title: Problem with moby packages when installing docker-ce on CentOS 7
body: <p>I have a docker image for CentOS 7 which installs docker-ce via the <a href="https://docs.docker.com/engine/install/centos/" rel="nofollow noreferrer">recommended instructions</a>.
  i.e.</p>
  <pre><code>RUN yum-config-manager \
    --add-repo \
  https://download.docker.com/linux/centos/docker-ce.repo
  RUN yum install -y yum-utils \
    device-mapper-persistent-data \
    lvm2
  RUN yum update -y
  RUN yum install -y docker-ce docker-ce-cli containerd.io
  </code></pre>
  <p>Recently this stopped working and now fails as follows:</p>
  <pre><code>--&gt; Processing Conflict: moby-containerd-1.3.6+azure-1.x86_64 conflicts containerd
  --&gt; Processing Conflict: moby-runc-1.0.0~rc10+azure-2.x86_64 conflicts runc
  --&gt; Finished Dependency Resolution
  Error: moby-containerd conflicts with containerd.io-1.2.13-3.2.el7.x86_64
  Error: moby-runc conflicts with containerd.io-1.2.13-3.2.el7.x86_64
   You could try using --skip-broken to work around the problem
   You could try running: rpm -Va --nofiles --nodigest
  The command '/bin/sh -c yum install -y docker-ce docker-ce-cli containerd.io' returned a non-zero code: 1
  </code></pre>
  <p>If the install command is replaced with:</p>
  <pre><code>yum install -y docker
  </code></pre>
  <p>I get a different error to do with an unsigned package:</p>
  <pre><code>Package runc is obsoleted by moby-runc, trying to install moby-runc-1.0.0~rc10+azure-2.x86_64 instead
  ...
  Package moby-runc-1.0.0~rc10+azure-2.x86_64.rpm is not signed
  </code></pre>
  <p>I tried forcing use of a few old versions as below to no avail e.g.</p>
  <pre><code>RUN yum install -y docker-1.13.1-102.git7f2769b.el7.centos
  </code></pre>
  <p>Why is this happening? How can I fix it? And how can I prevent similar problems in the future?</p>
  <hr />
  <p>Update: A critical missing piece of information from this question is the use of Azure. I had the following as aspnetcore is required to publish packages in an Azure devops pipeline:</p>
  <pre><code>RUN rpm -Uvh https://packages.microsoft.com/config/centos/7/packages-microsoft-prod.rpm
  RUN yum update -y &amp;&amp; yum install aspnetcore-runtime-3.1 -y
  </code></pre>