Senior AWS Engineer

Cynet Systems•Malvern, PA

About The Position

Our client is seeking a Senior AWS Engineer to extend an event-driven, serverless financial platform that combines Python-based AWS Glue ETL pipelines with Node.js Lambda microservices. The role develops and operates independently deployable services and multi-stage data pipelines for transaction files, with a focus on correctness, auditability, idempotency, security, testing, and operational observability. The engineer will maintain and extend AWS infrastructure, ETL workflows, and services; support CI/CD and multi-environment deployments; and produce technical documentation. The position also involves handling financial transaction and position data, including file validation, reconciliation, alerting, and persistence in Oracle and DynamoDB.

Requirements

Strong proficiency in Python 3.12 or later, including testable, well-structured ETL code.
Strong proficiency in current-LTS Node.js, including ES6+, async/await, and JavaScript or TypeScript for AWS Lambda microservices.
Experience designing and operating microservices architectures, including single-purpose services, loose coupling, independent deployment, event contracts, and idempotency.
Experience with AWS Glue, including PySpark, Glue 4.0, and DynamicFrames, and AWS Lambda Python and Node.js runtimes.
Experience using AWS Step Functions and Amazon States Language for workflow orchestration.
Experience with AWS SAM or CloudFormation infrastructure as code and multi-environment deployment.
Oracle SQL experience, including complex joins, DML across transactional schemas, and stored procedure-like code patterns.
DynamoDB experience with key design, GSIs, conditional writes, and pagination.
S3 event-driven architecture experience, including EventBridge notifications and data lake patterns such as Parquet.
Strong testing discipline using pytest/unittest and Jest/Mocha, mocking AWS services with moto and aws-sdk-client-mock, and stubbing Spark/Glue dependencies for offline unit tests.
Experience with financial or transactional data where correctness, auditability, and idempotency are critical.
CI/CD experience, ideally with Jenkins and multi-environment promotion gates.
Familiarity with CloudWatch metrics and logs, Grafana, and operational dashboards.

Nice To Haves

AWS SDK for Node.js version 3 is preferred.
CI/CD experience with Jenkins is ideal.

Responsibilities

Design, build, and maintain independently deployable, single-purpose AWS Lambda microservices in an event-driven architecture.
Develop Node.js Lambda services for intake, validation, transformation, submission, and acknowledgement handling of JSON, XLSX, and CSV transaction files.
Build event-driven services triggered by S3 notifications, EventBridge, SQS, and API Gateway, defining clear service contracts.
Use the AWS SDK for Node.js to integrate with AWS services including S3, DynamoDB, SNS/SES, Secrets Manager, and Step Functions.
Manage dependencies, Lambda layers, bundling, and Node.js function cold-start, memory, and timeout settings.
Define service boundaries and contracts, including event payloads, schemas, and S3 formats, to support independent development and deployment.
Maintain and extend AWS Glue ETL jobs using PySpark and native Oracle JDBC to ingest, transform, and reconcile daily transaction history and position snapshot files.
Build and troubleshoot Step Functions workflows for file validation, ingestion, reconciliation, and alerting.
Design and maintain Python and Node.js Lambda functions for orchestration, file validation, DynamoDB writes, and SNS/SES alerting.
Write and optimize Oracle SQL against a complex financial schema using native JDBC and Lambda-proxied access.
Manage DynamoDB data models for transaction history, reconciliation status, and fund-level summaries, including GSIs and TTL-based retention.
Implement error handling and transactional integrity, including per-record commit/rollback, idempotency, and duplicate detection.
Apply retries, dead-letter queues, and idempotency keys to prevent duplicate processing of repeated S3 events.
Own unit, integration, and smoke test suites and maintain or improve code coverage.
Support CI/CD pipelines, including build, test, lint, and packaging of Node.js services.
Build and maintain observability through structured CloudWatch logs and metrics, Grafana dashboards, and metric registries for pipeline health.
Participate in security reviews and remediate findings, including SQL injection protections, least-privilege IAM, KMS encryption, and Node.js dependency vulnerabilities.
Produce and maintain architecture references, runbooks, deployment guides, and changelogs.