add pgbench-tuned wrapper command

It wraps the host it should target and the number of jobs (-j) is tuned according to the PostgREST pool size.

Author: steve-chavez

nixops.nix

@@ -258,7 +258,16 @@ in {
  client = {nodes, resources, ...}: {
  environment.systemPackages = [
  pkgs.k6
- pkgs.postgresql_12 # only used for getting pgbench, no postgresql is started here
+ (pkgs.writeShellScriptBin "pgbench-tuned"
+ ''
+ set -euo pipefail
+
+ ${pkgs.postgresql_12}/bin/pgbench postgres -U postgres \
+ -h ${if env.withSeparatePg then "pg" else "pgrst"} \
+ -T 30 --no-vacuum \
+ --jobs ${builtins.toString (builtins.getAttr nodes.pgrst.config.deployment.ec2.instanceType (import ./postgrest/tuning.nix))} \
+ $@
+ '')
  ];
  deployment = {
  targetEnv = "ec2";

shell.nix

@@ -55,9 +55,9 @@ let
  set -euo pipefail
 
  echo -e "\nRunning pgbench with $1 clients"
- host=$([ "$PGRSTBENCH_SEPARATE_PG" = "true" ] && echo "pg" || echo "pgrst")
  # uses the full cores of the instance and prepared statements
- nixops ssh -d ${prefix} client pgbench postgres -h "$host" -U postgres -j 16 -T 30 -c $1 --no-vacuum -f - < $2 || true
+ # || true is added because the command might fail on lower instances with FATAL: sorry, too many clients already
+ nixops ssh -d ${prefix} client pgbench-tuned -c $1 -f - < $2 || true
  '';
  clientPgBenchVaried =
  pkgs.writeShellScriptBin (prefix + "-pgbench-vary-clients")