= [wiki:GENIExperimenter/Tutorials/GENIExperimentEngine Get to Know the GENI Experiment Engine] = {{{ #!html
Hello GENI index Hello GENI index Hello GENI index
}}} ---- = STEPS FOR SETTING UP = ---- == 1. Get a GEE Slicelet and download GEE helper files == Visit http://gee-project.org and login. Once logged in, click on ''Get a slicelet''. Reload the dashboard every few seconds until the slice is in state ''Running'' -- this should take about 30 seconds. Then click on ''Download Slicelet File'' to download the GEE helper files. Unpack the tarball and take a look at '''README.txt'''. ---- == 2. Learn about GEE networking == Pick a node from your '''ssh-config''' file and log in to it with SSH. For example: {{{ $ ssh -i id_rsa -F ssh-config slice338.pcvm3-1.instageni.metrodatacenter.com }}} Type '''ifconfig eth0'''. You should see an eth0 interface with an IP address in the 10.0.0.0/8 range, a ''private'' IP address. {{{ root@slice347:~# ifconfig eth0 eth0 Link encap:Ethernet HWaddr a6:24:c1:df:c7:09 inet addr:10.20.0.243 Bcast:0.0.0.0 Mask:255.255.0.0 inet6 addr: fe80::a424:c1ff:fedf:c709/64 Scope:Link UP BROADCAST RUNNING MTU:1500 Metric:1 RX packets:56555 errors:0 dropped:2 overruns:0 frame:0 TX packets:49525 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:93890170 (93.8 MB) TX bytes:8052865 (8.0 MB) }}} This IP address is behind a NAT and not directly reachable from outside (i.e., from the Internet). However all nodes in your slicelet can contact each other using the private addresses. The nodes in your '''ssh-config''' file are Docker containers running on (virtual) hosts. These hosts have ''public'' IP addresses that are routable from the Internet, that's why you can login to the Docker containers of your slicelet. A port on the public IP address (e.g., 49155) is forwarded to the SSH port (22) on the container's private IP address. The '''ssh-config''' file contains the names of the virtual hosts and the port forwarding information. When you run a server on a node in your slicelet, it will listen on the private address, because that is the only one it can see. By default it will only be visible to other nodes in your slicelet. Docker provides facilities for exposing ports to the public Internet, but this topic is outside the scope of this tutorial. ''Note that later on you will need to find both the ''public'' and ''private'' IP addresses for each node in the slicelet.'' ---- == 3. Configure the Ansible controller for your slicelet == If you already have Ansible installed on your laptop, then you can use it as the controller for this experiment. Otherwise, you will use one of the nodes in your slicelet as the Ansible controller. Pick one, log into it, and install ansible using apt-get: {{{ $ apt-get update $ apt-get install ansible }}} Then upload your slicelet helper files to that node. {{{scp}}} can be used for this {{{ $ scp -i id_rsa -F ssh-config ansible-hosts slice323.pcvm3-1.instageni.metrodatacenter.com:. $ scp -i id_rsa -F ssh-config id_rsa slice323.pcvm3-1.instageni.metrodatacenter.com:. }}} || [[Image(wiki:GENIExperimenter/Tutorials/Graphics:tip.png, nolink, 50px, bottom)]] || '''Pro Tip:''' remove your controller node from the '''ansible_hosts''' file after you’ve uploaded. || ---- == 4. Learn some basic concepts of Ansible == Ansible (http://docs.ansible.com) is a free, open-source, intuitive IT automation tool that is well-suited to the tasks in this tutorial. Ansible commands can be run from the command line or put in a YAML file called a ''playbook''. We will be creating an Ansible playbook to run the parameterized HTTP query described earlier. Two basic concepts in Ansible are ''inventories'' and ''modules''. An inventory is a list of hosts to be managed by Ansible, organized into groups. When you run Ansible commands, either from the command-line or in a playbook, you specify the host group that the command should operate on. In this way Ansible commands can operate on many hosts in parallel. Take a look at the Ansible inventory in your '''ansible-hosts''' file. This is basically the equivalent of the '''ssh-config''' except its specialized for Ansible. A ''task'' in Ansible consists of a module and some arguments for the module. A module provides a declarative abstraction on top of standard shell commands. So for example, in the shell on an Ubuntu machine you might install package “foo” like this: {{{ $ sudo apt-get update $ sudo apt-get install foo }}} An equivalent Ansible task in a playbook would look like: {{{ - apt: name=foo state=latest update_cache=yes }}} Or the same Ansible task could be invoked directly on the command line like this: {{{ $ ansible remote-machine -m apt -a "name=foo state=latest update_cache=yes" }}} The task uses the '''apt''' module, and tells Ansible: “Make sure the latest version of package foo is installed”. There are many other modules which are well-documented at http://docs.ansible.com. Here are a few Ansible tasks to run, to get some experience with the command-line interface. === (a) The ping module === The '''ping''' module simply tries to do a SSH login to a node and reports success or failure. Run the following command on your controller: {{{ $ ansible nodes -i ansible-hosts -m ping }}} If you don’t see success everywhere then there is something wrong with your setup. Ask one of the tutorial leaders for help. === (b) The shell module === The '''shell''' module lets you run arbitrary SSH commands in parallel across a set of hosts. It’s useful for poking around, or if there is no Ansible module with the functionality you need. Try it out: {{{ $ ansible nodes -i ansible-hosts -m shell -a "hostname" }}} You can replace ''hostname'' above with any other Linux command. === (c) The setup module === The '''setup''' module gathers a bunch of information about each node and saves it in variables that you can reference in your Ansible playbooks. This will be really useful to do the tutorial! Try it out on a node to see what it collects (replace `` with your slicelet’s name): {{{ $ ansible .pcvm1-1.instageni.wisc.edu -i ansible-hosts -m setup }}} === (d) A simple playbook === Next, we will look at a simple Ansible playbook. An Ansible playbook is a YAML file containing a list of Ansible tasks. Copy the playbook below into a file called test.yaml: {{{ #!python --- - hosts: nodes remote_user: root tasks: - name: An example of a debug statement debug: var=ansible_hostname }}} Run the playbook as: {{{ $ ansible-playbook -i ansible-hosts test.yaml }}} The '''setup''' module is run automatically at the beginning of a playbook to populate variables for each node. The above playbook will dump the value of each node’s ''ansible_hostname'' variable. To run the playbook on a single node, replace ''nodes'' with the name of one of your slice nodes (e.g., slice338.pcvm3-7.instageni.nps.edu). ---- == 5. Create and run an Ansible playbook to install the software you'll need == Now you should have enough knowledge about Ansible to write a playbook to install the software you'll need on all the nodes. Below is a skeleton Ansible file that you use ([attachment:software-install.yaml download]). You will need to fill in the bits marked `# INSERT ARGUMENTS HERE` based on the instructions in the following section. If you get stuck at any point, you can take a look at this [attachment:software-install-solution.yaml solution]. {{{ #!python --- - hosts: nodes remote_user: root tasks: - name: Update apt cache apt: # INSERT ARGUMENTS HERE - name: Install dnsutils (for dig) apt: # INSERT ARGUMENTS HERE - name: Install geoip-bin (for geoiplookup) apt: # INSERT ARGUMENTS HERE }}} Run this playbook on your Ansible control machine against all the nodes in your slice. ---- = [wiki:GENIExperimenter/Tutorials/GENIExperimentEngine/Execute Next: Run Experiment] =