edx-west: parameterize machine names in playbooks

playbooks/edx-west/README.md

+# Stanford Ansible Configuration Files
+
+This directory has the live playbooks that we use here at Stanford to
+maintain our instance of OpenEdX at [class.stanford.edu][c].  We check
+it in to this public repo since we think that others might benefit from
+seeing how we are configured.
+
+  [c]: https://class.stanford.edu/
+
+That said, we haven't documented things in here well, so we have no
+expectation that others will be able to make enough sense of this to
+give us useful contributions back.  Generally a PR affecting files in
+here will be ignored / rejected.
+
+This README is a useful proximate place to keep commands.  But it is 
+a public repo so we shouldn't store anything confidential in here.
+
+Other install docs:
+
+- Giulio's install doc [here][1].
+
+  [1]: https://docs.google.com/document/d/1ZDx51Jxa-zffyeKvHmTp_tIskLW9D9NRg9NytPTbnrA/edit#heading=h.iggugvghbcpf
+
+
+## Ansible Commands - Prod
+
+Generally we do installs as the "ubuntu" user.  You want to make
+sure that the stanford-deploy-20130415 ssh key is in your ssh agent.
+
+    ANSIBLE_CONFIG=prod-ansible.cfg ANSIBLE_EC2_INI=prod-ec2.ini ansible-playbook prod-app.yml -e "machine=app4" -u ubuntu -c ssh -i ./ec2.py
+
+Some specifics:
+
+* To hit multiple machines the -e parameter would look like this: ```"machine=app(1|2|4)"```.
+
+* Usually I do with the ```--list-hosts``` option first to verify that I'm
+  doing something sane before actually running.
+
+* To do the utility machines, use ```prod-worker.yml```.  Those also
+  take the machine variable.
+
+
+## Ansible Commands - Stage
+
+Command is:
+
+    ANSIBLE_CONFIG=stage-ansible.cfg ANSIBLE_EC2_INI=stage-ec2.ini ansible-playbook stage-app.yml -e "machine=app1" -u ubuntu -c ssh -i ./ec2.py
+
+

playbooks/edx-west/prod-app.yml

-# this gets all running prod webservers
+# This uses variable expansion so you can select machine(s) from the command line
+# using the -e flag.  See README for instructions on how to use.
+- hosts: ~tag_Name_{{machine}}_prod
+#
+# This alternative hits all running prod webservers.  Left here as an example.
 #- hosts: tag_environment_prod:&tag_function_webserver
-# or we can get subsets of them by name
-#- hosts: ~tag_Name_app1_prod
-#- hosts: ~tag_Name_app2_prod
-## this is the test box
-- hosts: ~tag_Name_app4_prod
-#- hosts: ~tag_Name_app(4|1|2)_prod
-## you can also do security group, but don't do that
-#- hosts: security_group_edx-prod-EdxappServerSecurityGroup-NSKCQTMZIPQB
   sudo: True
   vars_prompt:
     - name: "migrate_db"

playbooks/edx-west/prod-worker.yml

 - name: Basic util setup on all hosts
-# For all util machines
+# This uses variable expansion so you can select machine(s) from the command line
+# using the -e flag.  See README for instructions on how to use.
+  hosts: ~tag_Name_{{machine}}_prod
+#
+# This alternative hits all running prod webservers.  Left here as an example.
 #  hosts: tag_environment_prod:&tag_function_util
-# or we can get subsets of them by name
-  hosts: ~tag_Name_util(1|2)_prod
   sudo: True
   gather_facts: True
   vars:

playbooks/edx-west/stage-app.yml

+# This uses variable expansion so you can select machine(s) from the command line
+# using the -e flag.  See README for instructions on how to use.
+- hosts: ~tag_Name_{{machine}}_stage
+#
+# This alternative hits all running prod webservers.  Left here as an example.
 #- hosts: tag_environment_stage:&tag_function_webserver
-#- hosts: ~tag_Name_app10_stage
-- hosts: ~tag_Name_app1_stage
   sudo: True
   vars_prompt:
     - name: "migrate_db"

playbooks/edx-west/stage-worker.yml

 ---
 - name: Basic util setup on all hosts
-#- hosts: tag_environment_stage:&tag_function_util
-  hosts: ~tag_Name_util1_stage
+# This uses variable expansion so you can select machine(s) from the command line
+# using the -e flag.  See README for instructions on how to use.
+  hosts: ~tag_Name_{{machine}}_stage
+#
+# This alternative hits all running prod webservers.  Left here as an example.
+#  hosts: tag_environment_stage:&tag_function_util
   sudo: True
   gather_facts: True
   vars: