Flow Batch SQL Source Connector

This is a connector which periodically executes SQL SELECT queries and emits the resulting rows into Flow as JSON documents. It is designed to be a flexible but not particularly point-and-click friendly tool, however if extended with suitable discovery logic it could become much more usable.

Useful commands:

$ docker build -t ghcr.io/estuary/source-mysql-batch:local -f source-mysql-batch/Dockerfile .
$ docker exec -it source-mysql-db-1 mysql test --user=root --port=3306 --host=127.0.0.1 --protocol=tcp --password=secret1234
$ flowctl raw discover --source acmeCo/flow.yaml
$ flowctl raw capture acmeCo/flow.yaml

Example flow.yaml for discovery:

---
captures:
  acmeCo/source-mysql-batch:
    endpoint:
      connector:
        image: "ghcr.io/estuary/source-mysql-batch:local"
        config:
          address: "127.0.0.1:3306"
          password: secret1234
          user: root
    bindings: []

And a fleshed-out catalog:

captures:
  acmeCo/something/source-mysql-batch:
    endpoint:
      connector:
        image: "ghcr.io/estuary/source-mysql-batch:local"
        config:
          address: "localhost:3306"
          password: "secret1234"
          user: "flow_capture"
    bindings:
      - resource:
          name: "foobar"
          template: >
            {{if .IsFirstQuery}}
              SELECT xmin, * FROM public.foobar;
            {{else}}
              SELECT xmin, * FROM public.foobar
                WHERE xmin::text::bigint > $1
                ORDER BY xmin::text::bigint;
            {{end}}
          cursor: ["xmin"]
          poll: 5s
        target: "acmeCo/something/foobar"

collections:
  acmeCo/something/foobar:
    key: [/xmin]
    schema:
      properties:
        xmin: {type: integer}
      required: [xmin]
      type: object