Mitchell Hashimoto’s new way of writing code

The Pragmatic Engineer 1h58 3 min #68
Mitchell Hashimoto’s new way of writing code
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Summary

  • Mitchell Hashimoto, co-founder of HashiCorp and creator of Ghostty, reflects on building foundational cloud infrastructure tools, the near-sale of HashiCorp to VMware, his candid views on AWS/Azure/GCP, and how AI is reshaping open source, software engineering, and his own daily workflow.
    • He grew up self-teaching programming via open source, studied at University of Washington, and got his first job through a cold email as a Ruby on Rails consultant.
    • A failed university research project on distributed computing led him to list unsolved infrastructure problems in a notebook—those ideas became the blueprint for HashiCorp’s product stack.
    • He co-founded HashiCorp with Arman Dadger after a two-minute email exchange, initially self-funding with $20k and paying himself nothing for six months.
    • The company’s early products—Packer, Consul, Terraform, Vault, and Nomad—solved core cloud infrastructure challenges: image building, service discovery, declarative provisioning, secrets management, and workload scheduling.
    • Their first commercial product (Atlas) failed because it required adopting all tools and created internal budget conflicts; they pivoted over a single weekend to an open-core, per-product enterprise model starting with Vault.
    • Terraform became dominant despite being seventh to market, largely due to relentless community engagement and Mitchell’s constant travel and advocacy.
    • HashiCorp went public in 2021; Mitchell stepped down from the executive team six months prior.
    • VMware nearly acquired HashiCorp two years in for $100M using a regret-minimization framework, but the deal failed by one board vote—likely preventing Terraform from ever being built.

Mitchell’s honest take on cloud providers

  • AWS: Felt arrogant and unhelpful; acted like partners were lucky to engage, and subtly threatened to build competing services. Only began supporting Terraform after HashiCorp threatened to deprecate the AWS provider.
  • Microsoft Azure: Technically complex and hard to navigate, but business teams were professional, collaborative, and consistently supportive—first to back Terraform.
  • Google Cloud: Built the best technology (e.g., automated provider generation), but ignored business alignment—no interest in co-selling or quota attribution.

AI’s impact on open source and Ghostty

  • After leaving HashiCorp, Mitchell built Ghostty—a modern, opinionated terminal emulator using Zig and GPU rendering—to relearn systems programming and explore new tech like GPUs.
    • Ghostty is architecturally split into UI, IO, and renderer threads; its performance focus reduced frame processing to ~9 microseconds.
    • He extracted libghosty, a minimal, embeddable terminal library, to fix widespread broken terminal implementations in tools like Docker and Heroku.
  • AI has flooded open source with low-effort, plausible-looking but incorrect contributions.
    • Ghostty initially required AI disclosure, then banned AI PRs without accepted feature requests, and is now moving to a vouching system inspired by Lobsters and the PI project.
      • New contributors must be vouched for by trusted community members; bad actors can be denounced, blocking them and their inviter’s tree.
    • He believes open source must shift from “default trust” to “default deny,” emphasizing reputation and human accountability.

How Mitchell uses AI daily

  • He always has at least one agent running—coding, researching, or analyzing—while he focuses on higher-level thinking.
    • Agents run in separate tabs; he disables all notifications and controls when to check in.
    • Example: While driving to this podcast, he had an agent map out libraries with specific licenses and properties.
  • He delegates non-thinking tasks (boilerplate, research, edge-case analysis) to agents but reviews all code going into Ghostty.
  • His advice for engineers new to AI: reproduce your existing work with an agent—either coding or research—to learn its strengths and limits through deliberate practice.

Broader shifts in software engineering

  • Git and monorepos are under strain from AI-generated code volume: merge queues grow unmanageable, context becomes harder to find, and branching workflows don’t preserve failed experiments.
  • CI/CD and testing must evolve: agents need expansive test harnesses to validate behavior and avoid breaking unrelated features.
  • Observability and sandboxing face new scale pressures from ephemeral agent environments.
  • Hiring: The best engineers often have quiet, private backgrounds—no social media, no side projects—but are deeply focused during work hours.
    • He values candidates who use AI tools strategically, especially for rapid prototyping and research.

Advice for aspiring founders

  • Startups take longer than you think—plan for 10 years, not 5.
  • You need enough hubris to believe you’ll do it better than anyone, but not so much that you ignore market signals.
  • Most common questions: whether to open source, go remote, or target enterprise—all depend on context.
  • AI startups face extreme pressure to move fast, but productionizing still requires rigor.

Personal insights

  • He recharges through quiet solo time—walking near the beach, thinking through problems in the dark before sleep.
  • Reads mostly fiction; recommends The Invisible Life of Addie LaRue for its exploration of immortality and human connection.
  • Believes the key to staying competitive is thinking more about the problem than others—not working longer hours, but never fully switching off.
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