Passthrough

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Overview

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Endpoints

• /openai_passthrough
  Default provider: openai
• /genai_passthrough
  Default provider: gemini (with automatic Vertex detection for clients configured to use Vertex)

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How It Works

1. Send your request to a passthrough endpoint (OpenAI or GenAI passthrough).
2. The integration strips the passthrough prefix and forwards the remaining provider-native path/body.
3. Bifrost handles provider execution through core inference and plugin pipelines.
4. Response status, headers, and body are returned as passthrough output (for both stream and non-stream requests).

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Provider Selection Rules

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OpenAI Passthrough

• Uses openai as the default provider.

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GenAI Passthrough

• Uses gemini by default.
• Automatically switches to vertex when Vertex patterns are detected, such as:
  • URL path containing /projects/{PROJECT_ID}/locations/{LOCATION}/
  • Request body model containing a Vertex resource path
  • OAuth token pattern typically used for Vertex (Bearer ya29...)

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Usage Examples

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OpenAI Passthrough

import openai

client = openai.OpenAI(
    base_url="http://localhost:8080/openai_passthrough/v1",
    api_key="dummy-key"
)

response = client.chat.completions.create(
    model="gpt-4o-mini",
    messages=[{"role": "user", "content": "hello from passthrough"}]
)

print(response.choices[0].message.content)

curl -X POST "http://localhost:8080/openai_passthrough/v1/chat/completions" \
  -H "content-type: application/json" \
  -H "authorization: Bearer sk-your-openai-key" \
  -d '{
    "model": "gpt-4o-mini",
    "messages": [{"role":"user","content":"hello from passthrough"}]
  }'

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GenAI Passthrough (Gemini)

from google import genai
from google.genai.types import HttpOptions

client = genai.Client(
    api_key="dummy-key",
    http_options=HttpOptions(base_url="http://localhost:8080/genai_passthrough")
)

response = client.models.generate_content(
    model="gemini-2.5-flash",
    contents="hello from passthrough"
)

print(response.text)

curl -X POST "http://localhost:8080/genai_passthrough/v1beta/models/gemini-2.5-flash:generateContent" \
  -H "content-type: application/json" \
  -H "x-goog-api-key: your-gemini-key" \
  -d '{
    "contents":[{"parts":[{"text":"hello from passthrough"}]}]
  }'

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GenAI Passthrough (Vertex-style request)

from google import genai
from google.genai.types import HttpOptions

client = genai.Client(
    vertexai=True,
    api_key="dummy-key",
    http_options=HttpOptions(base_url="http://localhost:8080/genai_passthrough")
)

response = client.models.generate_content(
    model="gemini-2.5-flash",
    contents="hello from vertex passthrough"
)

print(response.text)

curl -X POST "http://localhost:8080/genai_passthrough/v1/projects/my-project/locations/us-central1/publishers/google/models/gemini-2.5-flash:generateContent" \
  -H "content-type: application/json" \
  -H "authorization: Bearer ya29.your-vertex-token" \
  -d '{
    "contents":[{"parts":[{"text":"hello from vertex passthrough"}]}]
  }'

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Notes

• Use passthrough when you need a provider endpoint that is not directly supported by Bifrost integration routes yet.