I would like to ask you for a help/advice with the following issue. We are using Bamboo as our CI and we have remote bamboo agents running on k8s.

In our build we have step that creates a Docker image when tests ran correctly. To remote bamboo agents we are exposing Docker via docker.socket. When we had only one remote bamboo agent (to test how it works) everything was working correctly but recently we have increased the number of remote agents. Now it happen quite oft that a build gets stuck in docker image build step and will not move. We have to stop the build and run it again. Usually in logs is no useful info, but once in while this will appear.

24-May-2017 16:04:54 Execution failed for task ':...'.
24-May-2017 16:04:54 > Docker execution failed
24-May-2017 16:04:54 Command line [docker build -t ...] returned:
24-May-2017 16:04:54 time="2017-05-24T16:04:54+02:00" level=info msg="device or resource busy"

This how our k8s deployment looks like:

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: bamboo-agent
  namespace: backend-ci
spec:
  replicas: 5
  template:
    metadata:
      labels:
        app: bamboo-agent
    spec:
      containers:
      - name: bamboo-agent
        stdin: true
        resources:
          .
        env:
          .
          .
          .
        ports:
        - .
        volumeMounts:
          - name: dockersocket
            mountPath: /var/run/docker.sock
      volumes:
        - hostPath:
            path: /var/run/docker.sock
          name: dockersocket

And here is Dockerfile for remote bamboo agent.

FROM java:8

ENV CI true

RUN apt-get update && apt-get install -yq curl && apt-get -yqq install docker.io && apt-get install tzdata -yq
RUN curl -LO https://storage.googleapis.com/kubernetes-release/release/$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)/bin/linux/amd64/kubectl && chmod +x kubectl && mv kubectl /usr/local/bin
RUN echo $TZ | tee /etc/timezone 
RUN dpkg-reconfigure --frontend noninteractive tzdata
RUN wget -O /usr/local/bin/dumb-init https://github.com/Yelp/dumb-init/releases/download/v1.2.0/dumb-init_1.2.0_amd64
RUN chmod +x /usr/local/bin/dumb-init

ADD run.sh /root
ADD .dockercfg /root
ADD config /root/.kube/
ADD config.json /root/.docker/
ADD gradle.properties /root/.gradle/
ADD bamboo-capabilities.properties /root

ENTRYPOINT ["/usr/local/bin/dumb-init", "--"]

CMD /root/run.sh

Is there some way how to solve this issue? And is exposing docker.socket a good solution or is there some better approach?

I have read few articles about Docker in docker but I do not like --privileged mode.

If you need some other information I will try to provide them.

Thank you.