Image Fetching

The [features.image_fetching] section controls how the gateway handles HTTP image URLs in chat requests. Non-OpenAI providers (Anthropic, Bedrock, Vertex) only accept base64 data URLs, so HTTP URLs must be fetched and converted.

Configuration Reference

[features.image_fetching]
enabled = true
max_size_mb = 20
timeout_secs = 30
allowed_content_types = ["image/png", "image/jpeg", "image/gif", "image/webp"]

Key	Type	Default	Description
`enabled`	boolean	`true`	Enable image URL fetching
`max_size_mb`	integer	`20`	Maximum image size in MB
`timeout_secs`	integer	`30`	Fetch timeout in seconds
`allowed_content_types`	array	common types	Allowed MIME types

Default Allowed Types

allowed_content_types = [
  "image/png",
  "image/jpeg",
  "image/gif",
  "image/webp"
]

Set to an empty array [] to allow all image/* types.

How It Works

Request contains image_url with HTTP URL
Gateway detects non-OpenAI provider (Anthropic, Bedrock, Vertex)
Gateway fetches image from URL
Image converted to base64 data URL
Modified request sent to provider

User Request                    Provider Request
┌─────────────────────┐        ┌─────────────────────┐
│ image_url:          │   →    │ image_url:          │
│   http://...        │        │   data:image/png;   │
│                     │        │   base64,...        │
└─────────────────────┘        └─────────────────────┘

Complete Examples

Standard Configuration

[features.image_fetching]
enabled = true
max_size_mb = 20
timeout_secs = 30
allowed_content_types = ["image/png", "image/jpeg", "image/gif", "image/webp"]

Permissive (All Image Types)

[features.image_fetching]
enabled = true
max_size_mb = 50
timeout_secs = 60
allowed_content_types = []  # Allow all image/* types

Restrictive

[features.image_fetching]
enabled = true
max_size_mb = 5
timeout_secs = 10
allowed_content_types = ["image/png", "image/jpeg"]

Disabled

[features.image_fetching]
enabled = false

When disabled, HTTP image URLs are passed through unchanged. Non-OpenAI providers will reject these requests.

Provider Behavior

Provider	HTTP URLs	Data URLs
OpenAI	Supported	Supported
Anthropic	Not supported	Supported
Bedrock	Not supported	Supported
Vertex	Not supported	Supported
Azure OpenAI	Supported	Supported

Error Handling

The gateway returns errors for:

Images exceeding max_size_mb
Fetch timeouts
Invalid or disallowed content types
Network errors fetching the image