数据卷相对路径必须以 . 或 .. 开头，否则会被认为是卷名称，由于存在 “/” 会提示：ERROR: haproxy/haproxy.cfg includes invalid characters for a local volume name, only [a-zA-Z0-9][a-zA-Z0-9_.-] are allowed
参考来源：https://docs.docker.com/compose/compose-file/
You can mount a relative path on the host, which will expand relative to the directory of the Compose configuration file being used. Relative paths should always begin with . or ...
Resolve error below:
Step 5 : RUN apt-get install -y openssh-server apache2 supervisor
---> Running in 816b405cf0d1
Reading package lists...
Building dependency tree...
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
apache2 : Depends: apache2-mpm-worker (= 2.2.22-1ubuntu1) but it is not going to be installed or
apache2-mpm-prefork (= 2.2.22-1ubuntu1) but it is not going to be installed or
apache2-mpm-event (= 2.2.22-1ubuntu1) but it is not going to be installed or
apache2-mpm-itk (= 2.2.22-1ubuntu1) but it is not going to be installed
Depends: apache2.2-common (= 2.2.22-1ubuntu1) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
The command '/bin/sh -c apt-get install -y openssh-server apache2 supervisor' returned a non-zero code: 100
