wiki:GEC21Agenda/ScalingUp/Procedure/Appendix

Version 24 (modified by sedwards@bbn.com, 4 years ago) (diff)

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Appendix: Installing software using the Ansible Configuration Management tool

Tools:

To run this exercise, you will need two pieces of software. If you haven't already, get or install these now:

  1. omni installed on your local machine (instructions), and
  2. ansible installed on your local machine (find the instructions for your package manager here).

    Windows users should have done the following steps before they reserved their resources.

    Tip Before reserving their resources, Windows users should have followed the instructions for setting up a separate GENI node for running Ansible.

Resources:

Instructions

1. Establish the Environment

  1. Download the Ansible playbook, webpages, etc needed to configure the nodes.

    Use wget to download the tarball of files onto your local machine and use tar to uncompress it:

    wget http://www.gpolab.bbn.com/experiment-support/XXXXX.tar.gz
    tar zxvf XXXXXX.tar.gz
    

2. Configure and Initialize

omni comes with a script, readyToLogin which finds the login information for nodes in your slice. As of omni version 2.8, readyToLogin has an --ansible-inventory flag which generates the Ansible inventory, which is a flat file which tells Ansible the name and login information for your nodes.

  1. Create your Ansible inventory file:

    On your local machine:

    $ readyToLogin MYSLICE --useSliceAggregates --ansible-inventory -o
    $ cat inventory
    

    Example output of running these commands:

    $ readyToLogin MYSLICE --useSliceAggregates --ansible-inventory -o
    Host info saved in inventory file: /Users/jdoe/projects/GENI/hellogeni/inventory
    
    $ cat inventory
    host-2  ansible_ssh_host=pc2.instageni.stanford.edu  ansible_ssh_port=31291
    host-1  ansible_ssh_host=pc2.instageni.stanford.edu  ansible_ssh_port=31290
    server-1  ansible_ssh_host=pcvm2-33.instageni.stanford.edu
    rt-1  ansible_ssh_host=pc2.instageni.stanford.edu  ansible_ssh_port=31292
    
    Tip Windows users should copy their 'inventory' file onto their node running the ansible client.
  2. Be sure your private key has been added to your SSH agent:
    ssh-add /path/to/your/private/key
    
  3. Check to see if your nodes are up and ready.

    This command uses the ping module to ping the specified nodes (in this case all) listed in the inventory file:

    $ ansible -i inventory all -m ping 
    

    Example output showing all of the nodes responding to ping:

    $ ansible -i inventory all -m ping 
    server-1 | success >> {
        "changed": false,
        "ping": "pong"
    }
    
    host-1 | success >> {
        "changed": false,
        "ping": "pong"
    }
    
    rt-1 | success >> {
        "changed": false,
        "ping": "pong"
    }
    
    host-2 | success >> {
        "changed": false,
        "ping": "pong"
    }
    
  4. Try using the ping module in Ansible to only ping server-1 or host-1 by replacing all in the above with server-1 or host-1.

3. Configure the nodes

Tip Ansible commands can be collected into files called Playbooks. Playbooks are in a configuration file format called YAML which is very straightforward. In particular, Ansible Ad Hoc commands easily map to commands used in an Ansible Playbook.

The Playbook to configure the server node is in server.yml. It links to other files. For example, the code to tell the server node to run an nmap scan and post the results is in roles/nmap/tasks/map.yml and looks as follows:

---
   - name: map network using nmap
     command: nmap -sP -oX {{ nmap_xml_file }} {{ address_range }}
   - name: convert nmap xml to html
     shell:  xsltproc /usr/share/nmap/nmap.xsl {{ nmap_xml_file }} > {{ nmap_html_file }}
   - name: create directory for nmap logs in WEB_ROOT/nmaplogs with permissions of 755
     file: >
        dest={{ WEB_ROOT }}/{{ nmap_dir }}
        state=directory
        mode=755
   - name: copy nmap html file to a public place
     command: mv {{ nmap_html_file }} {{ WEB_ROOT }}/{{ nmap_dir }}/nmap.html removes={{ nmap_html_file }}

Do these commands look like the Ad Hoc command (ping) from the previous step?

Run the playbook to configure the server with the following command on the local machine:

ansible-playbook server.yml -i inventory
  1. Browse to hostname of the server node in your browser. Click on the nmap link.

4. Update a portion of the configuration

  1. After some of your neighbors have brought up their nodes, run the following command to only update the nmap portion of the server configuration:
    ansible-playbook update-map.yml -i inventory
    
  2. If you repeatedly run the above command over time you should see more nodes found by the nmap scan.
  3. Change the value of address_range in groups_vars/all.yml and rerun update-map.yml to search for more nodes.