Description of problem:
If install_type is not defined, exec defaults to false.
In cloud images for environment with limited network, it is common that the chef client packages are already present in the RHEL image.
./cloudinit/config/cc_chef.py
    force_install = util.get_cfg_option_bool(chef_cfg,
                                             'force_install', default=False)
    if not is_installed() or force_install:
        run = install_chef(cloud, chef_cfg, log)
    elif is_installed():
        run = util.get_cfg_option_bool(chef_cfg, 'exec', default=False)
    else:
        run = False
    if run:
        run_chef(chef_cfg, log)
        post_run_chef(chef_cfg, log)

This behaviour should either be documented or should be changed.

chef:
 install_type: "gems"
 exec: true

Version-Release number of selected component (if applicable):
all versions since chef option was available

How reproducible:
always

Steps to Reproduce:
1. Build an image with chef client.

2. Use this example or similar example which does not have install_type.
https://cloudinit.readthedocs.io/en/latest/topics/examples.html

3. 

Actual results:
chef does not run

Expected results:
chef client runs & performs the tasks.

Additional info: