Ark Runtime Python SDK

The official Python library for the Volcengine Ark runtime API. It provides convenient access to the Ark REST API from any Python 3.8+ application, with both synchronous and asynchronous clients.

Installation

pip install arkruntime

Usage

Create a client by setting the ARK_API_KEY environment variable:

from arkruntime import Ark

client = Ark()
# or explicitly: Ark(api_key="your-api-key")

Responses API

import os
from arkruntime import Ark

client = Ark()

response = client.responses.create(
    model=os.environ.get("ARK_MODEL", "doubao-seed-2-1-pro-260628"),
    input="Explain how large language models work in three sentences.",
)
print(response.output_text)

Chat Completions

import os
from arkruntime import Ark

client = Ark()

completion = client.chat.completions.create(
    model=os.environ.get("ARK_MODEL", "doubao-seed-2-1-pro-260628"),
    messages=[
        {"role": "system", "content": "You are a helpful assistant."},
        {"role": "user", "content": "Write a haiku about programming."},
    ],
)
print(completion.choices[0].message.content)

Streaming

Both the Responses and Chat Completions APIs support streaming via stream=True.

Streaming responses

import os
from arkruntime import Ark

client = Ark()

stream = client.responses.create(
    model=os.environ.get("ARK_MODEL", "doubao-seed-2-1-pro-260628"),
    input="Count from 1 to 10 slowly.",
    stream=True,
)
for event in stream:
    print(event)

Streaming chat completions

import os
from arkruntime import Ark

client = Ark()

stream = client.chat.completions.create(
    model=os.environ.get("ARK_MODEL", "doubao-seed-2-1-pro-260628"),
    messages=[{"role": "user", "content": "Count from 1 to 10 slowly."}],
    stream=True,
)
for chunk in stream:
    if chunk.choices[0].delta.content:
        print(chunk.choices[0].delta.content, end="", flush=True)

Async usage

Every synchronous method has an async counterpart on AsyncArk.

import asyncio
import os
from arkruntime import AsyncArk

client = AsyncArk()

async def main():
    response = await client.responses.create(
        model=os.environ.get("ARK_MODEL", "doubao-seed-2-1-pro-260628"),
        input="Explain quantum computing briefly.",
    )
    print(response.output_text)

asyncio.run(main())

Vision

Pass images alongside text using multimodal content blocks.

import os
from arkruntime import Ark

client = Ark()

completion = client.chat.completions.create(
    model=os.environ.get("ARK_MODEL", "doubao-seed-2-1-pro-260628"),
    messages=[
        {
            "role": "user",
            "content": [
                {"type": "text", "text": "What is in this image?"},
                {"type": "image_url", "image_url": {"url": "https://example.com/photo.jpg"}},
            ],
        }
    ],
)
print(completion.choices[0].message.content)

Function calling

import json
import os
from arkruntime import Ark

client = Ark()

tools = [
    {
        "type": "function",
        "function": {
            "name": "get_weather",
            "description": "Get the current weather for a location.",
            "parameters": {
                "type": "object",
                "properties": {
                    "location": {"type": "string", "description": "City name"},
                },
                "required": ["location"],
            },
        },
    }
]

completion = client.chat.completions.create(
    model=os.environ.get("ARK_MODEL", "doubao-seed-2-1-pro-260628"),
    messages=[{"role": "user", "content": "What is the weather in Beijing?"}],
    tools=tools,
)

tool_call = completion.choices[0].message.tool_calls[0]
print(f"Function: {tool_call.function.name}")
print(f"Arguments: {tool_call.function.arguments}")

File uploads

from arkruntime import Ark

client = Ark()

# Upload a file
file = client.files.create(file=open("data.jsonl", "rb"), purpose="batch")
print(file.id)

# List files
for f in client.files.list():
    print(f.id, f.filename)

# Delete a file
client.files.delete(file.id)

Error handling

The SDK raises typed exceptions for API errors.

from arkruntime import Ark
from arkruntime._exceptions import ArkAPIError, ArkRateLimitError, ArkAuthenticationError

client = Ark()

try:
    client.chat.completions.create(
        model="doubao-seed-2-1-pro-260628",
        messages=[{"role": "user", "content": "Hello"}],
    )
except ArkRateLimitError:
    print("Rate limited — back off and retry.")
except ArkAuthenticationError:
    print("Invalid API key.")
except ArkAPIError as e:
    print(f"API error {e.status_code}: {e}")

The exception hierarchy:

ArkError
 +-- ArkAPIError
      +-- ArkAPIStatusError
      |    +-- ArkBadRequestError          (400)
      |    +-- ArkAuthenticationError       (401)
      |    +-- ArkPermissionDeniedError     (403)
      |    +-- ArkNotFoundError             (404)
      |    +-- ArkConflictError             (409)
      |    +-- ArkUnprocessableEntityError  (422)
      |    +-- ArkRateLimitError            (429)
      |    +-- ArkInternalServerError       (500)
      +-- ArkAPIConnectionError
      |    +-- ArkAPITimeoutError
      +-- ArkAPIResponseValidationError

Retries and timeouts

The client automatically retries failed requests (default: 2 retries) with backoff for transient errors.

from arkruntime import Ark

# Customize retries and timeout
client = Ark(
    max_retries=5,
    timeout=120.0,  # seconds
)

Per-request overrides are also supported:

client.chat.completions.create(
    model="doubao-seed-2-1-pro-260628",
    messages=[{"role": "user", "content": "Hello"}],
    timeout=30.0,
)

Batch inference

client.batch.* provides a synchronous high-throughput path with per-model concurrency control and automatic retry on 408/409/429/5xx. See the batch examples for thread-pool and async fan-out patterns.

from arkruntime import Ark

client = Ark(timeout=24 * 3600)

result = client.batch.chat.completions.create(
    model="doubao-seed-2-1-pro-260628",
    messages=[{"role": "user", "content": "Hello"}],
)
print(result)

API coverage

Examples

See the examples/ directory for runnable scripts:

• responses/ -- Responses API: multi-turn chat, function calling, structured output, video streaming
• chat/ -- Chat Completions: basic, function calling, reasoning, structured output, vision
• batch/ -- Batch inference: chat completions, embeddings, multimodal embeddings (sync + async)
• files/ -- Files API: upload, wait for processing, list, delete
• embeddings.py -- Text embeddings
• multimodal_embeddings.py -- Multimodal embeddings with image input
• content_generation_tasks.py -- Video generation task lifecycle
• image_generations.py -- Image generation
• tokenization.py -- Tokenization API

Development

This repo uses uv for dependency management.

uv sync                       # create venv + install runtime + dev deps
uv run pytest                 # run tests
uv run ruff check src/        # lint
uv run ruff format src/       # format

A pre-commit hook runs the same linting as CI:

uv run pre-commit install     # one-time setup

Requirements

• Python >= 3.8
• httpx >= 0.23.0
• pydantic >= 2.0
• typing-extensions >= 4.7