feat(connectors): add generic JDBC source connector

Adds a JDBC source connector that polls a configured SQL query against any
JDBC-compliant database (PostgreSQL, MySQL, Oracle, SQL Server, H2) through an
embedded JVM and produces each row as a JSON message. Supports bulk and
incremental (offset-tracked) modes with persisted offset state.

Also adds the shared connector integration-test harness and a small TCP
listener change so that harness can read the server's written runtime config
when bound to a fixed port. The matching JDBC sink connector follows in a
separate PR.

Author: shbhmrzd

.config/nextest.toml

@@ -48,6 +48,18 @@ max-threads = 1
 filter = 'package(integration) and test(/connectors::elasticsearch::/)'
 test-group = "elasticsearch"
 
+# JDBC tests each start their own iggy-server plus a Postgres testcontainer and
+# an embedded JVM, and they share a JDBC driver JAR downloaded to a single path
+# on first run. nextest runs each test in its own process, so the in-source
+# `#[serial]` guard does not serialize them here; `max-threads = 1` does, which
+# avoids resource contention and a race to download the same driver JAR.
+[test-groups.jdbc]
+max-threads = 1
+
+[[profile.default.overrides]]
+filter = 'package(integration) and test(/connectors::jdbc::/)'
+test-group = "jdbc"
+
 [profile.default]
 slow-timeout = { period = "60s", terminate-after = 5 }
 

.github/workflows/_build_rust_artifacts.yml

@@ -46,7 +46,7 @@ on:
       connector_plugins:
         type: string
         required: false
-        default: "iggy_connector_elasticsearch_sink,iggy_connector_elasticsearch_source,iggy_connector_iceberg_sink,iggy_connector_postgres_sink,iggy_connector_postgres_source,iggy_connector_quickwit_sink,iggy_connector_random_source,iggy_connector_s3_sink,iggy_connector_stdout_sink"
+        default: "iggy_connector_elasticsearch_sink,iggy_connector_elasticsearch_source,iggy_connector_iceberg_sink,iggy_connector_jdbc_source,iggy_connector_postgres_sink,iggy_connector_postgres_source,iggy_connector_quickwit_sink,iggy_connector_random_source,iggy_connector_s3_sink,iggy_connector_stdout_sink"
         description: "Comma-separated list of connector plugin crates to build as shared libraries"
     outputs:
       artifact_name:

.github/workflows/edge-release.yml

@@ -104,6 +104,7 @@ jobs:
             - `iggy_connector_elasticsearch_sink`
             - `iggy_connector_elasticsearch_source`
             - `iggy_connector_iceberg_sink`
+            - `iggy_connector_jdbc_source`
             - `iggy_connector_postgres_sink`
             - `iggy_connector_postgres_source`
             - `iggy_connector_quickwit_sink`

Cargo.lock

@@ -46,6 +46,7 @@ members = [
     "core/connectors/sinks/stdout_sink",
     "core/connectors/sources/elasticsearch_source",
     "core/connectors/sources/influxdb_source",
+    "core/connectors/sources/jdbc_source",
     "core/connectors/sources/postgres_source",
     "core/connectors/sources/random_source",
     "core/consensus",

Cargo.toml

@@ -97,6 +97,7 @@ Please refer to the **[Source documentation](https://github.com/apache/iggy/tree
 ### Available Sources
 
 - **Elasticsearch Source** - polls documents from Elasticsearch indices
+- **JDBC Source** - reads rows from any JDBC-compliant database (PostgreSQL, MySQL, Oracle, SQL Server, H2) via an embedded JVM; bulk and incremental modes
 - **PostgreSQL Source** - reads rows from PostgreSQL tables with multiple consumption strategies (delete after read, mark as processed, timestamp tracking)
 - **Random Source** - generates random test messages (useful for testing/development)
 

core/connectors/README.md

@@ -0,0 +1,81 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+# Example JDBC Source Connector Configuration - BULK MODE
+# Bulk mode works with ALL JDBC databases without any special requirements
+# No tracking column needed - just executes your query and fetches results
+
+type = "source"
+key = "jdbc_bulk_example"
+enabled = true
+version = 0
+name = "JDBC Bulk Mode Source"
+path = "target/release/libiggy_connector_jdbc_source"
+plugin_config_format = "toml"
+
+[plugin_config]
+# This example uses PostgreSQL, but bulk mode works identically with:
+# MySQL, Oracle, SQL Server, H2, Derby, DB2, etc.
+jdbc_url = "jdbc:postgresql://localhost:5432/warehouse"
+
+# Database credentials can be in URL or separate
+# jdbc_url = "jdbc:postgresql://localhost:5432/warehouse?user=myuser&password=mypass"
+username = "warehouse_user"
+password = "secret"
+
+driver_class = "org.postgresql.Driver"
+driver_jar_path = "/opt/jdbc-drivers/postgresql-42.6.0.jar"
+
+# Bulk mode: Any valid SELECT query
+# Can include JOINs, aggregations, complex WHERE clauses, etc.
+query = """
+SELECT
+    p.product_id,\
+    p.product_name,
+    p.category,
+    p.price,
+    COUNT(o.order_id) as total_orders,
+    SUM(o.quantity) as total_quantity
+FROM products p
+LEFT JOIN orders o ON p.product_id = o.product_id
+GROUP BY p.product_id, p.product_name, p.category, p.price
+"""
+
+# Poll once per hour for daily snapshots
+poll_interval = "1h"
+
+# Large batch size for full table scans
+batch_size = 10000
+
+# BULK MODE - no tracking column needed!
+mode = "bulk"
+
+# Bulk mode benefits:
+# - No tracking column required
+# - Works with any SELECT query
+# - Supports complex queries (JOINs, aggregations, window functions)
+# - Perfect for periodic snapshots
+# - Universal compatibility with all databases
+
+snake_case_columns = true
+include_metadata = false
+
+[[streams]]
+stream = "warehouse"
+topic = "product_summary"
+partition_id = 1
+schema = "json"

core/connectors/runtime/example_config/connectors/jdbc_bulk_mode.toml

@@ -0,0 +1,60 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+# Example JDBC Source Connector Configuration for H2 Database
+# H2 is useful for testing and development as it's an embedded Java database
+
+type = "source"
+key = "jdbc_h2_example"
+enabled = true
+version = 0
+name = "JDBC H2 Source"
+path = "target/release/libiggy_connector_jdbc_source"
+plugin_config_format = "toml"
+
+[plugin_config]
+# H2 connection URL (in-memory database)
+jdbc_url = "jdbc:h2:mem:testdb;DB_CLOSE_DELAY=-1"
+
+# H2 JDBC driver
+driver_class = "org.h2.Driver"
+
+# Path to H2 driver JAR
+# Download from: https://repo1.maven.org/maven2/com/h2database/h2/2.2.224/h2-2.2.224.jar
+# Note: Update this path to match where you downloaded the JAR file
+driver_jar_path = "/tmp/jdbc-drivers/h2-2.2.224.jar"
+
+# H2 credentials (default)
+username = "sa"
+password = ""
+
+# Simple query for testing
+query = "SELECT * FROM users WHERE id > {last_offset} ORDER BY id"
+
+poll_interval = "10s"
+batch_size = 100
+tracking_column = "id"
+initial_offset = "0"
+mode = "incremental"
+snake_case_columns = false
+include_metadata = true
+
+[[streams]]
+stream = "test"
+topic = "users"
+partition_id = 1
+schema = "json"

core/connectors/runtime/example_config/connectors/jdbc_h2.toml

@@ -0,0 +1,85 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+# Example JDBC Source Connector Configuration for MySQL
+# This file demonstrates how to configure the JDBC source connector
+# to read data from a MySQL database and publish to Iggy streams.
+
+type = "source"
+key = "jdbc_mysql_example"
+enabled = true
+version = 0
+name = "JDBC MySQL Source"
+path = "target/release/libiggy_connector_jdbc_source"
+plugin_config_format = "toml"
+
+[plugin_config]
+# JDBC connection URL
+# Option 1: Separate credentials (recommended)
+jdbc_url = "jdbc:mysql://localhost:3306/ecommerce?useSSL=false&serverTimezone=UTC"
+
+# Option 2: Embedded credentials in URL (alternative)
+# jdbc_url = "jdbc:mysql://iggy_user:iggy_password@localhost:3306/ecommerce?useSSL=false&serverTimezone=UTC"
+
+# JDBC driver class name
+driver_class = "com.mysql.cj.jdbc.Driver"
+
+# Path to JDBC driver JAR file
+# Download from: https://repo1.maven.org/maven2/com/mysql/mysql-connector-j/8.0.33/mysql-connector-j-8.0.33.jar
+driver_jar_path = "/opt/jdbc-drivers/mysql-connector-j-8.0.33.jar"
+
+# Database credentials (optional if included in jdbc_url)
+username = "iggy_user"
+password = "iggy_password"
+
+# SQL query to execute
+# Use {last_offset} placeholder for incremental reads
+query = "SELECT * FROM orders WHERE updated_at > {last_offset} ORDER BY updated_at ASC"
+
+# How often to poll the database
+poll_interval = "30s"
+
+# Maximum number of rows to fetch per poll
+batch_size = 1000
+
+# Column to track for incremental reads (must be in query result)
+tracking_column = "updated_at"
+
+# Initial offset value for the first poll
+initial_offset = "2024-01-01 00:00:00"
+
+# Source mode: "incremental" or "bulk"
+# Note: Both modes work with ALL JDBC databases (MySQL, Oracle, PostgreSQL, etc.)
+# - incremental: Tracks last offset, avoids duplicate reads
+# - bulk: Full table scan, no offset tracking
+mode = "incremental"
+
+# Convert column names to snake_case (e.g., OrderDate -> order_date)
+snake_case_columns = true
+
+# Include metadata wrapper in output messages
+include_metadata = true
+
+# Custom JVM options (optional)
+jvm_options = ["-Xmx512m", "-Xms128m"]
+
+# Target Iggy stream and topic
+[[streams]]
+stream = "ecommerce"
+topic = "orders"
+partition_id = 1
+schema = "json"