大厅：无法连接到 unix:///var/run/docker.sock 处的 Docker 守护程序。 docker 守护程序是否正在运行？

Question

I'm working on creating a docker image inside docker container and push it to the docker hub using the Concourse CI tool.

I wrote the following shell script when it comes to docker build it throws the following error:

Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

ps I'm not trying to run docker-in-docker I just want to build an image

    #!/bin/bash

    apt-get update && apt-get install -y \
            bash    \
            sudo    \
            ca-certificates \
            make    \
            openssl \
            iputils-ping    \
            curl    \
            wget    \
            vim     \
            gnupg

    sudo apt-get update

    # install a few prerequisite packages which let apt use packages over HTTPS
    sudo apt-get install apt-transport-https ca-certificates curl software-properties-common -y

    # add the GPG key for the official Docker repository to your system
    curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

    # add the Docker repository to APT sources:
    sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu bionic stable" -y

    # update the package database with the Docker packages from the newly added repo:
    sudo apt update

    # make sure to install from the Docker repo instead of the default Ubuntu repo:
    apt-cache policy docker-ce

    # install Docker
    sudo apt-get install docker-ce -y

    # update one last time
    sudo apt update

    docker -v

    sudo service docker start

    # Build the image from Dockerfile
    docker build -f pipelines-repo/tasks/docker-image-update/ubuntu-base-with-docker/base.dockerfile -t myrepo/ubuntu-base-with-docker .

    # Login into Docker Hub
    echo ${DOCKER_HUB_PWD} | docker login --username=${DOCKER_HUB_UNAME} --password-stdin

    # Push the latest built image to Docker Hub
    docker push myrepo/ubuntu-base-with-docker:latest

Answer 1

In order to build an image inside a container, the docker program need to communicate with a docker daemon.

Usually it's done by mounting the host's socket file to the build container by running it with -v /var/run/docker.sock:/var/run/docker.sock