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Codex on Palmetto

Codex CLI is available on Palmetto for AI-assisted software development and HPC workflows. It can help with code understanding, log triage, Slurm script review, and small code changes.

warning

On Palmetto, start Codex only inside a Slurm allocation on a compute node. Do not run Codex on the login nodes.

info

If you want Codex to use Clemson's RCD LLM Service rather than OpenAI directly, see Using Codex with the RCD LLM Service.

Screenshot of the Codex CLI running in a terminal session

1. Start A Compute Session​

For interactive use, request a compute allocation first:

salloc --nodes 1 --ntasks 1 --cpus-per-task 4 --mem 8G --time 02:00:00
module load codex
codex

Open OnDemand terminal or shell sessions are also acceptable, since they run as interactive compute jobs.

2. Authenticate​

Codex supports ChatGPT sign-in and API-key sign-in.

  • For most cases, sign in with a Clemson-managed ChatGPT Edu account.
  • Clemson-managed OpenAI API keys are also supported and are a better fit for automation or scripted use.
  • If you want to use Clemson's RCD LLM Service instead of OpenAI directly, follow Using Codex with the RCD LLM Service.
  • Use device-code login:
codex login --device-auth

Keep ~/.codex/auth.json and API keys private. Do not put them in Git repositories, shared shell scripts, or support tickets.

See AI Tools at Clemson for Clemson-managed AI services.

3. Managed Defaults On Palmetto​

RCD applies managed defaults when Codex starts. Users can change these during a session, but the defaults are reapplied the next time Codex starts.

SettingDefaultWhy
approval_policyon-requestKeeps normal use low-friction while still surfacing risky actions
sandbox_modeworkspace-writeAllows normal editing inside the working directory
network access in workspace-writedisabledPrevents spawned commands from using network unless the user chooses to allow it

4. Enforced Restrictions​

RCD also applies admin-enforced requirements:

  • danger-full-access is not allowed.
  • approval never is not allowed.
  • Codex will prompt before sbatch, scancel, git push, and rm.
  • sudo and su are forbidden.

5. Typical Interactive Workflow​

A typical Codex session on Palmetto looks like this:

  1. Start in the project or working directory you actually want Codex to see.
  2. Ask Codex to explain the code, logs, or Slurm script before asking for changes.
  3. Make small changes, review the diff, and run small tests in the allocation.
  4. Review any job submission carefully before approving it.

Use Git checkpoints or commits before and after larger tasks.

6. Non-Interactive Use With codex exec​

codex exec is useful for bounded tasks such as log summarization, code review, or generating a short report from files in the current directory.

codex exec "Summarize the error in slurm-12345.out and suggest the next debugging step."

Because the Palmetto supported path does not allow approval never, batch or script use works best for read, analyze, and report tasks. If the task will need file edits, network access, or another prompted action, run it interactively instead.