* removed packer.Cache and references since packer.Cache is never used except in the download step. The download step now uses the new func packer.CachePath(targetPath) for this, the behavior is the same.
* removed download code from packer that was reimplemented into the go-getter library: progress bar, http download restart, checksuming from file, skip already downloaded files, symlinking, make a download cancellable by context.
* on windows if packer is running without symlinking rights and we are getting a local file, the file will be copied instead to avoid errors.
* added unit tests for step_download that are now CI tested on windows, mac & linux.
* files are now downloaded under cache dir `sha1(filename + "?checksum=" + checksum) + file_extension`
* since the output dir is based on the source url and the checksum, when the checksum fails, the file is auto deleted.
* a download file is protected and locked by a file lock,
* updated docs
* updated go modules and vendors
/cc @andytson - Wanted to CC you in here so you could see some changes I
made.
First, I changed commit to opt-in, so you set "commit": true to get
commit behavior. This simplifies the logic a bit. Then, I removed the
skipping for StepExport and StepCommit and put that into the Builder
itself. This simplifies those steps (limits abstraction leakage).
Otherwise, everything looks great!
Megan Marsh
Adrien Delorme
Matthew Hooker
Orivej Desh
Chris Bednarski
Mitchell Hashimoto
Andy Thompson