Add [docker] in ubuntu-slim

[D3vil0p3r]

Tool name

docker

Tool license

Apache-2.0

Add or update?

• Add
• Update

Desired version

latest

Approximate size

No response

Brief description of tool

I would like to ask if it's possible to add docker to ubuntu-slim. The reason of this is because several users would like to use:

jobs:
  foobar:
    runs-on: ubuntu-slim
    container:
      image: mycontainer/base-devel:latest

but container rule cannot be run because in ubuntu-slim docker is not installed.

Currently docker is only in ubuntu-2x.xx and ubuntu-latest but we'd not use them because they have a lot of bloatware and only waste space, like:

• .NET
• Android SDK
• Java
• Swift
• Haskell
• Rust
• Julia
• ...

so, several of our jobs will failed due to no space left on device because most of it is occupied by software that are not usually used all together, resulting in bloatware.

ubuntu-slim with docker can solve this issue and allows us to use efficiently the space we need and allow the usage of:

    container:
      image: mycontainer/base-devel:latest

entries.

We cannot install docker by apt in steps section, otherwise container: and image: entries cannot be used anymore.

Some of us cannot use self-hosted solution because we don't have remote servers where to host our custom runners and we would like to use GitHub resources efficiently.

Thank you for understanding.

URL for tool's homepage

https://www.docker.com/

Provide a basic test case to validate the tool's functionality.

Platforms where you need the tool

• Azure DevOps
• GitHub Actions

Runner images where you need the tool

• Ubuntu 22.04
• Ubuntu 24.04
• Ubuntu Slim
• macOS 14
• macOS 14 Arm64
• macOS 15
• macOS 15 Arm64
• macOS 26 Arm64
• Windows Server 2019
• Windows Server 2022
• Windows Server 2025

Can this tool be installed during the build?

Tool installation time in runtime

Seconds

Are you willing to submit a PR?

No response

[erik-bershel]

We'll consider your request, but we'll likely have to refuse. The Ubuntu Slim agent is already a container, and I'm not sure the architectural support for Docker-in-Docker on the host outweighs the maintenance concerns.

[D3vil0p3r]

Thank you for the clarification. I agree that ubuntu-slim being container-based means supporting jobs.<job>.container would require privileged or Docker-in-Docker–style plumbing.

My request is less about Docker itself and more about feature parity: today, the container: / image: job syntax is a first-class, documented feature of GitHub Actions that works on VM-based runners like ubuntu-latest. From a user perspective, it’s surprising that the same syntax is unavailable on ubuntu-slim, even if enabling it requires additional privileges or opt-in constraints.

I understand the maintenance, but I believe there may still be value in offering this as an explicit, documented capability (or limitation), rather than a silent incompatibility.

[erik-bershel]

My request is less about Docker itself and more about feature parity: today, the container: / image: job syntax is a first-class, documented feature of GitHub Actions that works on VM-based runners like ubuntu-latest. From a user perspective, it’s surprising that the same syntax is unavailable on ubuntu-slim, even if enabling it requires additional privileges or opt-in constraints.

I understand the maintenance, but I believe there may still be value in offering this as an explicit, documented capability (or limitation), rather than a silent incompatibility.

Valid point. 💯