https://www.duncanleung.com/blog 📚 Learning, 👨🏻‍💻 Building, 📝 Documenting... en-us duncan@leungs.email (Duncan Leung) duncan@leungs.email (Duncan Leung) Mon, 03 May 2021 00:00:00 GMT https://www.duncanleung.com/blog/golang-readers-writers https://www.duncanleung.com/blog/golang-readers-writers Understanding the io.Reader and io.Writer interfaces in Go, and how accepting an io.Writer parameter makes your code flexible across files, HTTP responses, stdout, and in-memory buffers. Mon, 03 May 2021 00:00:00 GMT duncan@leungs.email (Duncan Leung) backendgo https://www.duncanleung.com/blog/self-hosting-go-binary-aws-ec2-systemd https://www.duncanleung.com/blog/self-hosting-go-binary-aws-ec2-systemd Deploying a Go service to a single AWS EC2 instance as a hardened systemd service - cross-compiling the binary, copying it across, creating a non-root service user, configuring systemd with the right hardening directives, and handling graceful shutdown. Mon, 03 May 2021 00:00:00 GMT duncan@leungs.email (Duncan Leung) backendgoaws https://www.duncanleung.com/blog/iterating-index-strings-runes-go-golang https://www.duncanleung.com/blog/iterating-index-strings-runes-go-golang Understanding the difference between indexing strings as bytes versus runes in Go, and when to use each approach for proper Unicode handling. Wed, 16 Jun 2021 00:00:00 GMT duncan@leungs.email (Duncan Leung) backendgo https://www.duncanleung.com/blog/go-basic-data-structures-types-pointers-structs-arrays-slices-int-float-string https://www.duncanleung.com/blog/go-basic-data-structures-types-pointers-structs-arrays-slices-int-float-string Understanding Go data structures and their memory layout including integers, floats, arrays, pointers, structs, strings, and slices. Fri, 09 Jul 2021 00:00:00 GMT duncan@leungs.email (Duncan Leung) backendgo https://www.duncanleung.com/blog/understand-go-golang-interfaces https://www.duncanleung.com/blog/understand-go-golang-interfaces A guide to understand Go interfaces through a power socket and electrical device analogy, covering duck typing and interface implementation. Thu, 23 Dec 2021 00:00:00 GMT duncan@leungs.email (Duncan Leung) backendgo https://www.duncanleung.com/blog/go-function-arguments-passed-by-value https://www.duncanleung.com/blog/go-function-arguments-passed-by-value How Go passes function arguments by value and the implications for different data types: integers, pointers, slices, strings, and structs. Thu, 08 Jun 2023 00:00:00 GMT duncan@leungs.email (Duncan Leung) backendgo https://www.duncanleung.com/blog/go-json-encoding-and-decoding https://www.duncanleung.com/blog/go-json-encoding-and-decoding A guide to JSON serialization and deserialization in Go, covering type mappings, HTTP responses, and practical examples with the net/http package. Mon, 19 Jun 2023 00:00:00 GMT duncan@leungs.email (Duncan Leung) backendgo https://www.duncanleung.com/blog/slices-in-go https://www.duncanleung.com/blog/slices-in-go Understanding Go slices, their underlying array structure, creation and modification mechanics, and the implications when passing slices to functions. Mon, 26 Jun 2023 00:00:00 GMT duncan@leungs.email (Duncan Leung) backendgo https://www.duncanleung.com/blog/allocating-memory-go https://www.duncanleung.com/blog/allocating-memory-go Understanding memory allocation in Go, including stack vs heap allocation, escape analysis, and how Go handles pointer returns from functions. Wed, 28 Jun 2023 00:00:00 GMT duncan@leungs.email (Duncan Leung) backendgo https://www.duncanleung.com/blog/methods-in-go https://www.duncanleung.com/blog/methods-in-go Understanding Go methods, the difference between value and pointer receivers, embedding for composition, and how interfaces work with methods. Wed, 28 Jun 2023 00:00:00 GMT duncan@leungs.email (Duncan Leung) backendgo https://www.duncanleung.com/blog/go-idiom-accept-interfaces-return-types https://www.duncanleung.com/blog/go-idiom-accept-interfaces-return-types Understanding the Go idiom of accepting interfaces and returning concrete types to write flexible, reusable, and maintainable code. Fri, 30 Jun 2023 00:00:00 GMT duncan@leungs.email (Duncan Leung) backendgo https://www.duncanleung.com/blog/go-interface-segregation-shared-singletons https://www.duncanleung.com/blog/go-interface-segregation-shared-singletons When one Go struct legitimately serves multiple consumer roles - producer, service, admin - declare three interfaces and let DI cache the singleton at the wide type while each consumer holds only the methods it can call. Same shape as io.ReadWriteCloser in the stdlib. Thu, 30 Apr 2026 00:00:00 GMT duncan@leungs.email (Duncan Leung) backendgo https://www.duncanleung.com/blog/postgres-where-status-idempotent-sqs-worker https://www.duncanleung.com/blog/postgres-where-status-idempotent-sqs-worker Most SQS idempotency guides reach for Redis dedupe keys or dedupe tables. If your worker's job ends in a terminal state-machine transition, the row's own status column is already the lock - and one UPDATE statement is the entire safety story. Thu, 30 Apr 2026 00:00:00 GMT duncan@leungs.email (Duncan Leung) backendgoawspostgres https://www.duncanleung.com/blog/nextjs-module-load-env-guards-structural-validation https://www.duncanleung.com/blog/nextjs-module-load-env-guards-structural-validation Most env-var validation checks that values exist. That catches missing config but misses the worse case - a value that is present, valid in shape, and silently wrong. Here is the asymmetric pattern for separating loud failures from silent ones in a Next.js server. Tue, 12 May 2026 00:00:00 GMT duncan@leungs.email (Duncan Leung) nextjstypescriptbackendsecurity