🚀 v2.8.2 is out, with EFS, Ephemeral Registry support, and YOLO mode (tmpfs)!

Speed up docker builds with the ephemeral registry, share files across workflow jobs with EFS, and speed up your builds with tmpfs!

May 15, 2025

Check out the new documentation pages for:

Now for the full release notes:

Details

Released on: 2025-05-15T07:36:53Z.
For more details: view release notes on GitHub.
CloudFormation template: https://runs-on.s3.eu-west-1.amazonaws.com/cloudformation/template-v2.8.2.yaml

Summary

Support for EFS, TMPFS, and ECR ephemeral registry for fast docker builds. Also some bug fixes.

What's changed

EFS

Embedded networking stack can now create an Elastic File System (EFS), and runners will auto-mount it at /mnt/efs if the extras label include efs. Useful to share artefacts across job runs, with classic filesystem primitives.

jobs:
  with-efs:
    runs-on: runs-on=${{ github.run_id }},runner=2cpu-linux-x64,extras=efs
    steps:
      - run: df -ah /mnt/efs
      # 127.0.0.1:/      8.0E   35G  8.0E   1% /mnt/efs

📝 Example use case for maintaining mirrors

For instance this can be used to maintain local mirrors of very large github repositories and avoid long checkout times for every job:

env:
  MIRRORS: "https://github.com/PostHog/posthog.git"
  # can be ${{ github.ref }} if same repo as the workflow
  REF: main

jobs:
  with-efs:
    runs-on: runs-on=${{ github.run_id }},runner=2cpu-linux-x64,extras=efs
    steps:
      - name: Setup / Refresh mirrors
        run: |
          for MIRROR in ${{ env.MIRRORS }}; do
            full_repo_name=$(echo $MIRROR | cut -d/ -f4-)
            MIRROR_DIR=/mnt/efs/mirrors/$full_repo_name
            mkdir -p "$(dirname $MIRROR_DIR)"
            test -d "${MIRROR_DIR}" || git clone --mirror ${MIRROR/https:\/\//https:\/\/x-access-token:${{ secrets.GITHUB_TOKEN }}@} "${MIRROR_DIR}"
            ( cd "$MIRROR_DIR" && \
              git remote set-url origin ${MIRROR/https:\/\//https:\/\/x-access-token:${{ secrets.GITHUB_TOKEN }}@} && \
              git fetch origin ${{ env.REF }} )
          done
      - name: Checkout from mirror
        run: |
          git clone file:///mnt/efs/mirrors/PostHog/posthog.git --branch ${{ env.REF }} --single-branch --depth 1 upstream

Ephemeral registry

Support for an Ephemeral ECR registry: can now automatically create an ECR repository that can act as an ephemeral registry for pulling/pushing images and cache layers from your runners. Especially useful with the type=registry buildkit cache instruction. If the extras label includes ecr-cache, the runners will automatically setup docker credentials for that registry at the start of the job.

jobs:
  ecr-cache:
    runs-on: runs-on=${{ github.run_id }},runner=2cpu-linux-x64,extras=ecr-cache
    steps:
      - uses: actions/checkout@v4
      - uses: docker/setup-buildx-action@v3
      - uses: docker/build-push-action@v4
        env:
          TAG: ${{ env.RUNS_ON_ECR_CACHE }}:my-app-latest
        with:
          context: .
          push: true
          tags: ${{ env.TAG }}
          cache-from: type=registry,ref=${{ env.TAG }}
          cache-to: type=registry,ref=${{ env.TAG }} }},mode=max,compression=zstd,compression-level=22

Tmpfs

Support for setting up a tmpfs volume (size: 100% of available RAM, so only to be used on high-memory instances), and binding the /tmp, /home/runner, and /var/lib/docker folders on it. /tmp and /home/runner are mounted as overlays, preserving their existing content.

Can speed up some IO-intensive workflows. Note that if tmpfs is active, instances with ephemeral disks won't have those mounted since it would conflict with the tmpfs volume.

jobs:
  with-tmpfs:
    runs-on: runs-on=${{ github.run_id }},family=r7,ram=16,extras=tmpfs
    steps:
      - run: df -ah /mnt/tmpfs
      # tmpfs            16G  724K   16G   1% /mnt/tmpfs
      - run: df -ah /home/runner
      # overlay          16G  724K   16G   1% /home/runner
      - run: df -ah /tmp
      # overlay          16G  724K   16G   1% /tmp
      - run: df -ah /var/lib/docker
      # tmpfs            16G  724K   16G   1% /var/lib/docker

You can obviously combine options, i.e. extras=efs+tmpfs+ecr-cache+s3-cache is a valid label 😄

Instance-storage mounting changes

Until now, when an instance has locally attached NVMe SSDs available, they would be automatically formatted and mounted so that /var/lib/docker and /home/runner/_work directories would end up on the local disks. Since a lot of stuff (caches etc.) seem to end up within the /home/runner folder itself, the agent now uses the same strategy as for the new tmpfs mounts above (i.e. the whole /home/runner folder is mounted as an overlay on the local disk volume, as well as the /tmp folder. /var/lib/docker remains mounted as a normal filesystem on the local disk volume). Fixes #284.

Misc

Move all RunsOn-specific config files into /runs-on folder on Linux. More coherent with Windows (C:\runs-on), and avoids polluting /opt folder.
Fix app_version in logs (was previously empty string due to incorrect env variable being used in v2.8.1).
Fix "Require any Amazon EC2 launch template not to auto-assign public IP addresses to network interfaces" from AWS Control Tower. When the Private mode is set to only, no longer enable public ip auto-assignment in the launch templates. Thanks @temap!