Use pv to show progress bar during import-db

[longwave]

The Problem/Issue/Bug:

There is no feedback during long running database imports.

How this PR Solves The Problem:

This PR uses pv instead of cat to read the database dump which provides a progress bar on stderr.

Manual Testing Instructions:

• Import a (preferably large) database dump file with ddev import-db and check that a progress bar is displayed.
• Import a database dump with ddev import-db -p=false and check the progress bar is hidden.

Automated Testing Overview:

Changes are visual only, and require a tty, so automated testing is quite tricky.

Related Issue Link(s):

Fixes #1348

Release/Deployment notes:

Automated processes that use ddev import-db should not be affected as we detect presence of a tty and disable the progress bar in these environments. There is also the -p=false switch to disable the progress bar if needed.

[CLAassistant]

All committers have signed the CLA.

[longwave]

The tests fail because they are not connected to a tty, so it looks like I need to use github.com/mattn/go-isatty to detect whether stdout is a tty or not, and call Exec or ExecWithTty as appropriate. This might also be a good point to add a switch to disable progress even if the tty is present.

[rfay]

You're awesome, thanks for the PR! Ambitious!

[longwave]

A followup PR could refactor away ExecWithTty as Exec now has a tty option, and only the ssh command uses ExecWithTty.

[rfay]

Assuming this is just a test issue, happy to help when and if you're ready for help.

[longwave]

Any review comments or help with test fixes would be appreciated. I don't have time to look at this again until next year now.

[longwave]

@rfay The lint and compile steps seem to be working but it looks like the CircleCI tests don't rebuild the container images, so pv is not available during the tests?

[rfay]

What we have to do is push a new version of the container, and update in pkg/version/version.go with the new version. I just pushed drud/ddev-dbserver:20190103_import-db-progress-10.1 and drud/ddev-dbserver:20190103_import-db-progress-10.2, please add a commit to pkg/version/version.go that updates the version there (temporarily, until next release), and then you'll get the right container.

[longwave]

@rfay I can't see the buildkite results so don't know why the Windows builds have failed. The dockerforwindows one is especially suspicious at only 2 seconds runtime.

[rfay]

I've got those tests restarted for you, looks like you're mighty close!

Thanks for the awesome work on this. I'm looking forward to taking a look at it.

[rfay]

I rebased and tested this with a largish db on macOS; it worked fine with both ddev import-db and ddev pull. It may be that ddev pull needs the progressOption arg as well? But think we're good to go when it gets through the last round of tests.

[rfay]

You're awesome, thanks so much for this excellent contribution @longwave - I like it!