[ansible-project] Dictionary elements access within group_vars

[Daniel Siechniewicz]

Hi,

I'm using ansible[-playbook] 1.9.0.1.

I have 4 "proxy" hosts talking to 2 "app" hosts:

proxy1 -> app1
proxy2 -> app1
proxy3 -> app2
proxy4 -> app2

In group vars I defined:

proxy_to_app_map:
1: 1
2: 1
3: 2
4: 2

proxy_no: "{{ ansible_hostname | regex_replace('^.*([0-9]+)$', '\\\\1') }}"
app_no: "{{ proxy_to_app_map[proxy_no] }}"


I'm getting:

ok: [proxy1] => {
"var": {
"proxy_no": "1"
}
}

and so on, but then I get a string instead of a specific dictionary value
(I expect a number, 1 or 2).

ok: [proxy1] => {

"var": {

"app_no": "{{ proxy_to_app_map[proxy_no] }}"

}

}

I tried this:
app_no: "{{ proxy_to_app_map.proxy_no }}"

And this
app_no: proxy_to_app_map.proxy_no

And this
app_no: "proxy_to_app_map.proxy_no"

and it still does not access the value. Why does this (not) happen? Is
there any documentation somewhere that would describe the rules of what
gets interpolated and what doesn't?

I have something like that later on, but it won't work without proper
app_no.

app_peer_host: "{{ ansible_hostname | regex_replace('^proxy', 'app') |
regex_replace(proxy_no + '$', app_no) }}"
app_peer_ip: "{{ hostvars[app_peer_host]['ansible_eth0']['ipv4']['address']
}}"

I'm using the hostvars trick like in the app_peer_ip in many places so some
interpolation works within group vars, but not all. Is this because
hostvars is a dict defined "externally" and proxy_to_app_map internally?

A workaround is something like that:

proxy_to_app_map:
proxy1: app1
proxy2: app1
proxy3: app2
proxy4: app2

app_peer_host: "{{ proxy_to_app_map[ansible_hostname] }}"

Which does work, and looks simpler, but would need to be defined for every
environment separately (real hostnames are more complex than proxy and
app), and that's lots of defining.

This leads me to a conclusion that a variable defined within group_vars
cannot be used as a key "identifier" to access a dictionary element if that
dictionary is also defined in group_vars. Is that the case?


Regards,
Daniel

[Daniel Siechniewicz]

Replying to myself.

Well, it was just integer vs. string in the end. So yeah, PEBKAC. Quoting
everything in proxy_to_app_map did the trick.


Regards,
Daniel

Post by Daniel Siechniewicz
Hi,
I'm using ansible[-playbook] 1.9.0.1.
proxy1 -> app1
proxy2 -> app1
proxy3 -> app2
proxy4 -> app2
1: 1
2: 1
3: 2
4: 2
proxy_no: "{{ ansible_hostname | regex_replace('^.*([0-9]+)$', '\\\\1') }}"
app_no: "{{ proxy_to_app_map[proxy_no] }}"
ok: [proxy1] => {
"var": {
"proxy_no": "1"
}
}
and so on, but then I get a string instead of a specific dictionary value
(I expect a number, 1 or 2).
ok: [proxy1] => {
"var": {
"app_no": "{{ proxy_to_app_map[proxy_no] }}"
}
}
app_no: "{{ proxy_to_app_map.proxy_no }}"
And this
app_no: proxy_to_app_map.proxy_no
And this
app_no: "proxy_to_app_map.proxy_no"
and it still does not access the value. Why does this (not) happen? Is
there any documentation somewhere that would describe the rules of what
gets interpolated and what doesn't?
I have something like that later on, but it won't work without proper
app_no.
app_peer_host: "{{ ansible_hostname | regex_replace('^proxy', 'app') |
regex_replace(proxy_no + '$', app_no) }}"
app_peer_ip: "{{
hostvars[app_peer_host]['ansible_eth0']['ipv4']['address'] }}"
I'm using the hostvars trick like in the app_peer_ip in many places so
some interpolation works within group vars, but not all. Is this because
hostvars is a dict defined "externally" and proxy_to_app_map internally?
proxy1: app1
proxy2: app1
proxy3: app2
proxy4: app2
app_peer_host: "{{ proxy_to_app_map[ansible_hostname] }}"
Which does work, and looks simpler, but would need to be defined for every
environment separately (real hostnames are more complex than proxy and
app), and that's lots of defining.
This leads me to a conclusion that a variable defined within group_vars
cannot be used as a key "identifier" to access a dictionary element if that
dictionary is also defined in group_vars. Is that the case?
Regards,
Daniel