GKE の GPU で vLLM を使用して Gemma オープンモデルを提供する

kubectl port-forward svc/llm-service 8080:8080 --namespace default &

Forwarding from 127.0.0.1:8080 -> 8080

curl http://127.0.0.1:8080/v1/chat/completions \
-X POST \
-H "Content-Type: application/json" \
-d '{
    "model": "google/gemma-4-26B-A4B-it",
    "messages": [
        {
          "role": "user",
          "content": "Why is the sky blue?"
        }
    ],
    "chat_template_kwargs": {
         "enable_thinking": true
    },
    "skip_special_tokens": false
}'

{
  "id": "chatcmpl-be75ccfcbdf753d1",
  "object": "chat.completion",
  "created": 1775006187,
  "model": "google/gemma-4-26B-A4B-it",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "The short answer is a phenomenon called **Rayleigh scattering**.\n\nTo understand how it works, you have to look at three things: sunlight, the Earth's atmosphere, and how light travels.\n\n### 1. Sunlight is a Rainbow\nAlthough sunlight looks white to us, it is actually made up of all the colors of the rainbow (red, orange, yellow, green, blue, indigo, and violet). Light travels as **waves**, and each color has a different wavelength:\n*   **Red light** travels in long, lazy, wide waves.\n*   **Blue and violet light** travel in short, choppy, tight waves.\n\n### 2. The Atmosphere is an Obstacle Course\nEarth's atmosphere is filled with gases (mostly nitrogen and oxygen). As sunlight travels through the atmosphere, it strikes the molecules of these gases. \n\nBecause the gas molecules are very small, they affect the colors differently based on their wavelength:\n*   The **long waves** (reds and yellows) pass through the atmosphere mostly straight, without hitting much. They are like large ocean waves that roll right over small pebbles.\n*   The **short waves** (blues and violets) strike the gas molecules and get scattered in every direction. They are like small ripples that hit a pebble and splash everywhere.\n\nBecause this blue light is being scattered in every direction by the air, when you look up, your eyes are catching that scattered blue light coming from every part of the sky.\n\n### 3. Why isn't the sky violet?\nIf violet light has an even shorter wavelength than blue light, you might wonder why the sky doesn't look purple. There are two main reasons:\n1.  **The Sun's output:** The Sun emits much more blue light than violet light.\n2.  **Human Biology:** Human eyes are much more sensitive to blue than to violet. Our eyes interpret the scatter of mixed blue and violet light simply as pale blue.\n\n---\n\n### Bonus: Why are sunsets red?\nWhen the sun is setting, it is much lower on the horizon. This means the sunlight has to travel through a much **thicker** layer of the atmosphere to reach your eyes. \n\nBy the time the light gets to you, the blue light has been scattered away completely로. Only the long-wavelength colors—the reds, oranges, and pinks—are able to make it through that thick layer of air without being scattered away, creating the beautiful colors of a sunset.",
        "refusal": null,
        "annotations": null,
        "audio": null,
        "function_call": null,
        "tool_calls": [],
        "reasoning": "\"Why is the sky blue?\"\nScience/Physics (Atmospheric scattering).\nExplain the phenomenon clearly, accurately, and engagingly.\n\n    *   Sunlight (white light) is made of a spectrum of colors (ROYGBIV).\n    *   Earth's atmosphere is filled with gases (nitrogen, oxygen) and particles.\n    *   Rayleigh Scattering: Shorter wavelengths (blue/violet) scatter more easily than longer wavelengths (red/yellow) when hitting small gas molecules.\n    *   The human eye's sensitivity: Why isn't it violet?\n\n    A good scientific explanation should follow a logical flow:\n    *   *Direct Answer:* The core mechanism (Rayleigh Scattering).\n    *   *The Components:* Sunlight and the Atmosphere.\n    *   *The Mechanism:* How light interacts with gas molecules.\n    *   *The Wavelength Factor:* Comparing colors.\n    *   *The \"Wait, why not violet?\" question:* Addressing human perception.\n    *   *Bonus/Related concept:* Why sunsets are red.\n\n        *   Use the term **Rayleigh Scattering**.\n        *   Summarize: Its how sunlight interacts with the Earth's atmosphere.\n\n        *   Sunlight looks white, but it's actually a mix of all colors (the rainbow).\n        *   Each color travels as a different wavelength. Red = long/lazy waves; Blue/Violet = short/choppy waves.\n\n        *   The atmosphere is mostly Nitrogen and Oxygen.\n        *   When sunlight hits these tiny gas molecules, the light gets scattered in all directions.\n\n        *   Blue light travels in shorter, smaller waves.\n        *   Because these waves are small, they strike the gas molecules more frequently and get scattered more easily than the longer red/yellow waves.\n        *   Result: When you look up, your eyes are catching this \"scattered\" blue light coming from every direction.\n\n        *   *Technically*, violet light has an even shorter wavelength than blue, so it scatters *even more*. Why isn't the sky violet?\n        *   Two reasons: 1. The Sun emits more blue light than violet light. 2. Human eyes are much more sensitive to blue than violet.\n\n        *   Briefly mention sunsets to provide a complete picture.\n        *   At sunset, light travels through *more* atmosphere. The blue is scattered away completely, leaving only the long red/orange waves to reach your eyes.\n\n    *   *Tone Check:* Is it too academic? Use analogies (like waves in water or skipping stones) if needed, but keep it concise.\n    *   *Clarity:* Ensure the distinction between wavelength and scattering is clear."
      },
      "logprobs": null,
      "finish_reason": "stop",
      "stop_reason": 106,
      "token_ids": null
    }
  ],
  "service_tier": null,
  "system_fingerprint": null,
  "usage": {
    "prompt_tokens": 21,
    "total_tokens": 1122,
    "completion_tokens": 1101,
    "prompt_tokens_details": null
  },
  "prompt_logprobs": null,
  "prompt_token_ids": null,
  "kv_transfer_params": null
}