Sungwon Cho (also known as Sam Jo; 뀨냥이)

Match Group

Site Reliability Engineer • 2023-05 — Present

I am currently working on the Central Platform Technology & Service (CPTS) team.

I -

• Build and introduce several internal systems for the team and all developers of MG brands, including central documentation, monitoring, artifact storage, and ticketing systems.
• Introduce monitoring systems and on-call cultures to the team, along with documentations; 100% of internal applications now use these new monitoring systems.
• Build internal tools and systems for developers, such as a CLI to login the AWS accounts with ECR, decrypt data for debugging, generate authentication tokens, and more.
• Standardize procedures in infrastructure-related topics, such as Terraform / Terragrunt codes, tag policies, billing reports, AWS account management and so forth.
• Coordinate closely with the security team on matters related to AWS resources and third-party integration management, including cross-team reviews, R&R discussions and migrations.
• Lead a few migration projects (CDNs, internal VPNs, etc.) within the team, participate in all steps, including initial PoC, developing migration plans, actual migration, and documentation.
• Develop the hiring process, take-home assignments, pre-screen and interview questions to hire backend engineers for the team; participate in interviews.

Hyperconnect

DevOps Engineer • 2019-04 — 2023-04

As a core member of the DevOps team, I played a significant role in building and enhancing overall infrastructure.

I -

• Migrated ~50% of Kubernetes workloads to ARM64 (Graviton) based nodes.
• Introduced Kubernetes and Istio to production services including Azar, Hakuna; helped developers migrate EC2 based legacy microservices to Kubernetes.
• Deployed 30+ Kubernetes clusters for production, development, and management, and also deployed infrastructure components, including cluster-autoscaler, node-exporter and Zabbix agents.
• Developed and managed CI/CD pipelines for 300+ microservices across 5+ products and 4+ environments using Spinnaker, Github Action, Jenkins, Helm, and Vault.
• Provided an automated monitoring and alerting system using Prometheus, Mimir, Grafana, and Zabbix; developed a GitOps system to configure alert conditions and thresholds that covers > 90% of alerts.
• Researched and executed PoC, including adopting Istio, Vault, Mimir, SonarQube, Bottlerocket, and Harbor to production; found zero-downtime upgrade paths for Kubernetes, Istio, and other components.
• Upgraded certain legacy systems, including OS, Kubernetes, Jenkins, and Zabbix; transitioned VPC peerings to inter-region peered transit gateways.
• Developed a GitOps-based permission management system using Okta, Active Directory, and AWS SSO with 30+ accounts, AWS Client VPN with 50+ VPCs. This system was also integrated with JetBrains IDE products, Grafana, and Harbor.
• Developed management tools and helpful internal CLIs, including a production database query executor, Spinnaker pipeline generator, and configuration/credentials fetcher for multiple AWS accounts and Kubernetes clusters.
• Participated in several rebuilding projects of business-critical microservices; set up initial architectures with developers to meet high-availability and multi-regional requirements.
• Served in the capacity of a site reliability engineer; had on-call duty for Azar and common infrastructures, planned and trained for disaster recovery with an AWS region failure scenario.
• Assisted the security team in achieving SOX compliance in our systems, including CI/CD and access management.
• Contributed to some open source projects, including Bottlerocket, aws-ebs-csi-driver and Istio.
• Wrote 10+ tech blog articles (in Korean), 50+ internal manuals and tutorials; and gave public presentations - EKS Cluster Migration (in Korean) and Microservice CI/CD (in Korean).

Vonvon

Developer • 2018-06 — 2019-04

I developed an automated ads manager, and migrated a set of APIs.

I -

• Made an automated ads manager; it automatically creates ads from the content management tools, measures various metrics (CPC, ROI, etc.) using Google DFP and Facebook Ad APIs, changes their budgets depending on the metrics.
• Migrated a set of image processing APIs from Google AppEngine to Google Kubernetes Engine.
• Organized duplicate build and deploy scripts in many git repositories.

Lendit

Software Engineer • 2017-07 — 2018-05

I developed various features for Lendit's web service, back office and infrastructures.

I -

• Improved build and deploy infrastructures for automatic deployments using Travis CI and AWS CodeDeploy.
• Refactored and optimized codes; removed a lot of legacy from both backends and frontends (converting Java Date to LocalDate and LocalDateTime, converting JSP pages to Vue, converting Java to Kotlin).
• Coded an program to transfer telegram to Shinhan bank using Python 3.6 + aiohttp.
• Opened a tech blog and posted work-related articles including interviews and the build infrastructures.

Security @ NAVER Corp.

Undergraduate Intern • 2017-01 — 2017-06

I participated in small projects related to security issues.

I -

• Improved TLS/SSL vulnerabilities scanner in terms of accuracy and speed using Go.
• Made a dynamic crawler and an reflected XSS detector using headless Chrome.

SysSec Lab. @ KAIST GSIS

Undergraduate Intern • 2016-02 — 2016-12

I participated in a lab project.

I -

• Developed a TLS/SSL vulnerabilities scanner using Python.
• Performed static and dynamic analyze of Android apps.

KAIST (Korea Advanced Institute of Science and Technology)

Bachelor's Degree, School of Computing • 2014 Spring — 2021 Fall

• Graduate (2021 Fall)
• Mandatory military service as industrial technical personnel (산업기능요원, 2017 Spring — 2021 Spring)
• CS101 TA (2016 Fall)
• Honor Student (2016 Spring — 2021 Fall)
• Dean's List (2015 Spring)
• School of Computing (2015 Spring — 2021 Fall): student, taken courses
• SPARCS (2014 Spring — 2021 Fall): staff (2016), developer and wheel (server manager)