Codex CIモードをGithub Actionsで試してみた！

はじめに

CodexのCIモードをGithub Actions試してみました。

公式サンプル

- name: Update changelog via Codex
  run: |
    npm install -g @openai/codex
    codex login --api-key "${{ secrets.OPENAI_KEY }}"
    codex exec --full-auto "update CHANGELOG for next release"

実装してみた

.github/workflows/codex.yml

name: Hello Codex
on:
  workflow_dispatch:

jobs:
  codex:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v5

      - name: Setup Node.js
        uses: actions/setup-node@v5
        with:
          node-version: 24

      - name: Hello Codex
        run: |
          npm install -g @openai/codex
          mkdir ~/.codex
          codex login --api-key "${{ secrets.OPENAI_KEY }}"
          codex exec --full-auto "こんにちは！"

codexコマンドの実行前に.codexディレクトリが存在しないと以下のエラーが出ます。

Error logging in: No such file or directory (os error 2)
Error: Process completed with exit code 1.

ワークフロー実行

コマンドまたは画面から手動で実行します。

gh workflow run codex.yml

出力結果

Successfully logged in
[2025-09-19T06:43:04] OpenAI Codex v0.39.0 (research preview)
--------
workdir: /home/runner/work/codex-cli-actions/codex-cli-actions
model: gpt-5
provider: openai
approval: never
sandbox: workspace-write [workdir, /tmp, $TMPDIR]
reasoning effort: none
reasoning summaries: auto
--------
[2025-09-19T06:43:04] User instructions:
こんにちは！

[2025-09-19T06:43:08] thinking

こんにちは！今日は何をお手伝いできますか？ I think it's best to keep things simple and friendly. There's no need for tools or extra explanations. Just providing that greeting should be enough! I want to ensure my response aligns with the tone guidelines and feels welcoming. Let’s keep it straightforward, focusing on how I can assist without getting too complicated.

参考