api-emulator

Simple API emulator for OpenAI API and Ollama API, built with FastAPI and deployable on Google App Engine.

Endpoints

OpenAI-style:

• GET /v1/models
• POST /v1/chat/completions
• POST /v1/completions
• POST /v1/embeddings

Ollama-style:

• GET /api/tags
• POST /api/generate
• POST /api/chat

Health:

• GET /healthz

Image emulation:

• POST /image (returns dummy image/png)

Run locally

python -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt
uvicorn main:app --reload

Quick test

OpenAI chat completion:

curl -s http://127.0.0.1:8000/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-4o-mini",
    "messages": [{"role": "user", "content": "Hello"}]
  }'

Ollama generate:

curl -s http://127.0.0.1:8000/api/generate \
  -H "Content-Type: application/json" \
  -d '{"model": "llama3", "prompt": "Say hi"}'

Deploy to Google App Engine

gcloud app deploy

After deployment, replace your client base URL with your App Engine URL.

GitHub Actions (PR test + deploy on merge)

Workflow file: .github/workflows/ci-cd.yml

• On pull_request to main: installs dependencies and runs pytest.
• On push to main (including merged PRs): runs tests, then deploys to App Engine.

Required GitHub repository secrets:

• GCP_SA_KEY: Google Cloud service account key JSON (as secret value).
• GCP_PROJECT_ID: Google Cloud project ID.