Unset user-defined locale variables

[smortex]

Some commands used by the package module can localize the output to
match the user preferences. When matching the output string with a
Regexp to extract information, the pattern fails to be found and the
information is not correctly extracted:

  {
    "status": "install ok installed",
    "version": "7.24.0-1bullseye",
    "latest": ""
  }

In the above example, the shell on the target system has a fr_FR.UTF-8
locale, apt-cache policy puppet-agent returned:

puppet-agent:
  Installé : 7.24.0-1bullseye
  Candidat : 7.24.0-1bullseye
 Table de version :
 *** 7.24.0-1bullseye 500
        500 http://apt.puppetlabs.com bullseye/puppet7 amd64 Packages
        100 /var/lib/dpkg/status
     7.23.0-1bullseye 500
        500 http://apt.puppetlabs.com bullseye/puppet7 amd64 Packages
     7.21.0-1bullseye 500
        500 http://apt.puppetlabs.com bullseye/puppet7 amd64 Packages
     7.20.0-1bullseye 500
        500 http://apt.puppetlabs.com bullseye/puppet7 amd64 Packages
     7.19.0-1bullseye 500
        500 http://apt.puppetlabs.com bullseye/puppet7 amd64 Packages
     7.18.0-1bullseye 500
        500 http://apt.puppetlabs.com bullseye/puppet7 amd64 Packages
     7.17.0-1bullseye 500
        500 http://apt.puppetlabs.com bullseye/puppet7 amd64 Packages
     7.16.0-1bullseye 500
        500 http://apt.puppetlabs.com bullseye/puppet7 amd64 Packages
     7.15.0-1bullseye 500
        500 http://apt.puppetlabs.com bullseye/puppet7 amd64 Packages
     7.14.0-1bullseye 500
        500 http://apt.puppetlabs.com bullseye/puppet7 amd64 Packages
     7.13.1-1bullseye 500
        500 http://apt.puppetlabs.com bullseye/puppet7 amd64 Packages
     7.12.1-1bullseye 500
        500 http://apt.puppetlabs.com bullseye/puppet7 amd64 Packages
     7.12.0-1bullseye 500
        500 http://apt.puppetlabs.com bullseye/puppet7 amd64 Packages
     7.11.0-1bullseye 500
        500 http://apt.puppetlabs.com bullseye/puppet7 amd64 Packages
     7.10.0-1bullseye 500
        500 http://apt.puppetlabs.com bullseye/puppet7 amd64 Packages
     7.9.0-1bullseye 500
        500 http://apt.puppetlabs.com bullseye/puppet7 amd64 Packages

and grep 'Candidate:' found no match. Because the available version
is "" and is different from the installed one, it is reported with the
latest key.

Because we rely on mathing localized output, we must make sure to unset
variables that the shell we are running all might have set.

[bastelfreak]

interesting, what is LANG afterwards? Could we explicitly set LC_ALL=C?

[smortex]

LANG is unset after that 🙃.

I was not sure about forcing LC_ALL to C or C.UTF-8, then recalled that older FreeBSD versions do not support C.UTF-8 and that if the user used something else that UTF-8 with extended ASCII forcing UTF-8 would still break it. But maybe we can do better: we only need to change LC_MESSAGES to have messages in english, and for LC_*, the value is:

• The value of LC_ALL if set (highest priority);
• The value of LC_* if set;
• The value of LANG (lowest priority).

So, we can:

1. Copy LC_ALL in LANG if LANG is unset;
2. Unset LC_ALL
3. Set LC_MESSAGES to C

export LANG=${LANG:-$LC_ALL}
unset LC_ALL
export LC_MESSAGES=C

This should preserve a correct behavior for users of accented chars.

[smortex]

I adjusted the PR accordingly. I guess no packages have a name with accented char so this would not have caused trouble in the tasks of this module, but something makes me think this code should be part of Bolt itself and be run before running any shell scripts on remote systems…