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Codex CLI is OpenAI’s open-source coding agent. This pack installs it on your EC2 instance and configures it as a builder agent: the sandbox is set to danger-full-access, the approval policy is set to never, and the model defaults to gpt-5.4. Authentication is deliberately deferred — the pack never embeds your OpenAI credentials in the instance, so you authenticate yourself after deploy by SSM-ing in and running codex login.
Experimental pack. Codex CLI uses OpenAI’s API — not Amazon Bedrock. Your prompts and code leave your AWS account and are processed under OpenAI’s terms of service. Expect rough edges as the upstream CLI evolves.
Codex CLI does not use Bedrock. It connects to OpenAI’s API directly. You need an OpenAI account and either a ChatGPT Plus subscription or an API key from platform.openai.com.

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What makes Codex CLI different

  • OpenAI provider. Uses OpenAI’s API instead of Bedrock. Auth is via ChatGPT browser login or an API key.
  • Builder-mode pre-configured. The pack writes ~/.codex/config.toml with sandbox_mode = "danger-full-access" and approval_policy = "never" — the agent runs commands without asking permission.
  • Post-install auth. The pack never stores your OpenAI key in deploy templates or shell history. You authenticate interactively after deploy by SSM-ing into the instance.

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Compatible profiles

All three profiles are supported, but builder is the recommended default for Codex CLI since the agent is configured with full filesystem and network access.

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Prerequisites

  • AWS CLI configured with admin access in a dedicated sandbox account
  • An OpenAI account with ChatGPT Plus or an API key from platform.openai.com
  • No Bedrock access, Docker, or interactive AWS login needed

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Install

After the stack finishes deploying, SSM into the instance and authenticate (see below). The agent will not work until you complete this step.

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Post-install: authenticate

Codex auth is intentionally deferred. SSM into the instance and choose one of these methods:
Verify authentication succeeded:

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Use the agent

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Configuration options

If you pass a Bedrock-style model ID (such as us.anthropic.claude-opus-4-6-v1) via --model, the pack detects it and falls back to gpt-5.4. OpenAI’s API returns HTTP 400 for Bedrock model IDs. This guard is intentional.
The managed block in ~/.codex/config.toml looks like this:

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Resource requirements

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Notes and limitations

  • Codex CLI is a pure CLI pack — no background service runs between sessions.
  • Authentication is not headless — you must SSM into the instance after deploy to complete the codex login step. Fully headless auth (e.g., via Secrets Manager) is not yet supported.
  • Your prompts and code leave your AWS account and go to OpenAI’s infrastructure. Review OpenAI’s data usage policy before use.
  • When you tear down the stack, Codex credentials on the instance vanish with the EBS volume. If the OpenAI key was shared with other systems, rotate it separately.