Oj is not installed, and failing back to Yajl for json parser even if oj gem is installed

[alexander-stepanov]

I can see this warning in the log when we have migrated from alpine 3.7 to 3.8 in our base Docker container with ruby 2.5.1, fluentd 1.2.5, and installed oj-3.6.10:

"#0 [http_input] Oj is not installed, and failing back to Yajl for json parser"

Steps to reproduce:
Run an official Alpine Docker container docker run -it --rm alpine:3.8 and execute the following commands:

apk add --update ruby ruby-dev ruby-irb build-base
gem install etc json oj webrick fluentd -N
fluentd -s
fluentd

An example log:

2018-09-22 08:21:33 +0000 [info]: starting fluentd-1.2.5 pid=1423 ruby="2.5.1"
2018-09-22 08:21:33 +0000 [info]: spawn command to main:  cmdline=["/usr/bin/ruby", "-Eascii-8bit:ascii-8bit", "/usr/bin/fluentd", "--under-supervisor"]
2018-09-22 08:21:33 +0000 [info]: gem 'fluentd' version '1.2.5'
2018-09-22 08:21:33 +0000 [info]: adding match pattern="debug.**" type="stdout"
2018-09-22 08:21:33 +0000 [info]: adding match pattern="system.**" type="forward"
2018-09-22 08:21:33 +0000 [info]: #0 adding forwarding server '192.168.0.12:24224' host="192.168.0.12" port=24224 weight=60 plugin_id="object:2aed9b79cc38"
2018-09-22 08:21:33 +0000 [info]: #0 [forward_output] adding forwarding server '192.168.0.11:24224' host="192.168.0.11" port=24224 weight=60 plugin_id="forward_output"
2018-09-22 08:21:33 +0000 [info]: adding source type="forward"
2018-09-22 08:21:33 +0000 [info]: adding source type="http"
2018-09-22 08:21:33 +0000 [info]: #0 [http_input] Oj is not installed, and failing back to Yajl for json parser
2018-09-22 08:21:33 +0000 [info]: adding source type="monitor_agent"
2018-09-22 08:21:33 +0000 [info]: adding source type="debug_agent"
2018-09-22 08:21:33 +0000 [info]: #0 starting fluentd worker pid=1427 ppid=1423 worker=0
2018-09-22 08:21:33 +0000 [info]: #0 delayed_commit_timeout is overwritten by ack_response_timeout
2018-09-22 08:21:33 +0000 [info]: #0 [forward_output] delayed_commit_timeout is overwritten by ack_response_timeout
2018-09-22 08:21:33 +0000 [info]: #0 [debug_agent_input] listening dRuby uri="druby://127.0.0.1:24230" object="Fluent::Engine" worker=0
2018-09-22 08:21:33 +0000 [info]: #0 [forward_input] listening port port=24224 bind="0.0.0.0"
2018-09-22 08:21:33 +0000 [info]: #0 fluentd worker is now running worker=0

The same scenario worked well in Alpine 3.7 (the only notable difference it had Ruby 2.4.4).

[okkez]

You must run gem install bigdecimal or apk add --update ruby-bigdecimal in you Dockerfile.
Because ruby-bigdecimal is the separated package.

[alexander-stepanov]

Thanks, @okkez
I've added the bigdecimal gem to our Dockerfile and it did the trick!