Ansible install RethinkDB on ubuntu 16 - package

Question

I am trying to use ansible package to install a specific version of RethinkDB on ubuntu 16.04.
I use :
- name: Ensure rethinkDB package repository is present
apt_repository: repo='deb http://download.rethinkdb.com/apt xenial main' state=present
tags:
- rethinkdb
- name: install RethinkDB
package: name=rethinkdb-2.3.2 state=latest
tags:
- rethinkdb
However I get the following error:
TASK [install RethinkDB]
******************************************************* task path: /Users/nha/.../playbook.yml:173 fatal:
[machine]: FAILED! => {"changed": false, "failed": true, "msg": "No
package matching 'rethinkdb-2.3.2' is available"} to retry, use:
--limit #ops/ansible/playbook.retry
Even leaving out the version, I get the error:
TASK [install RethinkDB]
******************************************************* task path: /Users/nha/.../playbook.yml:173 fatal:
[machine]: FAILED! => {"cache_update_time": 0, "cache_updated": false,
"changed": false, "failed": true, "msg": "'/usr/bin/apt-get -y -o
\"Dpkg::Options::=--force-confdef\" -o
\"Dpkg::Options::=--force-confold\" install 'rethinkdb'' failed:
E: There were unauthenticated packages and -y was used without
--allow-unauthenticated\n", "stderr": "E: There were unauthenticated packages and -y was used without --allow-unauthenticated\n", "stdout":
"Reading package lists...\nBuilding dependency tree...\nReading state
information...\nThe following additional packages will be installed:\n
libcurl3\nThe following NEW packages will be installed:\n libcurl3
rethinkdb\n0 upgraded, 2 newly installed, 0 to remove and 0 not
upgraded.\nNeed to get 11.2 MB of archives.\nAfter this operation,
40.2 MB of additional disk space will be used.\nWARNING: The following packages cannot be authenticated!\n rethinkdb\n", "stdout_lines":
["Reading package lists...", "Building dependency tree...", "Reading
state information...", "The following additional packages will be
installed:", " libcurl3", "The following NEW packages will be
installed:", " libcurl3 rethinkdb", "0 upgraded, 2 newly installed, 0
to remove and 0 not upgraded.", "Need to get 11.2 MB of archives.",
"After this operation, 40.2 MB of additional disk space will be
used.", "WARNING: The following packages cannot be authenticated!", "
rethinkdb"]} to retry, use: --limit #ops/ansible/playbook.retry

Answer 1

The first error message states that the RethinkDB apt repo doesn't contain a package for a 2.3.2 version.
The second error is because you haven't yet added the apt key to trust this repo. RethinkDB's Ubuntu installation instructions also mentions that you will need to add their apt key.
You can easily do this with the apt_key module:
- name: add rethinkdb apt key
apt_key: url=https://download.rethinkdb.com/apt/pubkey.gpg
As an aside, it doesn't really make much sense to specify a version and then also specify latest on the state.