Kafka connect SMT to expand JSON string

This java lib implements Kafka connect SMT (Single Message Transformation) to extract JSON object from input string field.

Config

Use it in connector config file like this:

...
"transforms": "expand",
"transforms.expand.type": "com.redhat.insights.expandjsonsmt.ExpandJSON$Value",
"transforms.expand.sourceFields": "metadata"
...

Use dot notation for deeper fields (e. g. level1.level2).

Install to Kafka Connect

After build copy file target/kafka-connect-smt-expandjsonsmt-0.0.5-assemble-all.jar to Kafka Connect container `` copying to its docker image or so.

It can be done adding this line to Dockerfile:

COPY ./target/kafka-connect-smt-expandjsonsmt-0.0.5-assemble-all.jar $KAFKA_CONNECT_PLUGINS_DIR

Or download current release:

RUN curl -fSL -o /tmp/plugin.tar.gz \
    https://github.com/RedHatInsights/expandjsonsmt/releases/download/0.0.5/kafka-connect-smt-expandjsonsmt-0.0.5.tar.gz && \
    tar -xzf /tmp/plugin.tar.gz -C $KAFKA_CONNECT_PLUGINS_DIR && \
    rm -f /tmp/plugin.tar.gz;

Example

# build jar file and store to target directory
mvn package

# start example containers (kafka, postgres, elasticsearch, ...)
docker-compose up --build

# when containers started run in separate terminal:
cd dev
./connect.sh # init postgres and elasticsearch connectors
./show_topics.sh # check created topic 'dbserver1.public.hosts' in kafka
./show_es.sh # check transformed documents imported from postgres to elasticsearch

# ... stop containers
docker-compose down

Build release file

• Remove target directory if it exists.
• Increment version in pom.xml (e.g. to 0.0.3).
• Run build script: ./scripts/build_release.sh 0.0.3.
• Take *.tar.gz file from target folder and publish it.