How to view a schema's JSON representation from the Confluent Schema Registry (Decoding encoded JSON with jq)

decoding-json-with-jq.adoc

Confluent Schema Registry supports REST to pull down schema definitions:

$ curl -s localhost:8081/subjects/asgard.demo.CUSTOMERS-raw-value/versions/latest

{"subject":"asgard.demo.CUSTOMERS-raw-value","version":1,"id":6,"schema":"{\"type\":\"record\",\"name\":\"Envelope\",\"namespace\":\"asgard.demo.CUSTOMERS\",\"fields\":[{\"name\":\"before\",\"type\":[\"null\",{\"type\":\"record\",\"name\":\"Value\",\"fields\":[{\"name\":\"id\",\"type\":\"int\"},{\"name\":\"first_name\",\"type\":[\"null\",\"string\"],\"default\":null},{\"name\":\"last_name\",\"type\":[\"null\",\"string\"],\"default\":null},{\"name\":\"email\",\"type\":[\"null\",\"string\"],\"default\":null},{\"name\":\"gender\",\"type\":[\"null\",\"string\"],\"default\":null},{\"name\":\"club_status\",\"type\":[\"null\",\"string\"],\"default\":null},{\"name\":\"comments\",\"type\":[\"null\",\"string\"],\"default\":null},{\"name\":\"create_ts\",\"type\":{\"type\":\"string\",\"connect.version\":1,\"connect.default\":\"1970-01-01T00:00:00Z\",\"connect.name\":\"io.debezium.time.ZonedTimestamp\"},\"default\":\"1970-01-01T00:00:00Z\"},{\"name\":\"update_ts\",\"type\":{\"type\":\"string\",\"connect.version\":1,\"connect.default\":\"1970-01-01T00:00:00Z\",\"connect.name\":\"io.debezium.time.ZonedTimestamp\"},\"default\":\"1970-01-01T00:00:00Z\"}],\"connect.name\":\"asgard.demo.CUSTOMERS.Value\"}],\"default\":null},{\"name\":\"after\",\"type\":[\"null\",\"Value\"],\"default\":null},{\"name\":\"source\",\"type\":{\"type\":\"record\",\"name\":\"Source\",\"namespace\":\"io.debezium.connector.mysql\",\"fields\":[{\"name\":\"version\",\"type\":[\"null\",\"string\"],\"default\":null},{\"name\":\"name\",\"type\":\"string\"},{\"name\":\"server_id\",\"type\":\"long\"},{\"name\":\"ts_sec\",\"type\":\"long\"},{\"name\":\"gtid\",\"type\":[\"null\",\"string\"],\"default\":null},{\"name\":\"file\",\"type\":\"string\"},{\"name\":\"pos\",\"type\":\"long\"},{\"name\":\"row\",\"type\":\"int\"},{\"name\":\"snapshot\",\"type\":[{\"type\":\"boolean\",\"connect.default\":false},\"null\"],\"default\":false},{\"name\":\"thread\",\"type\":[\"null\",\"long\"],\"default\":null},{\"name\":\"db\",\"type\":[\"null\",\"string\"],\"default\":null},{\"name\":\"table\",\"type\":[\"null\",\"string\"],\"default\":null},{\"name\":\"query\",\"type\":[\"null\",\"string\"],\"default\":null}],\"connect.name\":\"io.debezium.connector.mysql.Source\"}},{\"name\":\"op\",\"type\":\"string\"},{\"name\":\"ts_ms\",\"type\":[\"null\",\"long\"],\"default\":null}],\"connect.name\":\"asgard.demo.CUSTOMERS.Envelope\"}"}⏎

The schema element is encoded JSON. Wouldn’t it be nice to decode it and use jq to manipulate and pretty-print it?

• .schema extracts the schema element

• fromjson decodes it

$ curl -s localhost:8081/subjects/asgard.demo.CUSTOMERS-raw-value/versions/latest|jq '.schema|fromjson'

{
  "type": "record",
  "name": "Envelope",
  "namespace": "asgard.demo.CUSTOMERS",
  "fields": [
    {
      "name": "before",
      "type": [
        "null",
        {
          "type": "record",
          "name": "Value",
          "fields": [
            {
              "name": "id",
              "type": "int"
            },
            {
[…]