错误：File contains parsing errors: file:///etc/yum.repos.d/docker-ce.repo
[line 84]: docker-ce-nightly-source]
Because before installing docker, but not installed successfully, some residual files left on the system, the impact of the yum command, resulting in failure.
Solution:
You can delete this file /etc/yum.repos.d/docker-ce.repo
Source: Liu Juntao's blog
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