[ansible-project] Reset vars between plays on same host

[Nick Tkach]

Is there a way to somehow "reset" variables in-between plays? What I'm
trying to do is make a playbook that creates my standard tomcat instance
layout.

So given the setup below, as I understand it you'd have "app" files
group_vars where you could set whatever things specific to that app
instance like port. Then you'd have in the
roles/tomcat-7/defaults/main.yml some default values for everything with
the idea you'd set what you actually care about in the top level
group_vars/app1.yml and app2.yml such as port number for that specific
app. Then you use an inventory file for a given environment (such as
dev.hosts) to "hook" together a given app with a given group of host(s).
Then you call ansible-playbook passing in the inventory file you care about
right now (such as dev.hosts), the top level playbook (such as
tomcat7servers.yml), Then Ansible would iterate through the playbook (
tomcat7servers.yml in this case), taking the group_vars/myapp1 and run the
tomcat-7 role on the myapp1 group of hosts. Then the same for myapp2.

That much seems like it works, but the problem I get is that there doesn't
seem to be a way to say ok, this time around I don't want to do both myapp1
and myapp2. I want to limit to just myapp2. I've tried doing something
like

ansible-playbook -i dev.hosts tomcat7servers.yml --limit=myapp2

but it picks up both. Not only that but unless I re-define values from the
myapp1 "run" it keeps the values from myapp1 when it hits myapp2. This
usually suggests I'm not "getting" something about how Ansible models
things. What am I "missing" about this picture? I want to be able to run
something like I gave above there and have a tomcat 7 on appsvr1.internal
created that has totally default except for the values explicitly set in
group_vars/myapp1 and another tomcat 7 on that same box that has totally
default values except for what's explcitly set in group_vars/myapp2.

/usr/local/apache-tomcat-7.0.51 (where this is just a totally plain tar
xzf of a tarball off Apache's site extracted as root so it's *NOT* writable)

Then the tomcat instances (owned by app user such as tcadm):
/appl/app1/
then under that
/bin
/conf/
/webapps
and so on


/appl/appt2/
same setup as app1 here, but different ports, different instance name


So, trying to extrapolate from Ansible best practices in the documentation
the local "repo" is something like this

roles/tomcat-7/defaults/main.yml (where you'd set things you don't normally
care about overriding like maxAjpThreads but you *could* override what's in
the group_vars top level)
roles/tomcat-7/tasks
roles/tomcat-7/templates
and so on

group_vars/ (where you'd have yml files with the values for a given
app-such as myapp1.yml, myapp2.yml)
(example myapp1.yml)
ajpPort: 8109
httpPort: 8180
instanceName: myapp1
(example myapp2.yml)
ajpPort: 8209
httpPort: 8280
instanceName: myapp2



dev.hosts (which would match up group_names (such as myapp1 and myapp2) to
actual hosts in dev environment)
(example dev.hosts)
[myapp1]
appsvr1.dev

[myapp2]
appsvr1.dev

tomcat7servers.yml ("matching" groups for the inventory to actual roles)
- hosts: myapp1
become_user: tomcat
roles:
- tomcat-7
tasks:
- include_vars: group_vars/myapp1.yml

- host: myapp2
become_user: tomcat
roles:
- tomcat-7
tasks:
- include_vars: group_vars/myapp2.yml