.rs at line 287
  [3.3348]→[3.3348:3418](∅→∅),[3.3418]→[2.2501:2526](∅→∅)
  − async fn rewind(path: &str, port: u16, db_name: &str, leader: &str) {

  − debug!("rewinding");
  [3.3348]

  [3.3418]
  + async fn reload(path: &str) {

  + debug!("reload");
• replacement in src/main.rs at line 290
  [3.3451]→[2.2527:2567](∅→∅),[2.2567]→[3.3481:3524](∅→∅),[3.3481]→[3.3481:3524](∅→∅)
  − let out = Command::new("systemctl")

  − .args(["stop", "postgresql-repl"])
  [3.3451]

  [3.3524]
  + let out = Command::new("pg_ctl")

  + .args(["reload", "-D", path])
• edit in src/main.rs at line 298
  [2.2702]

  [2.2702]
  + }

  +

  + async fn rewind(path: &str, port: u16, db_name: &str, leader: &str, password: &str) {

  + debug!("rewinding");

  + use std::io::Write;

  + use tokio::process::Command;
• edit in src/main.rs at line 306
  [2.2752]

  [2.2752]
  + let out = Command::new("systemctl")

  + .args(["stop", "postgresql-repl"])

  + .output()

  + .await

  + .expect("failed to execute process");

  + std::io::stdout().write_all(&out.stdout).unwrap();

  + std::io::stderr().write_all(&out.stderr).unwrap();

  + success = out.status.success();

  + tokio::time::sleep(std::time::Duration::from_secs(1)).await;

  + }

  + let mut success = false;

  + while !success {
• replacement in src/main.rs at line 338
  [2.3449]→[2.3449:3489](∅→∅),[2.3489]→[3.3989:4112](∅→∅),[3.3989]→[3.3989:4112](∅→∅),[3.4112]→[2.3490:3600](∅→∅)
  − let out = Command::new("systemctl")

  − .args(["start", "postgresql-repl"])

  − .output()

  − .await

  − .expect("failed to execute process");

  − std::io::stdout().write_all(&out.stdout).unwrap();

  − std::io::stderr().write_all(&out.stderr).unwrap();
  [2.3449]

  [3.4112]
  +

  + std::fs::write(

  + std::path::Path::new(path).join("postgresql.auto.conf"),

  + format!(

  + "primary_conninfo = 'host={} port=5432 user=replication password={}'",

  + leader, password,

  + ),

  + )

  + .unwrap();

  +

  + let mut success = false;

  + while !success {

  + let out = Command::new("systemctl")

  + .args(["start", "postgresql-repl"])

  + .output()

  + .await

  + .expect("failed to execute process");

  + std::io::stdout().write_all(&out.stdout).unwrap();

  + std::io::stderr().write_all(&out.stderr).unwrap();

  + success = out.status.success();

  + tokio::time::sleep(std::time::Duration::from_secs(1)).await;

  + }