# Available runtimes
<a name="available-runtimes"></a>

You can specify one or more runtimes in the `runtime-versions` section of your buildspec file. If your runtime is dependent upon another runtime, you can also specify its dependent runtime in the buildspec file. If you do not specify any runtimes in the buildspec file, CodeBuild chooses the default runtimes that are available in the image you use. If you specify one or more runtimes, CodeBuild uses only those runtimes. If a dependent runtime is not specified, CodeBuild attempts to choose the dependent runtime for you. 

**Note**  
If a runtime version is not specified, CodeBuild uses the default version. The default version can change when a previously default version reaches end of life (EOL). To avoid unexpected changes to the build environment, we recommend specifying a runtime version in the buildspec file.

 For more information, see [Specify runtime versions in the buildspec file](build-spec-ref.md#runtime-versions-buildspec-file).

[Specify runtime versions in the buildspec file](build-spec-ref.md#runtime-versions-buildspec-file).

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**Topics**
+ [

## Linux image runtimes
](#linux-runtimes)
+ [

## macOS image runtimes
](#macOS-runtimes)
+ [

## Windows image runtimes
](#windows-runtimes)

## Linux image runtimes
<a name="linux-runtimes"></a>

The following table contains the available runtimes and the standard Linux images that support them. 


**Ubuntu and Amazon Linux platform runtimes**  
[\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/codebuild/latest/userguide/available-runtimes.html)

## macOS image runtimes
<a name="macOS-runtimes"></a>

**Important**  
The CodeBuild curated images for Mac builds contain macOS and Xcode pre-installed. By using the Xcode software, you acknowledge, understand, and consent to the [Xcode and Apple SDKs Agreement](https://www.apple.com/legal/sla/docs/xcode.pdf). If you do not accept the terms and conditions of the agreement, do not use the Xcode software. Instead, provide your own Amazon Machine Images (AMI). For more information, see [How do I configure a reserved capacity macOS fleet?](fleets.md#fleets.configure-macos)

The following table contains the available runtimes supported by macOS.


**macOS platform runtimes**  
[\[See the AWS documentation website for more details\]](http://docs.aws.amazon.com/codebuild/latest/userguide/available-runtimes.html)

## Windows image runtimes
<a name="windows-runtimes"></a>

The base image of the Windows Server Core 2019 contains the following runtimes.


**Windows platform runtimes**  

| Runtime name | Windows Server Core 2019 standard:1.0 versions | Windows Server Core 2019 standard:2.0 versions | Windows Server Core 2019 standard:3.0 versions | 
| --- | --- | --- | --- | 
| dotnet | 3.15.0 | 3.16.07.0 | 8.0 | 
| dotnet sdk | 3.15.0 | 3.16.07.0 | 8.0 | 
| golang | 1.14 | 1.18 | 1.211.221.23 | 
| gradle | 6.7 | 7.6 | 8.12 | 
| java | Corretto11 | Corretto11Corretto17 | Corretto8Corretto11Corretto17Corretto21 | 
| maven | 3.6 | 3.8 | 3.9 | 
| nodejs | 14.15 | 16.19 | 20.1822.13 | 
| php | 7.4 | 8.1 | 8.38.4 | 
| powershell | 7.1 | 7.2 | 7.4 | 
| python | 3.8 | 3.10 | 3.103.113.123.13 | 
| ruby | 2.7 | 3.1 | 3.23.33.4 |