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Handling Backup Actions

In this document, we will explain the process of handling different actions in the backup module. The process involves retrieving parameters, creating backups, and managing volume group backups.

The flow starts with retrieving the action and type parameters to determine the operation and backup type. If the action is 'create', additional parameters are retrieved to customize the backup creation. For 'savevg' type, it checks for necessary parameters and sets error messages if conditions are not met. The savevg function checks for existing backups and creates a new one if needed. The check_vg function ensures the volume group is active before proceeding with the backup.

Flow drill down​

Handling Different Actions​

First, the main function retrieves the action and type parameters from the module. These parameters determine what kind of operation (create, restore, view) and what type of backup (mksysb, savevg) will be performed.

    action = module.params['action']
    params['objtype'] = module.params['type']
    params['flags'] = module.params['flags']
    params['location'] = module.params['location']

Creating a Backup​

Next, if the action is 'create', additional parameters like verbose, create_data_file, exclude_fs, exclude_files, extend_fs, and force are retrieved. These parameters are used to customize the backup creation process.

    if action == 'create':
        params['verbose'] = module.params['verbose']
        params['create_data_file'] = module.params['create_data_file']
        params['exclude_fs'] = module.params['exclude_fs']
        params['exclude_files'] = module.params['exclude_files']
        params['extend_fs'] = module.params['extend_fs']
        params['force'] = module.params['force']

Handling 'savevg' Type​

Then, if the type is 'savevg', the function checks if the 'name' parameter is provided and if exclude_data is set when the name is 'rootvg'. If these conditions are not met, appropriate error messages are set, and the function fails.

        elif params['objtype'] == 'savevg':
            params['name'] = module.params['name']
            params['exclude_data'] = module.params['exclude_data']

            if not params['name']:
                results['msg'] = 'argument \'name\' is missing.'
                module.fail_json(**results)
            if params['exclude_data'] and params['name'] == 'rootvg':
                results['msg'] = 'name cannot be \'rootvg\'.'
                module.fail_json(**results)

Managing Volume Group Backups​

Moving to the savevg function, it first checks if a backup image already exists at the specified location. If a backup exists and the 'force' parameter is not set, it logs a message and returns without creating a new backup.

def savevg(module, params, vg):
    """
    Run the savevg command to back up files of a volume group.
    But first, checks the volume group is varied-on.

    arguments:
        module  (dict): the module variable
        params  (dict): the command parameters
        vg       (str): the volume group to back up
    return:
        rc       (int): the return code of the command
    """

    module.log(f'Creating VG backup of { vg } with savevg.')

    # Check if the backup image already exists
    if not params['force']:
        rc = restvg_view(module, params)
        # check if there is an existing backup specified by 'location' parameter
        # if there is not existing backup at 'location' then proceed to creation of backup
        # 0512-054 listvgbackup: File /tmp/testvg_backup does not exist or is empty.

Checking Volume Group Status​

Diving into the check_vg function, it checks if the specified volume group is active. If the volume group is not active, it logs an appropriate message and returns False, preventing the backup from proceeding.

def check_vg(module, vg):
    """
    Check if the volume group is active (i.e. varied-on).

    arguments:
        module  (dict): The Ansible module
        vg       (str): the volume group to back up
    return:
        True if the vg can be used
        False otherwise
    """

    module.log(f'Checking { vg } is active.')

    # list active volume groups
    cmd = ['/usr/sbin/lsvg', '-o']
    rc, stdout, stderr = module.run_command(cmd)
    if rc != 0:
        results['msg'] = f'Cannot get active volume group. Command \'{ cmd }\' failed.'
        results['stdout'] = stdout
        results['stderr'] = stderr

 

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