--- title: "Latest reads" description: "The engineering internet, summarised so you can actually read it." --- # Latest reads > The engineering internet, summarised so you can actually read it. ## Articles ### [The science of routing print orders](https://yomu.fyi/post/the-science-of-routing-print-orders.md) - Company: [Canva](https://yomu.fyi/company/canva.md) - Author: Constantinos Kavadias - Published: Dec 10, 2024 Canva's global print network requires selecting optimal suppliers to balance delivery times, packaging counts, and environmental emissions. To resolve these challenges before user checkout, the engineering team designed a modular routing architecture that decouples graph construction, decision logic, and path traversal. During graph traversal, the system generates action objects capturing forward paths and decision query results, which are compiled into timestamped routing logs in blob storage for asynchronous auditing. Utilizing preprocessed graph queries alongside ElastiCache, Redis, and database read replicas, the infrastructure sustains high-throughput evaluation without coupling cost logic to traversal code. As a result, print routing completes within an average of 50 milliseconds at the 99th percentile during peak usage while maintaining 99.999% data availability. ### [Enhance your monitoring by integrating Stripe events with AWS CloudWatch Log Groups](https://yomu.fyi/post/enhance-your-monitoring-by-integrating-stripe-events-with-aws-cloudwat.md) - Company: [Stripe](https://yomu.fyi/company/stripe.md) - Author: Andrew Robinson - Published: Dec 9, 2024 Stripe events notify account owners about changes such as successful charges, failed invoice payments, and available reconciliation reports. Because Stripe retains events for 13 months but exposes older events than 30 days only as summaries, Amazon EventBridge can route them into an AWS account and Amazon CloudWatch Log Groups can provide longer-term monitoring and analysis. The setup uses CloudWatch metric filters to match event types such as invoice.payment\_failed, convert matches into custom metrics, and support alarms, Amazon SNS notifications, dashboards, and Logs Insights queries. For example, a failed-invoice alarm can use a five-minute observation period, Sum statistics, and a threshold based on expected failure volume or anomaly detection. The resulting setup supports near-real-time visibility into successful charges and failed payments, historical trend analysis, troubleshooting, and responses to unusual activity. ### [How we seamlessly migrated high volume real-time streaming traffic from one service to another with zero data loss and duplication](https://yomu.fyi/post/how-we-seamlessly-migrated-high-volume-real-time-streaming-traffic-fro.md) - Company: [Grab](https://yomu.fyi/company/grab.md) - Author: Md Riyadh - Published: Dec 5, 2024 Grab split a backend service's read and write functionalities into separate services to allow independent scaling. Migrating the write path required transferring processing from 16 source Kafka streams—averaging 20,000 reads per second into DynamoDB tables and output streams—with zero data loss or duplication. Standard feature flags were ruled out because rollout propagation delays could introduce minutes of duplicate or missing data during flag toggling. Instead, engineers extracted processing logic into a shared monorepo commons package that used coordinated timestamps to trigger simultaneous cutovers across both services. Temporary validation sinks verified processing accuracy in production prior to the cutover, completing the stream-by-stream migration across three weeks without downtime. ### [Supercharging LLM application development with LLM-Kit](https://yomu.fyi/post/supercharging-llm-application-development-with-llm-kit.md) - Company: [Grab](https://yomu.fyi/company/grab.md) - Author: Boon Zhan Chew - Published: Nov 29, 2024 Grab developed LLM-Kit to resolve standardization, security, observability, and infrastructure provisioning bottlenecks across its generative AI development efforts. Submitting an initial application request automatically triggers project generation in GitLab, outputting a modular codebase along with Terraform definitions for Amazon EKS and ECR. The scaffolded architecture incorporates FastAPI, LangChain, OpenID Connect authentication helpers, and PGVector alongside HashiCorp Vault for credential management. Observability and quality tracking are built in through direct integrations with Datadog and LangSmith evaluations. By providing these standardized paved-road templates, the framework has onboarded hundreds of generative AI applications and saved teams an estimated 1.5 weeks of initial setup time. ### [Data access patterns for simple Stripe integrations](https://yomu.fyi/post/data-access-patterns-for-simple-stripe-integrations.md) - Company: [Stripe](https://yomu.fyi/company/stripe.md) - Author: Ben Smith - Published: Nov 27, 2024 The article examines how applications should store and access product data in simple Stripe integrations as requirements for security, performance, and scalability evolve. It compares using Stripe’s built-in product fields with a separate database, while explaining that publishable API keys cannot retrieve product details and that secret or restricted keys must remain server-side. A web backend or serverless function can proxy requests securely, while CloudFront caching reduces repeated calls and latency but requires an appropriate refresh cadence. For richer metadata, inventory, variants, or custom attributes, the article describes combining DynamoDB with Lambda and Stripe, using Event Destinations or webhooks to synchronize changes and weighing that flexibility against database overhead. ### [Managing multiple Stripe test environments from your AWS-hosted application](https://yomu.fyi/post/managing-multiple-stripe-test-environments-from-your-aws-hosted-applic.md) - Company: [Stripe](https://yomu.fyi/company/stripe.md) - Author: James Beswick - Published: Nov 26, 2024 Stripe sandboxes provide isolated test accounts that let teams manage multiple environments from one account. Unlike legacy test mode, each sandbox has separate data, its own API keys, and configurable user access, while up to five sandboxes can exist per account. They support simulated external events, fake balances, Test Payouts with API v2 keys, and CLI or SDK access by changing keys. For AWS-hosted applications, the recommended pattern stores sandbox and production keys in AWS Secrets Manager, using secret names as environment-neutral aliases rather than embedding environment logic in code. Teams can combine Stripe sandbox permissions with AWS IAM resource policies and directory groups to restrict which users or accounts can retrieve keys and prevent accidental production access. ### [Getting started with Stripe in the UAE: A comprehensive guide for developers](https://yomu.fyi/post/getting-started-with-stripe-in-the-uae-a-comprehensive-guide-for-devel.md) - Company: [Stripe](https://yomu.fyi/company/stripe.md) - Author: Soad Abuelnaga - Published: Nov 25, 2024 The guide explains how developers can use Stripe for UAE-based e-commerce businesses, following its public debut in the country in April 2021. It covers Stripe Billing for recurring billing, Stripe Connect for marketplaces, Stripe Radar's machine-learning fraud protection, and the platform's support for Apple Pay, Google Pay, and more than 135 currencies including AED, BHD, and KWD. Account setup requires business details, KYC documentation based on entity type, and a linked bank account, with sole proprietors and free zone establishments allowed to use personal accounts under the stated conditions. The Dashboard supports payout and transaction tracking, customer and product management, real-time updates, data exports, tax configuration, and Payment Links, while UAE payouts are described as arriving in AED or USD on a T+5 business-day schedule. ### [How we reduced initialisation time of Product Configuration Management SDK](https://yomu.fyi/post/how-we-reduced-initialisation-time-of-product-configuration-management.md) - Company: [Grab](https://yomu.fyi/company/grab.md) - Author: Ram Dilip Pradhan - Published: Nov 22, 2024 GrabX operates as Grab's central platform for product configuration management, where client services fetch configuration data via an eventually consistent SDK. Services handling around 400 MB of configuration data experienced startup cold starts taking approximately four minutes, creating service stress during traffic spikes. The engineering team resolved this bottleneck through a multi-phase optimization of how the SDK retrieves data from AWS S3. First, sequential downloads of common and service-specific datasets were replaced with concurrent fetching. Next, concurrent downloading and memory loading were applied across large configurations within subscribed services, followed by the complete removal of an outdated disk-caching fallback mechanism. Benchmarks across diverse configuration payloads showed an overall initialisation time reduction of up to 90%. ### [Using demo data for testing Stripe integrations in AWS-hosted applications](https://yomu.fyi/post/using-demo-data-for-testing-stripe-integrations-in-aws-hosted-applicat.md) - Company: [Stripe](https://yomu.fyi/company/stripe.md) - Author: James Beswick - Published: Nov 22, 2024 Stripe sandboxes let developers manage multiple test environments from one Stripe account for AWS-hosted applications, extending Stripe’s test mode with simulated external events, fake balances, and Test Payouts using API v2 keys. The post describes seeding a sandbox with products and other Stripe objects by exporting production data to CSV for import or generating records with the Stripe CLI and scripts. For local use, developers authenticate with stripe login, while CI scripts pass a sandbox key to each CLI request and can optionally delete the created products afterward. It recommends storing the key in AWS Secrets Manager, retrieving it at runtime through the AWS CLI or SDK, restricting access with IAM, avoiding logs and source repositories, and rotating keys; this lets CI scripts use sandbox data without exposing credentials. ### [Avoiding silent errors in your Stripe integration](https://yomu.fyi/post/avoiding-silent-errors-in-your-stripe-integration.md) - Company: [Stripe](https://yomu.fyi/company/stripe.md) - Author: Abe Haskins - Published: Nov 21, 2024 Stripe integrations can appear healthy while API and webhook failures accumulate unnoticed when applications lack robust logging and alerting. The post demonstrates Stripe Workbench, a Dashboard view that stores available information by default, obfuscates sensitive data, and provides searchable logs without code changes or additional software. In the example, about 50% of daily API calls fail; the Errors tab groups failures and connects each type to sample requests and related logs, revealing repeated card-verification errors and a request associated with an “Attacker Engineering Test Key” whose Go user-agent conflicted with the stated .NET backend. The investigation identifies a team testing attack-like API calls in production and recommends stopping production-key testing, avoiding test requests in production, and using Sandboxes. ### [How Tinder Eased Development Pain With Ignis](https://yomu.fyi/post/how-tinder-eased-development-pain-with-ignis.md) - Company: [Tinder](https://yomu.fyi/company/tinder.md) - Author: Tinder - Published: Nov 15, 2024 Managing hundreds of microservices with disparate configurations forced Tinder engineers to deploy code to staging environments to verify every change, slowing development velocity. To shorten feedback loops, the team created Ignis, a Go-based CLI tool that lets engineers run an isolated service locally while proxying ingress and egress traffic through a multi-tenant development Kubernetes cluster. Ignis pairs with an API gateway for client testing and uses a custom Smart Router proxy to dynamically intercept downstream gRPC and HTTP requests via Kubernetes informers and header propagation. Since launching in 2019, the tool enabled Tinder to eliminate a dozen staging environments, decrease cloud spend, and accelerate onboarding, followed by a V2 release adding remote IDE support and monitoring. ### [Metasense V2: Enhancing, improving and productionisation of LLM powered data governance](https://yomu.fyi/post/metasense-v2-enhancing-improving-and-productionisation-of-llm-powered.md) - Company: [Grab](https://yomu.fyi/company/grab.md) - Author: Nick Buhrer - Published: Nov 14, 2024 Grab scaled Metasense to automate metadata generation, column-level classification, and sensitivity tiering across its entire data lake. Post-rollout analysis revealed that high tag volumes, wide tables, and mixed content—such as nested JSON and customer communications—strained model capacity and led to missed Personally Identifiable Information (PII). To overcome these limitations, the team split the classification process into distinct PII and non-PII tasks, reduced prompt word counts, and partitioned tables with over 150 columns into smaller units. Integrating LangChain and LangSmith modernized the architecture by enabling direct prompt experimentation, custom metric tracking, and version-controlled deployments. The updated pipeline achieved low misclassification rates alongside automated alert thresholds to trigger model improvement protocols if errors increase. ### [Adding payments to your LLM agentic workflows](https://yomu.fyi/post/adding-payments-to-your-llm-agentic-workflows.md) - Company: [Stripe](https://yomu.fyi/company/stripe.md) - Author: Steve Kaliski - Published: Nov 14, 2024 Agentic workflows combine large language models with function calling to turn prompts into sequences of actions, but connecting those actions to financial services requires controlled API access. The Stripe agent toolkit integrates Stripe with Vercel’s AI SDK, LangChain, and CrewAI, supports function-calling LLM providers, and is built on Stripe’s Node.js and Python SDKs. It exposes configurable tools for tasks such as invoicing, creating and sharing payment links, and using Issuing virtual cards with spending limits, authorization checks, and deactivation after purchase. Middleware can record input and completion token counts as billing events for usage-based customer billing. Because agent behavior is non-deterministic, the post recommends test mode, evaluations, restricted keys, limited tool sets, and reduced request and response shapes to improve focus and constrain failures. ### [Developing and investigating subscription data flow](https://yomu.fyi/post/developing-and-investigating-subscription-data-flow.md) - Company: [Stripe](https://yomu.fyi/company/stripe.md) - Author: Hidetaka Okamoto - Published: Nov 13, 2024 The article presents Stripe Sandboxes as isolated environments for developing and investigating subscription systems without affecting production data or settings. It explains how to create subscriptions, inspect dashboard actions through Workbench, and review API requests, JSON resource data, and webhook events such as customer.subscription.created and invoice.created. Test Clocks allow developers to advance time and examine subscription cancellation behavior, including the customer.subscription.deleted event after a scheduled cancellation. Workbench’s Shell tab, API Explorer, and Print SDK Request feature support testing requests in the browser and converting them into implementation code, while the article stresses testing plan changes, trial expirations, cancellations, and payment failures. ### [Growing your Stripe integration With Event Destinations](https://yomu.fyi/post/growing-your-stripe-integration-with-event-destinations.md) - Company: [Stripe](https://yomu.fyi/company/stripe.md) - Author: Ben Smith - Published: Oct 31, 2024 Stripe Event Destinations, now in general availability and rolling out to all accounts, lets companies extend payment workflows without changing existing integrations. The post explains how Stripe events can be sent either to an AWS account through Amazon EventBridge or to a webhook endpoint, with EventBridge routing selected events to services such as AWS Lambda, Step Functions, and SQS. Event filtering, logging, transformation, and built-in security reduce the need to operate webhook servers and verify signatures in application code. Serverless Lambda functions can add custom logic and connect to DynamoDB, S3, or SNS, supporting examples including date-limited memberships, partial student payments, and real-time tipping broadcasts through AWS IoT Core and WebSockets. The resulting architecture is presented as flexible and scalable for variable or growing event volumes while preserving the underlying Stripe integration. ### [Managing SaaS access control with Stripe’s Entitlements API](https://yomu.fyi/post/managing-saas-access-control-with-stripe-s-entitlements-api.md) - Company: [Stripe](https://yomu.fyi/company/stripe.md) - Author: Hidetaka Okamoto - Published: Oct 31, 2024 Managing access rights across multiple SaaS pricing plans can require maintaining feature lists, subscription and pricing relationships, and related database resources as plans or features change. The post presents Stripe’s Entitlements API as a way to register features, associate them with Stripe Products, and retrieve active entitlements for a customer’s subscriptions. Its example defines Free, Personal, and Business monthly products priced at $0, $98, and $980, then maps article-viewing and business-report features to those products using Stripe CLI commands in Workbench. Customer entitlement checks can support application authorization, while entitlements.active\_entitlement\_summary.updated webhooks expose before-and-after permission data for workflows triggered by plan changes or cancellations. ### [How we reduced peak memory and CPU usage of the product configuration management SDK](https://yomu.fyi/post/how-we-reduced-peak-memory-and-cpu-usage-of-the-product-configuration.md) - Company: [Grab](https://yomu.fyi/company/grab.md) - Author: Ram Dilip Pradhan - Published: Oct 30, 2024 Grab's central product configuration management platform, GrabX, previously aggregated all configurations across every backend service into a single JSON file hosted on AWS S3. Every minute, client SDKs fetched, parsed, and loaded this growing file—which exceeded 100MB—causing CPU throttling spikes, elevated P99 latency, and unnecessary memory consumption. Analysis revealed that 98% of services required less than 1% of the total configuration data. To resolve these bottlenecks, the team partitioned data by service, split configurations into separate S3 files under distinct prefixes, and introduced a per-service changelog for incremental updates. Benchmarks showed the redesign decreased maximum CPU utilisation by over 50% and reduced memory usage by up to 70%. ### [Preparing for Stripe API upgrades](https://yomu.fyi/post/preparing-for-stripe-api-upgrades.md) - Company: [Stripe](https://yomu.fyi/company/stripe.md) - Author: Cecil Phillip - Published: Oct 24, 2024 Upgrading a third-party API can bring new features and fixes but may also introduce breaking changes, so applications should be evaluated before production changes. Stripe Sandboxes provide isolated test accounts with separate API keys and access controls, optionally copying production configuration without copying products, customers, or transaction data. The workflow uses Dashboard Workbench to inspect and upgrade the sandbox API version, then runs the application with sandbox credentials and forwards webhook events through the Stripe CLI. In the example, Stripe.net 41.0.0 rejected an event because it expected API version 2022-11-15 while the sandbox delivered 2024-09-30.acacia; upgrading the SDK to 46.0.0 resolved the mismatch. ### [LLM-assisted vector similarity search](https://yomu.fyi/post/llm-assisted-vector-similarity-search.md) - Company: [Grab](https://yomu.fyi/company/grab.md) - Author: Md Riyadh - Published: Oct 23, 2024 Vector similarity search often struggles with conceptual nuances, negations, and complex constraints despite its efficiency in high-dimensional semantic retrieval. To address this limitation, a two-step retrieval pipeline combines Facebook AI Similarity Search (FAISS) using OpenAI's text-embedding-ada-002 embeddings with a large language model re-ranking step powered by GPT-4o. The initial FAISS search extracts a candidate shortlist of matches, which GPT-4o then re-ranks based on contextual relevance and query intent. Evaluations on structured datasets showed that while simple queries yielded comparable results across methods, the LLM-assisted approach effectively resolved negations and conceptual matching where raw vector search failed. Internal production trials on relational datasets exceeding 4,500 rows demonstrated similar relevance improvements, with additional query latency being the primary operational trade-off. ### [Optimize payment flow while reducing code complexity with Stripe's A/B Testing](https://yomu.fyi/post/optimize-payment-flow-while-reducing-code-complexity-with-stripe-s-a-b.md) - Company: [Stripe](https://yomu.fyi/company/stripe.md) - Author: Hidetaka Okamoto - Published: Oct 23, 2024 Payment method choices affect ecommerce conversion, and the post notes that 81% of surveyed customers frequently abandon carts when their preferred method is unavailable. It explains how Stripe’s dynamic payment methods in Elements and Dashboard settings can apply country, region, and amount rules without embedding those conditions in PaymentIntent code. The proposed workflow uses Dashboard experiments to enable methods such as Klarna, set display rules and traffic allocation, then uses Workbench Inspector, Logs, and Events tabs to inspect presented payment\_method\_types, API requests, and webhook history. A Klarna example reports a 16% increase in average order value, while new payment methods were deployed within four days. [Newer posts](https://yomu.fyi/page/35.md) · [Older posts](https://yomu.fyi/page/37.md)