| | 48 | First create a starter Ansible playbook. Recall that a playbook is a YAML file containing a list of Ansible commands. Copy the following into a file called lab.yaml: |
| | 49 | |
| | 50 | {{{ |
| | 51 | --- |
| | 52 | - hosts: nodes |
| | 53 | remote_user: root |
| | 54 | tasks: |
| | 55 | - debug: var=ansible_hostname |
| | 56 | }}} |
| | 57 | |
| | 58 | Run the playbook as: |
| | 59 | |
| | 60 | {{{ |
| | 61 | $ ansible-playbook -i ansible-hosts --private-key id_rsa lab.yaml |
| | 62 | }}} |
| | 63 | |
| | 64 | 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). |
| | 65 | |
| | 66 | '''Pro Tip:''' Solve the problem on one node in your slice first, then deploy your solution to the remaining nodes. One thing at a time |
| | 67 | |
| | 68 | Now, think about how you are going to solve the problems of this tutorial. Recall that your goal is to fetch a parameterized URL on each node of your slicelet: |
| | 69 | |
| | 70 | ''!http://www.lively-web.org/nodejs/GEETutorial/helloWorld?slice=<slice name>&name=<container name>&ip=<IP of host>&local=<IP of container>&lat=<latitude of host>&lng=<longitude of container>'' |
| | 71 | |
| | 72 | For instance, the IP address visible inside the slicelet (as reported in the variable ''ansible_eth0.ipv4.address'') is a private address -- it is not the control address of the host, which is one piece of information you want. There are a number of ways that you could discover the control address, including running '''dig +short''' on the host’s name (see if you can find a variable that contains this; HINT: you need it to SSH into the slicelet) or by running '''curl''' against a webserver that reports the client’s externally visible address. |
| | 73 | |
| | 74 | Another requirement of the lab is to map the control IP address obtained above to the latitude and longitude for each node. For instance you can use the '''geoiplookup''' tool, provided by package '''geoip-bin'''. |
| | 75 | |
| | 76 | {{{ |
| | 77 | $ geoiplookup -f <data file> <ip address> |
| | 78 | }}} |
| | 79 | |
| | 80 | where ''<data file>'' is the database of IP addresses and locations. You can find a good one at: http://geolite.maxmind.com/download/geoip/database/GeoLiteCity.dat.gz, which you’ll have to download to each node and unzip. |
| | 81 | A different approach would be to run '''curl''' against a webserver that maps IP address to latitude and longitude, such as http://ipinfo.io, and parse the output. '''NOTE:''' this particular website rate-limits the number of requests per node per day, so if you use it, make only a single request per node and save the result in a file… keep in mind that everyone in the tutorial may be hitting this server from the same set of hosts! |
| | 82 | |
