Bug 1414625

Description of problem:
Try the new Metrics install way using Ansible, failed at step task TASK [openshift_metrics : generate htpasswd file for hawkular metrics] *********
task path: openshift-ansible/roles/openshift_metrics/tasks/generate_hawkular_certificates.yaml:31
Form the log we can see it's caused by command 'htpasswd' is not available on master.
We should check it and install package 'httpd-tools' or in the document let user to install this package as prerequisite.

Version-Release number of selected component (if applicable):
openshift v3.5.0.5+8f2840d

How reproducible:
always

Steps to Reproduce:
1. prepare the inventory file

[oo_first_master]
$MASTER ansible_user=root ansible_ssh_user=root ansible_ssh_private_key_file="/home/penli/.ssh/libra.pem" openshift_public_hostname=$MASTER

[oo_first_master:vars]
deployment_type=openshift-enterprise
openshift_release=v3.5.0
openshift_metrics_install_metrics=true

openshift_metrics_hostname=hawkular-metrics.$SUBDOMAIN
openshift_metrics_project=openshift-infra

openshift_metrics_image_prefix=registry.ops.openshift.com/openshift3/
openshift_metrics_image_version=3.5.0

2. git clone https://github.com/openshift/openshift-ansible.git

3. ansible-playbook -vvv -i ~/inventory   playbooks/common/openshift-cluster/openshift_metrics.yml

4. task fail and abort.
message
fatal: [$MASTER]: FAILED! => {
    "changed": true, 
    "cmd": "htpasswd -ci '/etc/origin/master/metrics/hawkular-metrics.htpasswd' hawkular < '/etc/origin/master/metrics/hawkular-metrics.pwd'", 
    "delta": "0:00:00.003536", 
    "end": "2017-01-18 21:02:16.384476", 
    "failed": true, 
    "invocation": {
        "module_args": {
            "_raw_params": "htpasswd -ci '/etc/origin/master/metrics/hawkular-metrics.htpasswd' hawkular < '/etc/origin/master/metrics/hawkular-metrics.pwd'", 
            "_uses_shell": true, 
            "chdir": null, 
            "creates": null, 
            "executable": null, 
            "removes": null, 
            "warn": true
        }, 
        "module_name": "command"
    }, 
    "rc": 127, 
    "start": "2017-01-18 21:02:16.380940", 
    "stderr": "/bin/sh: htpasswd: command not found", 
    "stdout": "", 
    "stdout_lines": [], 
    "warnings": []
}

Expected results:
install successfully.

Additional info:
Ansible execution log attached.