[ansible-project] Using results of RDS facts to update a template

[Dave Thomas]

I’d trying to get the database endpoint into a Rails database.ml file. I
know the RDS id, so I can get the endpoint using reds/command: facts.

Unfortunately, the RDS play has to use localhost, while the template write
uses the actual target host.

So far I’ve done it using

- hosts: localhost
connection: local
gather_facts: False
vars_files:
- ../ec2/ec2_params.yml

tasks:
- rds:
command: facts
region: "{{ region }}"
instance_name: "{{ database_instance }}"
register: db_facts

- name: save remote host
copy:
content: "{{ db_facts.instance }}"
dest: /tmp/db_facts

- hosts: tag_class_apps
become: yes
become_user: "{{ app_user }}"
gather_facts: False

vars:
db_facts: "{{ lookup('file', '/tmp/db_facts')|from_json }}"

tasks:
- name: Update database.yml with current rds endpoint
template:
src: ../roles/app_directories/templates/config/database.yml # this template uses db_facts.endpoint
dest: "{{ shared_path }}/config/database.yml"I can’t help feeling I’m making this too complex. What should I be doing?

I can't help feeling I'm making this too complicated. What magic am I
missing?


Cheers


Dave
​

[Jon Hadfield]

Rather than register the facts and write to a file, you can use a custom
lookup to query the endpoint based on the instance name. Then you can put
the following in your template file:
{{ lookup('aws_rds_endpoint_port_from_instance_name', (region,
database_instance )) }}
where region is a variable containing the region you use and
database_instance is the name.

I've written some additional lookups, including one to get the endpoint of
an RDS instance based on name
here: https://github.com/jonhadfield/ansible-lookups
I'm also putting together a guide (nearly finished) that includes their use
here: http://lessknown.info.

[Jon Hadfield]

Oops, that should have read:
{{ lookup('aws_rds_endpoint_*name*_from_instance_name', (region,
database_instance )) }}
The other returns the port.

[Baraa Basata]

Hi Dave,

I use a single play to get an RDS endpoint and write database.yml. It uses
`local_action` to delegate the rds facts lookup to localhost.

For the example that you've shared, it would look like the following:

- hosts: tag_class_apps
become: yes
become_user: "{{ app_user }}"
gather_facts: False

tasks:
- local_action:
module: rds
command: facts
region: "{{ region }}"
instance_name: "{{ database_instance }}"
register: db_facts

- name: Update database.yml with current rds endpoint
template:
src: ../roles/app_directories/templates/config/database.yml


I hope this is helpful.

-Baraa

Post by Dave Thomas
I’d trying to get the database endpoint into a Rails database.ml file. I
know the RDS id, so I can get the endpoint using reds/command: facts.
Unfortunately, the RDS play has to use localhost, while the template write
uses the actual target host.
So far I’ve done it using
- hosts: localhost
connection: local
gather_facts: False
- ../ec2/ec2_params.yml
command: facts
region: "{{ region }}"
instance_name: "{{ database_instance }}"
register: db_facts
- name: save remote host
content: "{{ db_facts.instance }}"
dest: /tmp/db_facts
- hosts: tag_class_apps
become: yes
become_user: "{{ app_user }}"
gather_facts: False
db_facts: "{{ lookup('file', '/tmp/db_facts')|from_json }}"
- name: Update database.yml with current rds endpoint
src: ../roles/app_directories/templates/config/database.yml # this template uses db_facts.endpoint
dest: "{{ shared_path }}/config/database.yml"I can’t help feeling I’m making this too complex. What should I be doing?
I can't help feeling I'm making this too complicated. What magic am I
missing?
Cheers
Dave
​

[Dave Thomas]

Post by Baraa Basata
Hi Dave,
I use a single play to get an RDS endpoint and write database.yml. It uses
`local_action` to delegate the rds facts lookup to localhost.

Of course. Thank you!


Dave

Post by Baraa Basata
​