RHEL7: "leapp preupgrade" fails with message "Failed to synchronize cache for repo"

Environment

• Red Hat Enterprise Linux 7.9
  • leapp
  • proxy

Issue

• leapp preupgrade fails with below error when system is registered to Red Hat customer portal using RHSM:

  Unable to install RHEL 8 userspace packages.
  'dnf', 'install', '-y', '--nogpgcheck', '--setopt=module_platform_id=platform:el8', '--setopt=keepcache=1', '--releasever', u'8.4', '--installroot', '/el8target', '--disablerepo', '*', '--enablerepo', u'rhel-8-for-x86_64-baseos-rpms', '--enablerepo', u'rhel-8-for-x86_64-appstream-rpms', 'dnf'] failed with exit code 1.
          Failed to synchronize cache for repo 'rhel-8-for-x86_64-appstream-rpms', ignoring this repo.
          Failed to synchronize cache for repo 'rhel-8-for-x86_64-baseos-rpms', ignoring this repo.
          Error: Unable to find a match: dnf
  

Resolution

• If the system is registered to Satellite then refer

• Check if the system is behind proxy. If yes then add proxy details in /etc/rhsm/rhsm.conf file.

  # an http proxy server to use
  proxy_hostname =
  
  # port for http proxy server
  proxy_port =
  

• The following fields are also required when using an authenticated proxy:

  # user name for authenticating to an http proxy, if needed
  proxy_user =
  
  # password for basic http proxy auth, if needed
  proxy_password =
  

• unset proxy environment variables :

  # unset http_proxy
  # unset https_proxy
  

Root Cause

• proxy is configured via http_proxy/https_proxy environment variables due to which leapp is unable to connect to RHEL 8 repositories for the upgrade. leapp refers /etc/rhsm/rhsm.conf file for the proxy configuration.

Diagnostic Steps

• Check /var/log/rhsm/rhsm.log

  # cat  /var/log/rhsm/rhsm.log 
  

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