Google Gemini Configuration

Overview

Google Gemini is a state-of-the-art Large Language Model (LLM) provided by Google. Fess can use the Google AI API (Generative Language API) to implement AI mode functionality with Gemini models.

Using Gemini enables high-quality response generation leveraging Google’s latest AI technology.

Key Features

  • Multimodal Support: Can process not only text but also images

  • Long Context: Long context window capable of processing large amounts of documents at once

  • Cost Efficiency: Flash models are fast and low-cost

  • Google Integration: Easy integration with Google Cloud services

Supported Models

Main models available with Gemini:

  • gemini-2.5-flash - Fast and efficient model (recommended)

  • gemini-2.5-pro - Model with higher reasoning capabilities

  • gemini-1.5-flash - Stable Flash model

  • gemini-1.5-pro - Stable Pro model

Note

For the latest information on available models, see Google AI for Developers.

Prerequisites

Before using Gemini, prepare the following.

  1. Google Account: A Google account is required

  2. Google AI Studio Access: Access https://aistudio.google.com/

  3. API Key: Generate an API key in Google AI Studio

Obtaining an API Key

  1. Access Google AI Studio

  2. Click “Get API key”

  3. Select “Create API key”

  4. Select an existing project or create a new one

  5. Securely save the generated API key

Warning

API keys are confidential information. Please note the following:

  • Do not commit to version control systems

  • Do not output to logs

  • Manage using environment variables or secure configuration files

Basic Configuration

Add the following settings to app/WEB-INF/conf/system.properties.

Minimal Configuration

# Enable AI mode functionality
rag.chat.enabled=true

# Set LLM provider to Gemini
rag.llm.type=gemini

# Gemini API key
rag.llm.gemini.api.key=AIzaSyxxxxxxxxxxxxxxxxxxxxxxxxx

# Model to use
rag.llm.gemini.model=gemini-2.5-flash

Configuration Options

All configuration options available for the Gemini client.

Property Description Default
rag.llm.gemini.api.key Google AI API key (Required)
rag.llm.gemini.model Model name to use gemini-2.5-flash
rag.llm.gemini.api.url API base URL https://generativelanguage.googleapis.com/v1beta
rag.llm.gemini.timeout Request timeout (in milliseconds) 60000

Environment Variable Configuration

For security reasons, it is recommended to configure API keys using environment variables.

Docker Environment

docker run -e RAG_LLM_GEMINI_API_KEY=AIzaSy... codelibs/fess:15.5.0

docker-compose.yml

services:
  fess:
    image: codelibs/fess:15.5.0
    environment:
      - RAG_CHAT_ENABLED=true
      - RAG_LLM_TYPE=gemini
      - RAG_LLM_GEMINI_API_KEY=${GEMINI_API_KEY}
      - RAG_LLM_GEMINI_MODEL=gemini-2.5-flash

systemd Environment

/etc/systemd/system/fess.service.d/override.conf:

[Service]
Environment="RAG_LLM_GEMINI_API_KEY=AIzaSy..."

Using via Vertex AI

If you are using Google Cloud Platform, you can also use Gemini via Vertex AI. When using Vertex AI, the API endpoint and authentication method differ.

Note

The current version of Fess uses the Google AI API (generativelanguage.googleapis.com). If you need to use Vertex AI, custom implementation may be required.

Model Selection Guide

Guidelines for selecting models based on intended use.

Model Speed Quality Use Case
gemini-2.5-flash Fast High General use, balanced approach (recommended)
gemini-2.5-pro Medium Highest Complex reasoning, when high quality is needed
gemini-1.5-flash Fast Good Cost-focused, stability-focused
gemini-1.5-pro Medium High When long context is needed

Context Window

Gemini models support very long context windows:

  • Gemini 1.5/2.5 Flash: Up to 1 million tokens

  • Gemini 1.5/2.5 Pro: Up to 2 million tokens

You can leverage this feature to include more search results in the context.

# Include more documents in context
rag.chat.context.max.documents=10
rag.chat.context.max.chars=20000

Cost Reference

Google AI API is billed based on usage (free tier available).

Model Input (per 1M characters) Output (per 1M characters)
Gemini 1.5 Flash $0.075 $0.30
Gemini 1.5 Pro $1.25 $5.00
Gemini 2.5 Flash Prices may vary Prices may vary

Note

For the latest pricing and free tier information, see Google AI Pricing.

Rate Limiting

Google AI API has rate limits. Configure appropriately in combination with Fess rate limiting functionality.

# Fess rate limit settings
rag.chat.rate.limit.enabled=true
rag.chat.rate.limit.requests.per.minute=10

Free Tier Limits

Google AI API has a free tier with the following limits:

  • Requests/minute: 15 RPM

  • Tokens/minute: 1 million TPM

  • Requests/day: 1,500 RPD

Troubleshooting

Authentication Errors

Symptom: API key-related errors occur

Check the following:

  1. Verify API key is correctly configured

  2. Verify API key is valid in Google AI Studio

  3. Verify API key has necessary permissions

  4. Verify the API is enabled for the project

Rate Limit Errors

Symptom: “429 Resource has been exhausted” error occurs

Solutions:

  1. Set stricter rate limits in Fess:

    rag.chat.rate.limit.requests.per.minute=5

  2. Wait a few minutes before retrying

  3. Request quota increase if necessary

Region Restrictions

Symptom: Service unavailable error

Check the following:

Google AI API is only available in certain regions. Please check Google’s documentation for supported regions.

Timeout

Symptom: Requests time out

Solutions:

  1. Extend timeout duration:

    rag.llm.gemini.timeout=120000

  2. Consider using Flash models (faster)

Debug Settings

When investigating issues, adjust Fess log levels to output detailed Gemini-related logs.

app/WEB-INF/classes/log4j2.xml:

<Logger name="org.codelibs.fess.llm.gemini" level="DEBUG"/>

Security Notes

When using Google AI API, please note the following security considerations.

  1. Data Privacy: Search result contents are sent to Google servers

  2. API Key Management: Key leakage can lead to unauthorized use

  3. Compliance: If handling confidential data, verify your organization’s policies

  4. Terms of Service: Comply with Google’s Terms of Service and Acceptable Use Policy

References