Fix the Ubuntu Fluentd image

For ubuntu, we actually use fluentd 0.14.22 and ruby 2.1.10 now.
Thus, we should use the specific gem version for the plugins:

 - fluent-plugin-rewrite-tag-filter:2.0.0
According to the README.md of this plugin[1]
It shows:
----------------------------------------------------------
| fluent-plugin-rewrite-tag-filter | Fluentd    | Ruby   |
|----------------------------------|------------|--------|
| >= 2.0.0                         | >= v0.14.2 | >= 2.1 |
| < 2.0.0                          | >= v0.12.0 | >= 1.9 |
----------------------------------------------------------

 - fluent-plugin-grok-parser:2.1.4
When using the fluent-plugin-rewrite-tag-filter 2.0.0 to fix this bug, another
bug[1] which is the same as this one[2] was triggered.
According to https://github.com/fluent/fluent-plugin-grok-parser, it shows:
---------------------------------------------------
| fluent-plugin-grok-parser | fluentd    | Ruby   |
|---------------------------|------------|--------|
| >= 1.0.0                  | >= v0.14.0 | >= 2.1 |
| < 1.0.0                   | >= v0.12.0 | >= 1.9 |
---------------------------------------------------

We actually use fluentd 0.14.22 now, but the version of fluent-plugin-grok-parser
is still pinned in 0.3.1. So we need to upgrade the fluent-plugin-grok-parser to
2.1.4.

[1] https://github.com/fluent/fluent-plugin-rewrite-tag-filter
[2] http://paste.openstack.org/show/626145/
[3] fluent/fluent-plugin-grok-parser#32

backport: pike

Change-Id: I47985113fe732569d640a262ca832c6edc8c2bb6
Partial-Bug: #1730664

docker/fluentd/Dockerfile.j2

@@ -47,11 +47,9 @@ RUN ulimit -n 65536 \
     && chown -R fluentd: /etc/fluentd /var/run/fluentd
 
 {% elif base_distro in ['debian', 'ubuntu'] %}
-# NOTE: We use fluentd version is v12.0 so fluent-plugin-grok-parse version should < 1.0.0.
-# https://github.com/fluent/fluent-plugin-grok-parser
 RUN ulimit -n 65536 \
     && sed -i -e "s/USER=td-agent/USER=root/" -e "s/GROUP=td-agent/GROUP=root/" /etc/init.d/td-agent \
-    && td-agent-gem install fluent-plugin-parser fluent-plugin-kubernetes_metadata_filter fluent-plugin-elasticsearch fluent-plugin-grep fluent-plugin-grok-parser:0.3.1 fluent-plugin-rewrite-tag-filter fluent-plugin-secure-forward \
+    && td-agent-gem install fluent-plugin-parser fluent-plugin-kubernetes_metadata_filter fluent-plugin-elasticsearch fluent-plugin-grep fluent-plugin-grok-parser:2.1.4 fluent-plugin-rewrite-tag-filter:2.0.0 fluent-plugin-secure-forward \
     && rm -f /etc/td-agent/td-agent.conf
 
 COPY fluentd_sudoers /etc/sudoers.d/kolla_fluentd_sudoers