[WIP] Add a new Docker communicator

[loicalbertin]

Hi all

This PR is based on issue #4686.

The idea is to allow post-creation configuration for a Docker container using file upload and remote command execution.
This PR leverage the docker remote API to do it via the github.com/fsouza/go-dockerclient dependency

Please be tolerant as this is my very first time in Go. Any suggestions/improvements are welcome.

What's currently working:

• File upload through docker or null resources
• Non interactive remote command execution through docker or null resources
• Docker connector is the default one for docker_container resources

What's currently not working:

• I was not able to use the AttachStdin feature of the docker API I did many tests and it is still not working. Could someone have a look on this to help me?

What's may need improvements:

• In the tar generation function for a single file I have to read the whole file to have its size (see my TODO comment). Is there a better way to do it?
• For single file upload (also used for inline scripts) I arbitrarily set file permissions to 700 (useful for later executing this file). Maybe it could be interesting to expose a configuration parameter for this?

Thanks for your feedback.

[mildwonkey]

Hello! In an effort to address old PRs, I am going to close this one as it's labeled [WIP] and hasn't had any activity in quite awhile. If this is still something you would like to see or work on, please open a new PR (or feature request, if there isn't one already). Thanks!

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.