hermes-agent/website/docs/user-guide/messaging/open-webui.md

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8	Open WebUI	Connect Open WebUI to Hermes Agent via the OpenAI-compatible API server

Open WebUI Integration

Open WebUI (126k★) is the most popular self-hosted chat interface for AI. With Hermes Agent's built-in API server, you can use Open WebUI as a polished web frontend for your agent — complete with conversation management, user accounts, and a modern chat interface.

Architecture

flowchart LR
    A["Open WebUI<br/>browser UI<br/>port 3000"]
    B["hermes-agent<br/>gateway API server<br/>port 8642"]
    A -->|POST /v1/chat/completions| B
    B -->|SSE streaming response| A

Open WebUI connects to Hermes Agent's API server just like it would connect to OpenAI. Your agent handles the requests with its full toolset — terminal, file operations, web search, memory, skills — and returns the final response.

Open WebUI talks to Hermes server-to-server, so you do not need API_SERVER_CORS_ORIGINS for this integration.

Quick Setup

1. Enable the API server

Add to ~/.hermes/.env:

API_SERVER_ENABLED=true
API_SERVER_KEY=your-secret-key

2. Start Hermes Agent gateway

hermes gateway

You should see:

[API Server] API server listening on http://127.0.0.1:8642

3. Start Open WebUI

docker run -d -p 3000:8080 \
  -e OPENAI_API_BASE_URL=http://host.docker.internal:8642/v1 \
  -e OPENAI_API_KEY=your-secret-key \
  --add-host=host.docker.internal:host-gateway \
  -v open-webui:/app/backend/data \
  --name open-webui \
  --restart always \
  ghcr.io/open-webui/open-webui:main

4. Open the UI

Go to http://localhost:3000. Create your admin account (the first user becomes admin). You should see hermes-agent in the model dropdown. Start chatting!

Docker Compose Setup

For a more permanent setup, create a docker-compose.yml:

services:
  open-webui:
    image: ghcr.io/open-webui/open-webui:main
    ports:
      - "3000:8080"
    volumes:
      - open-webui:/app/backend/data
    environment:
      - OPENAI_API_BASE_URL=http://host.docker.internal:8642/v1
      - OPENAI_API_KEY=your-secret-key
    extra_hosts:
      - "host.docker.internal:host-gateway"
    restart: always

volumes:
  open-webui:

Then:

docker compose up -d

Configuring via the Admin UI

If you prefer to configure the connection through the UI instead of environment variables:

1. Log in to Open WebUI at http://localhost:3000
2. Click your profile avatar → Admin Settings
3. Go to Connections
4. Under OpenAI API, click the wrench icon (Manage)
5. Click + Add New Connection
6. Enter:
   • URL: http://host.docker.internal:8642/v1
   • API Key: your key or any non-empty value (e.g., not-needed)
7. Click the checkmark to verify the connection
8. Save

The hermes-agent model should now appear in the model dropdown.

:::warning Environment variables only take effect on Open WebUI's first launch. After that, connection settings are stored in its internal database. To change them later, use the Admin UI or delete the Docker volume and start fresh. :::

API Type: Chat Completions vs Responses

Open WebUI supports two API modes when connecting to a backend:

Mode	Format	When to use
Chat Completions (default)	/v1/chat/completions	Recommended. Works out of the box.
Responses (experimental)	/v1/responses	For server-side conversation state via previous_response_id.

Using Chat Completions (recommended)

This is the default and requires no extra configuration. Open WebUI sends standard OpenAI-format requests and Hermes Agent responds accordingly. Each request includes the full conversation history.

Using Responses API

To use the Responses API mode:

1. Go to Admin Settings → Connections → OpenAI → Manage
2. Edit your hermes-agent connection
3. Change API Type from "Chat Completions" to "Responses (Experimental)"
4. Save

With the Responses API, Open WebUI sends requests in the Responses format (input array + instructions), and Hermes Agent can preserve full tool call history across turns via previous_response_id.

:::note Open WebUI currently manages conversation history client-side even in Responses mode — it sends the full message history in each request rather than using previous_response_id. The Responses API mode is mainly useful for future compatibility as frontends evolve. :::

How It Works

When you send a message in Open WebUI:

1. Open WebUI sends a POST /v1/chat/completions request with your message and conversation history
2. Hermes Agent creates an AIAgent instance with its full toolset
3. The agent processes your request — it may call tools (terminal, file operations, web search, etc.)
4. As tools execute, inline progress messages stream to the UI so you can see what the agent is doing (e.g. `💻 ls -la`, `🔍 Python 3.12 release`)
5. The agent's final text response streams back to Open WebUI
6. Open WebUI displays the response in its chat interface

Your agent has access to all the same tools and capabilities as when using the CLI or Telegram — the only difference is the frontend.

:::tip Tool Progress With streaming enabled (the default), you'll see brief inline indicators as tools run — the tool emoji and its key argument. These appear in the response stream before the agent's final answer, giving you visibility into what's happening behind the scenes. :::

Configuration Reference

Hermes Agent (API server)

Variable	Default	Description
API_SERVER_ENABLED	false	Enable the API server
API_SERVER_PORT	8642	HTTP server port
API_SERVER_HOST	127.0.0.1	Bind address
API_SERVER_KEY	(required)	Bearer token for auth. Match OPENAI_API_KEY.

Open WebUI

Variable	Description
OPENAI_API_BASE_URL	Hermes Agent's API URL (include /v1)
OPENAI_API_KEY	Must be non-empty. Match your API_SERVER_KEY.

Troubleshooting

No models appear in the dropdown

• Check the URL has /v1 suffix: http://host.docker.internal:8642/v1 (not just :8642)
• Verify the gateway is running: curl http://localhost:8642/health should return {"status": "ok"}
• Check model listing: curl http://localhost:8642/v1/models should return a list with hermes-agent
• Docker networking: From inside Docker, localhost means the container, not your host. Use host.docker.internal or --network=host.

Connection test passes but no models load

This is almost always the missing /v1 suffix. Open WebUI's connection test is a basic connectivity check — it doesn't verify model listing works.

Response takes a long time

Hermes Agent may be executing multiple tool calls (reading files, running commands, searching the web) before producing its final response. This is normal for complex queries. The response appears all at once when the agent finishes.

"Invalid API key" errors

Make sure your OPENAI_API_KEY in Open WebUI matches the API_SERVER_KEY in Hermes Agent.

Linux Docker (no Docker Desktop)

On Linux without Docker Desktop, host.docker.internal doesn't resolve by default. Options:

# Option 1: Add host mapping
docker run --add-host=host.docker.internal:host-gateway ...

# Option 2: Use host networking
docker run --network=host -e OPENAI_API_BASE_URL=http://localhost:8642/v1 ...

# Option 3: Use Docker bridge IP
docker run -e OPENAI_API_BASE_URL=http://172.17.0.1:8642/v1 ...