j4rs

Hardening a host for autonomous coding agents

A runbook from moving an unattended coding-agent setup (an orchestrator that picks issues from a tracker and runs a coding agent on each, opening PRs) from "agents run as a user on a VM" to "each agent works in its own disposable dev machine and holds no secrets". It is written from a real migration of one VM: an orchestrator (Symphony-style), the Codex CLI as the agent, a Rails + React monorepo, GitHub, and a Linear tracker. The names are ours; the shape applies to any agent that runs shell commands.

Everything below was done in small, reviewed steps, each one tried on a throwaway workspace before it went live, and each change to a trust boundary got an adversarial review and a re-review of its fixes. The order matters more than any single setting.

1. Threat model

Treat the agent as untrusted code that runs with whatever you give it. It reads issue text, PR comments, web pages and repo files, any of which can car

nateberkopec

#!/usr/bin/env ruby
# frozen_string_literal: true

require "bundler"
require "cgi"
require "json"
require "net/http"
require "optparse"
require "thread"
require "uri"

jjb

For years, people have been using jemalloc with ruby. There were various benchmarks and discussions. Legend had it that Jemalloc 5 didn't work as well as Jemalloc 3.

Then, one day, hope appeared on the horizon. @wjordan offered a config for Jemalloc 5.

Ubuntu/Debian

FROM ruby:3.1.2-bullseye
RUN apt-get update ; \

DmitryTsepelev

ActiveRecord::Migration.remove_foreign_key(:current_table, :foreign_table) # no lock

ActiveRecord::Migration.add_column(:current_table, :column_bigint, :bigint) # no lock

copy_data = lambda do
  CurrentTable.where(column_bigint: nil).where.not(column: nil).in_batches do |batch|
    batch.update_all("column_bigint = column")
  end
end

zwolf

#!/usr/bin/env ruby

if `git diff HEAD spec` =~ /^\+.*,\s?(:focus|focus:\s?true|:focus\s?=>\s?true)/
  puts "\e[31mPlease focus and remove your :focus tags before committing :)"
  exit 1
end

parrish

SELECT bl.pid                 AS blocked_pid,
       a.usename              AS blocked_user,
       ka.query               AS current_statement_in_blocking_process,
       now() - ka.query_start AS blocking_duration,
       kl.pid                 AS blocking_pid,
       ka.usename             AS blocking_user,
       a.query                AS blocked_statement,
       now() - a.query_start  AS blocked_duration
FROM  pg_catalog.pg_locks         bl
 JOIN pg_catalog.pg_stat_activity a  ON a.pid = bl.pid

parrish

#!/bin/sh
# http://stackoverflow.com/a/6262715
# .git/hooks/pre-commit
# chmod +x .git/hooks/pre-commit

# A git hook script to find and fix trailing whitespace
# in your commits. Bypass it with the --no-verify option
# to git-commit
#