cloud-utils: depends on sed being available as gnused

[martijnvermaat]

Issue description

cloud-utils depends on the gnused binary being in $PATH, but stdenv has sed as just sed.

Steps to reproduce

$ nix-shell -p cloud-utils
$ growpart /dev/sda 1
# I assume this fails, reported by jeaye on IRC

Or just:

$ nix-shell -p cloud-utils --run 'gnused --version'
/run/user/1000/nix-shell.x2PKAC/rc: line 1: gnused: command not found

Technical details

• System: (NixOS: 16.03)
• Nix version: 1.11.2
• Nixpkgs version: unstable and master

Cause and proposed solution

In buildPhase, use of sed is replaced by gnused here. I traced that code back to this commit which also includes this line making sed available as gnused, but these are now separated in the codebase.

In amazon-grow-partition, cloud-utils is used in the original context (in initrd) where gnused is still explicitely made available, but of course this doesn't hold when using cloud-utils elsewhere.

It was mentioned on IRC by clever that using absolute paths instead of relying on PATH here would perhaps mess with the closure size of the initrd.

[martijnvermaat]

cc @domenkozar as you separated cloud-utils from amazon-grow-partition.

[chris-martin]

Please reopen, this is still a problem in NixOS 17.09.

# growpart /dev/xvda 1
/nix/store/hw5ydc3i92q686sb3yr275qihdhx2m5j-cloud-utils-0.29/bin/.growpart-wrapped: line 257: gnused: command not found
FAILED: gnused failed on dump output

[chris-martin]

There's a workaround here: #22211 (comment)

[orivej]

growpart from the cloud-utils package uses sed not gnused, which is added to the PATH in the wrapper.

[chris-martin]

@orivej I could be mistaken, but I don't think that's the case for the version of cloud-utils currently in NixOS release 17.09.

[domenkozar]

afaik this wasn't backported

[domenkozar]

there was a PR in master to fix it, but never backported.