> ## Documentation Index
> Fetch the complete documentation index at: https://docs.appsignal.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Celery Instrumentation

export const VersionRequirements = ({versions = []}) => {
  if (!Array.isArray(versions) || versions.length === 0) {
    return null;
  }
  const boundaries = {
    upper: " or lower",
    exact: "",
    lower: " or higher"
  };
  const containerStyle = {
    marginTop: "0.5rem",
    marginBottom: "1.5rem"
  };
  const lineStyle = {
    display: "block",
    margin: "0 0 0.35rem 0",
    fontSize: "0.875rem",
    lineHeight: "1.4"
  };
  const pillBaseStyle = {
    display: "inline-block",
    padding: "0.1em 0.4em",
    borderRadius: "0.25rem",
    border: "1px solid",
    fontFamily: "ui-monospace, SFMono-Regular, Menlo, monospace",
    fontSize: "0.85em",
    fontWeight: 500
  };
  const pillColors = {
    "AppSignal for Elixir": {
      background: "#f3e8ff",
      borderColor: "#e9d5ff",
      color: "#9333ea"
    },
    "AppSignal for Front-end": {
      background: "#fef9c3",
      borderColor: "#fde68a",
      color: "#ca8a04"
    },
    "AppSignal for Go": {
      background: "#ccfbf1",
      borderColor: "#99f6e4",
      color: "#0d9488"
    },
    "AppSignal for JavaScript": {
      background: "#fef9c3",
      borderColor: "#fde68a",
      color: "#ca8a04"
    },
    "AppSignal for Node.js": {
      background: "#dcfce7",
      borderColor: "#bbf7d0",
      color: "#16a34a"
    },
    "AppSignal for Python": {
      background: "#dbeafe",
      borderColor: "#bfdbfe",
      color: "#2563eb"
    },
    "AppSignal for Ruby": {
      background: "#fee2e2",
      borderColor: "#fecaca",
      color: "#dc2626"
    },
    "AppSignal for Rust": {
      background: "#ffedd5",
      borderColor: "#fed7aa",
      color: "#ea580c"
    }
  };
  const defaultPillColor = {
    background: "#f4f4f5",
    borderColor: "#e4e4e7",
    color: "#52525b"
  };
  const getPillStyle = name => ({
    ...pillBaseStyle,
    ...pillColors[name] || defaultPillColor
  });
  const getBoundText = bound => {
    return boundaries[bound] || boundaries.lower;
  };
  return <div style={containerStyle}>
      {versions.map((v, i) => <p key={`${v.name}-${v.version}-${v.bound || "lower"}-${i}`} style={lineStyle}>
          This feature requires{" "}
          <code style={getPillStyle(v.name)}>{v.name}</code> version {v.version}
          {getBoundText(v.bound)}.
        </p>)}
    </div>;
};

<VersionRequirements
  versions={[
{ name: "AppSignal for Python", version: "0.1.0" },
{ name: "Celery", version: "4.0" }
]}
/>

[Celery](https://github.com/celery/celery) is a simple, flexible, and reliable distributed system to process vast amounts of messages, while providing operations with the tools required to maintain such a system.

## Installation

<Note>
  🐍 Don't forget to [install the AppSignal for Python package](/python/installation) in your application first.
</Note>

First, install the `opentelemetry-instrumentation-celery` package. We also recommend installing the [Redis](/python/instrumentations/redis) instrumentation package. To add both instrumentation packages to your project, add the following lines to your `requirements.txt` file:

<CodeGroup>
  ```python Python theme={null}

  <PythonDisableInstrumentations />
  # requirements.txt
  opentelemetry-instrumentation-celery
  opentelemetry-instrumentation-redis
  ```
</CodeGroup>

## Setup

Celery requires some extra setup, as it's an application component that's started separately.

As shown in the example below, the `appsignal` module needs to be imported in the main file used to start Celery, and the `appsignal.start()` method needs to be called from a method with the `@worker_process_init.connect` decorator.

In the example below, this initialization takes place in the `tasks.py` file. This file may be named differently in your application.

<CodeGroup>
  ```python Python theme={null}
  # tasks.py

  # Import this file
  import appsignal

  from celery import Celery

  # Import this file
  from celery.signals import worker_process_init

  # Add the init_celery_tracing method with its annotation
  @worker_process_init.connect(weak=False)
  def init_celery_tracing(*args, **kwargs):
      appsignal.start()

  app = Celery('tasks', broker='redis://localhost')

  @app.task
  def slow_task():
      # Do things
  ```
</CodeGroup>