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

# nsc github base-image describe

Show details for a specific GitHub runner base image.

`nsc github base-image describe` prints the full details of a single base image, identified by its label (for example `ubuntu-26.04`). The output includes the image reference, the operating system, the enabled features, and the complete list of installed packages with their versions.

Pass `-o json` to get a machine-readable representation that is easy to diff between two images, for example to compare `ubuntu-26.04` against `ubuntu-24.04`. You can also browse the same information in the dashboard, for example [ubuntu-26.04](https://cloud.namespace.so/workspace/actions/image/ubuntu-26.04).

## Usage

```bash theme={null}
nsc github base-image describe <label> [flags]
```

### Examples

**Describe a base image:**

```bash theme={null}
nsc github base-image describe ubuntu-26.04
```

**Describe a base image as JSON:**

```bash theme={null}
nsc github base-image describe ubuntu-26.04 -o json
```

**Diff the contents of two base images:**

```bash theme={null}
diff \
  <(nsc github base-image describe ubuntu-24.04 -o json) \
  <(nsc github base-image describe ubuntu-26.04 -o json)
```

## Arguments

### \<label>

The label of the base image to describe, for example `ubuntu-26.04`. Use [nsc github base-image list](/docs/reference/cli/github-base-image-list) to see the available labels.

## Optional Flags

<h3 id="-o---output-string">
  -o, --output string
</h3>

Output format. Default: `plain`.

Supported values: `plain`, `json`.

<h3 id="--canary">
  \--canary
</h3>

Fetch the canary/staging image instead of the production image.

## Related Topics

* [nsc github base-image list](/docs/reference/cli/github-base-image-list) - List available base images