Could not load 'active_record/connection_adapters/mysql2_adapter'.

[CrazyZfp]

Dockerfile:

FROM fluent/fluentd:v1.4-1

# Use root account to use apk
USER root

# below RUN includes plugin as examples elasticsearch is not required
# you may customize including plugins as you wish
RUN apk add --no-cache --update --virtual .build-deps sudo build-base ruby-dev mysql-dev \
    && sudo gem install fluent-plugin-elasticsearch fluent-plugin-sql \
    && fluent-gem install mysql2 --no-document \
    && sudo gem sources --clear-all \
    && apk del .build-deps \
    && rm -rf /home/fluent/.gem/ruby/2.5.0/cache/*.gem

USER fluent

error:

Could not load 'active_record/connection_adapters/mysql2_adapter'. Make sure that the adapter in config/database.yml is valid. If you use an adapter other than 'mysql', 'mysql2', 'postgresql' or 'sqlite3' add the necessary adapter gem to the Gemfile.

mysql2 version is mysql2-0.5.2

[rolandjitsu]

I have a similar issue, but with the pg adapter.

EDIT Actually, my issue was that I removed libpq-dev (I am using a docker setup).

[repeatedly]

Sorry, I missed this issue.

&& sudo gem install fluent-plugin-elasticsearch fluent-plugin-sql
&& fluent-gem install mysql2 --no-document \

How about sudo gem install fluent-plugin-elasticsearch fluent-plugin-sql mysql2?

[rolandjitsu]

@repeatedly I'm getting a different error now:

 Specified 'postgresql' for database adapter, but the gem is not loaded. Add `gem 'pg'` to your Gemfile (and ensure its version is at the minimum required by ActiveRecord)

@repeatedly I've tried your suggestion as well, with the same result.

And my Dockerfile:

FROM fluent/fluentd:v1.4-debian-onbuild-1

USER root

RUN BUILD_DEPS="sudo make gcc g++ libc-dev ruby-dev" \
  && apt-get update \
  && apt-get install -y --no-install-recommends $BUILD_DEPS \
  && apt-get install -y libpq-dev \
  && sudo gem install fluent-plugin-sql pg --no-document \
  && sudo gem sources --clear-all \
  && SUDO_FORCE_REMOVE=yes \
    apt-get purge -y --auto-remove \
                  -o APT::AutoRemove::RecommendsImportant=false \
                  $BUILD_DEPS \
  && rm -rf /var/lib/apt/lists/* \
           /home/fluent/.gem/ruby/2.3.0/cache/*.gem

USER fluent

UPDATE: The following Dockerfile works for me now:

FROM fluent/fluentd:v1.4-debian-onbuild-1

USER root

RUN BUILD_DEPS="sudo make gcc g++ libc-dev ruby-dev" \
  && apt-get update \
  && apt-get install -y --no-install-recommends $BUILD_DEPS \
  && apt-get install -y libpq-dev \
  && sudo gem install fluent-plugin-sql pg \
  && fluent-gem install pg -v 0.21.0 --no-document \
  && sudo gem sources --clear-all \
  && SUDO_FORCE_REMOVE=yes \
    apt-get purge -y --auto-remove \
                  -o APT::AutoRemove::RecommendsImportant=false \
                  $BUILD_DEPS \
  && rm -rf /var/lib/apt/lists/* \
           /home/fluent/.gem/ruby/2.3.0/cache/*.gem

USER fluent

Note that you need the fluent.conf file and plugins folder to be at the same level as your dockerfile.