> ## Documentation Index
> Fetch the complete documentation index at: https://checkly-422f444a-immanuel-fix-api-spec.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Dev Image

> Use the dev agent for npm packages that require compilation.

If any of the checks you run on Private Locations rely on npm packages with native code, those packages need to be compiled during installation.

The standard agent is optimized for size and doesn’t ship with build tools. In those cases, you’ll need to use the **dev** image instead.

## When to Use the Dev Image

Use the **dev image** (`checkly/agent-dev:X.Y.Z`) when your checks require npm packages with **native dependencies** that need compilation. Common examples include:

* `sqlite3` - SQLite database
* `zookeeper` - Apache ZooKeeper client

If your checks only use pure JavaScript packages, the standard runtime image is recommended for its smaller size and faster startup.

## Available Tags

### Versioned Tags (Recommended)

```bash theme={null}
# Runtime (production)
docker pull checkly/agent:1.2.3

# Dev (with build tools)
docker pull checkly/agent-dev:1.2.3
```

### Floating Tags

```bash theme={null}
# Latest runtime release
docker pull checkly/agent:latest

# Latest dev release
docker pull checkly/agent-dev:latest
```

<Note>  Use versioned tags for reproducible deployments. Floating tags (like `:latest`) may change between pulls.</Note>

## What's Included in the Dev Image

The dev image adds the following to the standard image:

| Tool                 | Purpose                   |
| -------------------- | ------------------------- |
| `gcc`, `g++`, `make` | Compile native extensions |
| `python3`            | Required by node-gyp      |

These tools enable compilation of native Node.js modules during `npm install`.

## How to use it

The dev agent works exactly like the standard agent, but includes the build tools required to compile native modules.

To use the dev variant, simply change the image tag:

```bash Dev agent (with build tools) theme={null}
docker run \
  -e API_KEY="your_api_key_here" \
  --name checkly-agent-dev \
  -d checkly/agent-dev:latest
```

All other setup and configuration remains the same. For more information, see the [Private Locations documentation](/platform/private-locations/overview/).

## FAQ

### Can I use the dev image in production?

Yes, the dev image is production-ready. It contains the same runtime as the standard image, plus build tools. The only tradeoff is a larger image size.

### Do I need the dev image for Playwright checks?

No. Playwright and its dependencies are pre-installed in both variants. You only need the dev image if your check code imports npm packages with native dependencies.

### How do I know if a package needs the dev image?

If `npm install` fails with errors about `node-gyp`, `python`, `gcc`, or "compilation failed", you likely need the dev image.