It didn't work for me either, but there's a workaround in a case where your source is GitHub:

go-getter -mode=file https://raw.githubusercontent.com/hashicorp/go-getter/master/helper/url/url.go url.go

Or omitting -mode=file results in downloading the single file into a directory:

$ go-getter https://raw.githubusercontent.com/hashicorp/go-getter/master/helper/url/url.go test
2019/01/31 15:32:37 success!
$ tree test
test
└── url.go

0 directories, 1 file

I'm curious, is there a technical limitation that is preventing this?

I found that you can use go-getter to download a file from a github repo as long as the file is in the root and you force it to use ssh. Subdirectories don't seem to work (I think it might be a bug in the code).

The downside of this is go-getter clones the entire repo into a temp directory and only copies the file to the destination

$ go-getter -mode=file git@github.com:hashicorp/go-getter.git/README.md test/README.md
2021/07/11 15:42:56 success!

$ file test/README.md
test/README.md: ASCII text, with very long lines

Subdirectory...

$ go-getter -mode=file git@github.com:hashicorp/go-getter.git/helper/url/url.go test/url.go
2021/07/11 15:44:56 Error downloading: /usr/local/bin/git exited with 128: Cloning into '/var/folders/hw/6rsc6cbj5nddyhgfbwpdc5z80000gn/T/getter238570144/temp'...
fatal: remote error:
  hashicorp/go-getter.git/helper/url is not a valid repository name
  Visit https://support.github.com/ for help

# let's try with the subdirectory syntax
$ go-getter -mode=file git@github.com:hashicorp/go-getter.git//helper/url/url.go test/url.go
2021/07/11 15:45:05 Error downloading: /usr/local/bin/git exited with 128: Cloning into '/var/folders/hw/6rsc6cbj5nddyhgfbwpdc5z80000gn/T/getter520566758/temp'...
ERROR: Repository not found.
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

Hope this helps

Created a fork that fixes this issue at arikkfir/go-getter (see branches support_getfile_from_github and support_getfile_from_github_v2)
Opened two corresponding PRs in this repo with the fix & tests; see #355 and #356

I've run into this issue and was curious if we can expect fix being merged upstream at some point. The only difference is that this issue isnt isolated to the github getter for us.

For anyone who needs a stable release that incorporates this, I've created releases in my fork arikkfir/go-getter, based on the current releases v2.0.2 and v2.1.0:

• v.2.0.2+arikkfir
• v.2.1.0+arikkfir

The release notes include instructions on how to use them (single-liner to your go.mod file).

For the go-getter team - would be great to get #355 and #356 merged so the main releases provide this capability.

Any news?