JenkinsでDockerをつかえるように

jenkins.Dockerfile

FROM jenkins/jenkins:lts
# Install plugins
COPY ./plugins.txt /usr/share/jenkins/ref/plugins.txt
RUN /usr/local/bin/install-plugins.sh < /usr/share/jenkins/ref/plugins.txt

USER root

RUN apt-get update
##### Docker install START >>>
# 前提ソフトウェアのインストール
RUN apt-get install -y apt-transport-https ca-certificates curl gnupg-agent software-properties-common

RUN curl -fsSL https://download.docker.com/linux/debian/gpg | apt-key add -

RUN apt-key fingerprint 0EBFCD88
RUN add-apt-repository \
    "deb [arch=amd64] https://download.docker.com/linux/debian \
    $(lsb_release -cs) \
    stable"
RUN apt-get update
RUN apt-get install -y docker-ce docker-ce-cli containerd.io
RUN usermod -g docker jenkins
USER jenkins
##### <<< Docker install END