docker - 如何从容器内部运行podman？

Question

我想将podman作为运行CI/CD管道的容器运行。但是，我不断从podman容器中收到此错误:

$ podman info
ERRO[0000] 'overlay' is not supported over overlayfs
Error: could not get runtime: 'overlay' is not supported over overlayfs: backing file system is unsupported for this graph driver

我正在使用 Jenkins Kubernetes plugin编写在Kubernetes集群中作为容器运行的CI/CD管道。我已经成功编写了使用Docker-in-Docker容器运行 docker build和 docker push命令的管道。

但是，在容器中运行Docker客户端和Docker Daemon会使CI/CD环境变得非常膨胀，难以配置，并且不适合使用。因此，我认为可以使用 podman从Dockerfiles构建Docker镜像，而无需使用胖Docker守护程序。

问题在于 podman 太新了，以至于我以前从未见过有人尝试过这样做，也没有足够的Podman专家来正确执行此操作。

因此，使用 podman installation instructions for Ubuntu创建了以下Dockerfile:

FROM ubuntu:16.04

RUN apt-get update -qq \
    && apt-get install -qq -y software-properties-common uidmap \
    && add-apt-repository -y ppa:projectatomic/ppa \
    && apt-get update -qq \
    && apt-get -qq -y install podman

# To keep it running
CMD tail -f /dev/null

因此，我构建了图像并按如下所示运行它:

# Build
docker build -t podman:ubuntu-16.04 .

# Run
docker run --name podman -d podman:ubuntu-16.04

然后在正在运行的容器上运行此命令时，出现错误:

$ docker exec -ti podman bash -c "podman info"

ERRO[0000] 'overlay' is not supported over overlayfs
Error: could not get runtime: 'overlay' is not supported over overlayfs: backing file system is unsupported for this graph driver

我在装有Ubuntu 16.04的计算机上安装了podman，并运行了相同的 podman info命令，得到了预期的结果:

host:
  BuildahVersion: 1.8-dev
  Conmon:
    package: 'conmon: /usr/libexec/crio/conmon'
    path: /usr/libexec/crio/conmon
    version: 'conmon version , commit: '
  Distribution:
    distribution: ubuntu
    version: "16.04"
  MemFree: 2275770368
  MemTotal: 4142137344
  OCIRuntime:
    package: 'cri-o-runc: /usr/lib/cri-o-runc/sbin/runc'
    path: /usr/lib/cri-o-runc/sbin/runc
    version: 'runc version spec: 1.0.1-dev'
  SwapFree: 2146758656
  SwapTotal: 2146758656
  arch: amd64
  cpus: 2
  hostname: jumpbox-4b3620b3
  kernel: 4.4.0-141-generic
  os: linux
  rootless: false
  uptime: 222h 46m 33.48s (Approximately 9.25 days)
insecure registries:
  registries: []
registries:
  registries:
  - docker.io
store:
  ConfigFile: /etc/containers/storage.conf
  ContainerStore:
    number: 0
  GraphDriverName: overlay
  GraphOptions: null
  GraphRoot: /var/lib/containers/storage
  GraphStatus:
    Backing Filesystem: extfs
    Native Overlay Diff: "true"
    Supports d_type: "true"
    Using metacopy: "false"
  ImageStore:
    number: 15
  RunRoot: /var/run/containers/storage
  VolumePath: /var/lib/containers/storage/volumes

有谁知道我该如何解决该错误并使Podman从容器中工作？

Answer 1

您的Dockerfile也应该安装iptables:

FROM ubuntu:16.04

RUN apt-get update -qq \
    && apt-get install -qq -y software-properties-common uidmap \
    && add-apt-repository -y ppa:projectatomic/ppa \
    && apt-get update -qq \
    && apt-get -qq -y install podman \
    && apt-get install -y iptables

# To keep it running
CMD tail -f /dev/null

然后使用以下命令运行命令:

docker run -ti --rm podman:test bash -c "podman --storage-driver=vfs info"

这应该给您您期望的答复。