Refactor backup_and_replace_hostname() into a flexible config modification tool
backup_and_replace_hostname() was doing three things:
1. Given config file in 'key=value' style, replace value for a
specified key (HOSTNAME)
2. Backup original file and install a replacement
3. Restore original security context after editing
We have several more places where parts of the functionality are needed,
thus making two tools in ipapython.ipautil:
1. config_replace_variables(filepath, replacevars=dict(),
appendvars=dict())
Replaces or appends values to specified keys, adding new key=value
pairs if key was absent
2. backup_config_and_replace_variables(fstore, filepath,
replacevars=dict(),
appendvars=dict())
Backups config file and calls config_replace_variables()
A caller must handle security context after using these two tools.
In addition, as before, there is
ipapython.services.backup_and_replace_hostname() that uses
these common tools and restores security context after editing.
The code will be used extensively for systemd integration for Fedora 16.
Fixes:
https://fedorahosted.org/freeipa/ticket/1871