Hi Masahiro,
Ok so I've collected the data, here it is...
1. sudo /usr/sbin/td-agent-gem list
actionmailer (4.1.9)
actionpack (4.1.9)
actionview (4.1.9)
activemodel (4.1.9)
activerecord (4.1.9)
activesupport (4.1.9)
addressable (2.3.6)
arel (5.0.1.20140414130214)
aws-sdk (1.60.1)
aws-sdk-v1 (1.60.1)
bigdecimal (1.2.4)
bson (1.10.2)
bson_ext (1.10.2)
builder (3.2.2)
bundler (1.7.4)
celluloid (0.15.2)
cool.io (1.2.4)
diff-lcs (1.2.5)
draper (1.4.0)
erubis (2.7.0)
fluent-logger (0.4.10)
fluent-mixin-config-placeholders (0.3.0)
fluent-mixin-plaintextformatter (0.2.6)
fluent-plugin-geoip (0.4.0)fluent-plugin-mongo (0.7.5)
fluent-plugin-rewrite-tag-filter (1.4.1)
fluent-plugin-s3 (0.5.3)
fluent-plugin-scribe (0.10.14)
fluent-plugin-td (0.10.25)
fluent-plugin-td-monitoring (0.2.0)
fluent-plugin-webhdfs (0.4.1)
fluentd (0.10.60)
fluentd-ui (0.3.14)
font-awesome-rails (4.2.0.0)
haml (4.0.6)
haml-rails (0.5.3)
hike (1.2.3)
hirb (0.7.3)
http_parser.rb (0.6.0)
httpclient (2.4.0)
i18n (0.6.11)
io-console (0.4.2)
ipaddress (0.8.0)
jbuilder (2.2.6)
jquery-rails (3.1.2)
json (1.8.1)
kramdown (1.5.0)
kramdown-haml (0.0.3)
ltsv (0.1.0)
mail (2.6.3)
mime-types (2.4.3)
mini_portile (0.6.0)
minitest (5.4.2, 4.7.5)
mixlib-cli (1.5.0)
mixlib-config (2.1.0)
mixlib-log (1.6.0)
mixlib-shellout (2.0.1)
mongo (1.10.2)
msgpack (0.5.11)
multi_json (1.10.1)
nokogiri (1.6.3.1)
ohai (6.20.0)
parallel (0.6.5)
psych (2.0.5)
puma (2.11.0)
rack (1.5.2)
rack-test (0.6.2)
rails (4.1.9)
railties (4.1.9)
rake (10.1.0)
rdoc (4.1.0)
request_store (1.1.0)
rubyzip (1.1.6, 0.9.9)
sass (3.2.19)
sass-rails (4.0.4)
settingslogic (2.0.9)
sigdump (0.2.2)
sprockets (2.11.3)
sprockets-rails (2.2.0)
string-scrub (0.0.5)
sucker_punch (1.0.5)
systemu (2.5.2)
td (0.11.6)
td-client (0.8.67)
td-logger (0.3.24)
test-unit (2.1.3.0)
thor (0.19.1)
thread_safe (0.3.4)
thrift (0.8.0)
tilt (1.4.1)
timers (1.1.0)
tzinfo (1.2.2)
tzinfo-data (1.2015.1)
uuidtools (2.1.5)
webhdfs (0.6.0)
yajl-ruby (1.2.1)
2. cat /var/log/td-agent/td-agent.log
2015-04-23 08:52:55 +0100 [info]: reading config file path="/etc/td-agent/td-agent.conf"
2015-04-23 08:52:55 +0100 [info]: starting fluentd-0.10.60
2015-04-23 08:52:55 +0100 [info]: gem 'fluent-mixin-config-placeholders' version '0.3.0'
2015-04-23 08:52:55 +0100 [info]: gem 'fluent-mixin-plaintextformatter' version '0.2.6'
2015-04-23 08:52:55 +0100 [info]: gem 'fluent-plugin-geoip' version '0.4.0'
2015-04-23 08:52:55 +0100 [info]: gem 'fluent-plugin-mongo' version '0.7.5'
2015-04-23 08:52:55 +0100 [info]: gem 'fluent-plugin-rewrite-tag-filter' version '1.4.1'
2015-04-23 08:52:55 +0100 [info]: gem 'fluent-plugin-s3' version '0.5.3'
2015-04-23 08:52:55 +0100 [info]: gem 'fluent-plugin-scribe' version '0.10.14'
2015-04-23 08:52:55 +0100 [info]: gem 'fluent-plugin-td' version '0.10.25'
2015-04-23 08:52:55 +0100 [info]: gem 'fluent-plugin-td-monitoring' version '0.2.0'
2015-04-23 08:52:55 +0100 [info]: gem 'fluent-plugin-webhdfs' version '0.4.1'
2015-04-23 08:52:55 +0100 [info]: gem 'fluentd' version '0.10.60'
2015-04-23 08:52:55 +0100 [info]: using configuration file: <ROOT>
<source>
type tail
read_from_head true
path /mnt/juniperextended.txt
pos_file /mnt/junipergeo.pos
tag geoip.
format /^.*?"Juniper: id=(?<id>\S*) time=\\"(?<time>.*?)\\" pri=(?<priority>\S*) fw=(?<firewall>\S*) vpn=(?<nodename>\S*) user=(?<user>\S*) realm=\\"(?<realm>[^\\]*)\\" roles=\\"(?<roles>[^\\]*)\\" proto=(?<proto>.*?) src=(?<sourceip>\S*) dst=(?<destip>\S*) dstname=(?<dstname>\S*) type=(?<type>\S*) op=(?<op>\S*) arg=\\"(?<arg>.*?)\\" result=(?<result>\S*) sent=(?<bytes_sent>\S*) rcvd=(?<bytes_received>\S*) agent=\\"(?<agent>.*?)\\" duration=(?<duration>\S*) msg=\\"(?<eventcode>.*?):(?<eventmessage>.*?)""}/
</source>
<match geoip.**>
type geoip
geoip_lookup_key sourceip
enable_key_country_code geoip_country
enable_key_city geoip_city
enable_key_latitude geoip_lat
enable_key_longitude geoip_lon
flush_interval 10s
remove_tag_prefix geoip.
add_tag_prefix squeeze.
buffer_type file
buffer_queue_limit 1000000
buffer_path /mnt/buffer/geo/squeeze-isogeo.*.buffer
buffer_chunk_limit 50m
</match>
<match squeeze.**>
type file
path /mnt/junipergeoout.txt
append true
</match>
</ROOT>
2015-04-23 08:52:55 +0100 [info]: adding source type="tail"
2015-04-23 08:52:55 +0100 [info]: adding match pattern="geoip.**" type="geoip"
2015-04-23 08:52:55 +0100 [error]: config error file="/etc/td-agent/td-agent.conf" error="Unknown output plugin 'geoip'. Run 'gem search -rd fluent-plugin' to find plugins"
2015-04-23 08:52:55 +0100 [info]: process finished code=256
2015-04-23 08:52:55 +0100 [warn]: process died within 1 second. exit.
cat /etc/td-agent/td-agent.conf
<source>
type tail
read_from_head true
path /mnt/juniperextended.txt
pos_file /mnt/junipergeo.pos
tag geoip.
format /^.*?"Juniper: id=(?<id>\S*) time=\\"(?<time>.*?)\\" pri=(?<priority>\S*) fw=(?<firewall>\S*) vpn=(?<nodename>\S*) user=(?<user>\S*) realm=\\"(?<realm>[^\\]*)\\" roles=\\"(?<roles>[^\\]*)\\" proto=(?<proto>.*?) src=(?<sourceip>\S*) dst=(?<destip>\S*) dstname=(?<dstname>\S*) type=(?<type>\S*) op=(?<op>\S*) arg=\\"(?<arg>.*?)\\" result=(?<result>\S*) sent=(?<bytes_sent>\S*) rcvd=(?<bytes_received>\S*) agent=\\"(?<agent>.*?)\\" duration=(?<duration>\S*) msg=\\"(?<eventcode>.*?):(?<eventmessage>.*?)""}/
</source>
<match geoip.**>
type geoip
geoip_lookup_key sourceip
enable_key_country_code geoip_country
enable_key_city geoip_city
enable_key_latitude geoip_lat
enable_key_longitude geoip_lon
flush_interval 10s
remove_tag_prefix geoip.
add_tag_prefix squeeze.
buffer_type file
buffer_queue_limit 1000000
buffer_path /mnt/buffer/geo/squeeze-isogeo.*.buffer
buffer_chunk_limit 50m
</match>
<match squeeze.**>
type file
path /mnt/junipergeoout.txt
append true
</match>