docs: add Gemini/Vertex AI to prompt caching docs

Add Google AI Studio (gemini/) and Vertex AI (vertex_ai/) as
supported providers for prompt caching. Same cache_control format
as Anthropic works - LiteLLM translates it to Google's context
caching API under the hood.

Includes SDK + proxy examples for both providers.
This commit is contained in:
Klaus
2026-03-20 09:48:31 -07:00
parent d7c419bfee
commit 330ef5e579
@@ -6,6 +6,8 @@ import TabItem from '@theme/TabItem';
Supported Providers:
- OpenAI (`openai/`)
- Anthropic API (`anthropic/`)
- Google AI Studio (`gemini/`)
- Vertex AI (`vertex_ai/`, `vertex_ai_beta/`)
- Bedrock (`bedrock/`, `bedrock/invoke/`, `bedrock/converse`) ([All models bedrock supports prompt caching on](https://docs.aws.amazon.com/bedrock/latest/userguide/prompt-caching.html))
- Deepseek API (`deepseek/`)
@@ -257,7 +259,7 @@ Anthropic charges for cache writes.
Specify the content to cache with `"cache_control": {"type": "ephemeral"}`.
If you pass that in for any other llm provider, it will be ignored.
This same format also works for [Gemini / Vertex AI](#google-ai-studio--vertex-ai-gemini-example). For other providers, it will be ignored.
<Tabs>
<TabItem value="sdk" label="SDK">
@@ -356,6 +358,208 @@ print(response.usage)
</TabItem>
</Tabs>
### Google AI Studio / Vertex AI (Gemini) Example
Use the same Anthropic-style `cache_control` format — LiteLLM automatically translates it to Google's [context caching API](https://ai.google.dev/api/caching).
**How it works under the hood:**
1. Messages with `cache_control` are separated and sent to Google's `cachedContents` API
2. The cached content ID is then passed as `cachedContent` in the Gemini request body
3. Works across all three providers: `gemini/` (Google AI Studio), `vertex_ai/`, and `vertex_ai_beta/`
4. Requires a minimum of **1024 tokens** in the cached content — below that, caching is silently skipped
<Tabs>
<TabItem value="sdk" label="SDK">
```python
from litellm import completion
import os
os.environ["GEMINI_API_KEY"] = ""
response = completion(
model="gemini/gemini-2.5-flash",
messages=[
{
"role": "system",
"content": [
{
"type": "text",
"text": "You are an AI assistant tasked with analyzing legal documents.",
},
{
"type": "text",
"text": "Here is the full text of a complex legal agreement" * 400,
"cache_control": {"type": "ephemeral"},
},
],
},
{
"role": "user",
"content": "what are the key terms and conditions in this agreement?",
},
],
)
print(response.usage)
```
</TabItem>
<TabItem value="proxy" label="PROXY">
1. Setup config.yaml
```yaml
model_list:
- model_name: gemini-2.5-flash
litellm_params:
model: gemini/gemini-2.5-flash
api_key: os.environ/GEMINI_API_KEY
```
2. Start proxy
```bash
litellm --config /path/to/config.yaml
```
3. Test it!
```python
from openai import OpenAI
client = OpenAI(
api_key="LITELLM_PROXY_KEY", # sk-1234
base_url="LITELLM_PROXY_BASE", # http://0.0.0.0:4000
)
response = client.chat.completions.create(
model="gemini-2.5-flash",
messages=[
{
"role": "system",
"content": [
{
"type": "text",
"text": "You are an AI assistant tasked with analyzing legal documents.",
},
{
"type": "text",
"text": "Here is the full text of a complex legal agreement" * 400,
"cache_control": {"type": "ephemeral"},
},
],
},
{
"role": "user",
"content": "what are the key terms and conditions in this agreement?",
},
],
)
print(response.usage)
```
</TabItem>
</Tabs>
#### Vertex AI
For Vertex AI, use `vertex_ai/` prefix:
<Tabs>
<TabItem value="sdk" label="SDK">
```python
from litellm import completion
response = completion(
model="vertex_ai/gemini-2.5-flash",
vertex_project="my-gcp-project",
vertex_location="us-central1",
messages=[
{
"role": "system",
"content": [
{
"type": "text",
"text": "You are an AI assistant tasked with analyzing legal documents.",
},
{
"type": "text",
"text": "Here is the full text of a complex legal agreement" * 400,
"cache_control": {"type": "ephemeral"},
},
],
},
{
"role": "user",
"content": "what are the key terms and conditions in this agreement?",
},
],
)
print(response.usage)
```
</TabItem>
<TabItem value="proxy" label="PROXY">
1. Setup config.yaml
```yaml
model_list:
- model_name: gemini-2.5-flash
litellm_params:
model: vertex_ai/gemini-2.5-flash
vertex_project: my-gcp-project
vertex_location: us-central1
```
2. Start proxy
```bash
litellm --config /path/to/config.yaml
```
3. Test it!
```python
from openai import OpenAI
client = OpenAI(
api_key="LITELLM_PROXY_KEY", # sk-1234
base_url="LITELLM_PROXY_BASE", # http://0.0.0.0:4000
)
response = client.chat.completions.create(
model="gemini-2.5-flash",
messages=[
{
"role": "system",
"content": [
{
"type": "text",
"text": "You are an AI assistant tasked with analyzing legal documents.",
},
{
"type": "text",
"text": "Here is the full text of a complex legal agreement" * 400,
"cache_control": {"type": "ephemeral"},
},
],
},
{
"role": "user",
"content": "what are the key terms and conditions in this agreement?",
},
],
)
print(response.usage)
```
</TabItem>
</Tabs>
### Deepeek Example
Works the same as OpenAI.