# Monitoring Celery with Flower

**Flower** is a web-based tool for monitoring and administrating Celery clusters. It provides real-time information about the state of your workers and tasks.

## Installation

Flower is a Python package that can be installed via pip.

```bash
pip install flower
```

## Running Flower

To start Flower, you use the `celery` command line interface. You need to point it to your Celery application instance (just like you do for the worker).

Assuming your project structure has a `tasks.py` or `main.py` where the Celery app is defined:

```bash
celery -A tasks flower
```

*   `-A tasks`: Specifies the application module.
*   `flower`: The command to start the web server.

By default, Flower starts a web server on port **5555**.

## Accessing the Dashboard

Open your web browser and navigate to:

`http://localhost:5555`

## Key Features

### 1. Real-time Monitoring
View task progress and history. You can see which tasks are currently executing, which have succeeded, and which have failed.

### 2. Worker Status
See the status of all workers in your cluster.
*   **Online/Offline status**
*   **Load average**
*   **Memory usage**

### 3. Remote Control
Flower allows you to control your workers remotely:
*   **Restart** worker pools.
*   **Grow/Shrink** the worker pool (add or remove concurrent processes).
*   **Rate Limit**: Change the rate limit of a task type on the fly.
*   **Revoke**: Cancel executing tasks.

## Production Configuration

### Basic Authentication
To protect the dashboard in a production environment, you can enable Basic Auth.

```bash
celery -A tasks flower --basic_auth=username:password
```

See also: [[programming/python/celery|Celery Basics]]

[[programming/python/python]]