asmhatre
320733265f
Companion module for the rewritten post 'Resilience4j Circuit Breaker in Spring Boot 4.1: What It's Still For', reworked around Framework 7 now shipping @Retryable/@ConcurrencyLimit in core. Covers what's still Resilience4j's job (circuit breaker, rate limiter, bulkhead's bounded wait, fallback methods, Actuator/Micrometer metrics), the off-by-one between maxAttempts and maxRetries, and two Boot-4.1 build breaks: spring-boot-starter-aop no longer exists (renamed to spring-boot-starter-aspectj, proven with Maven Central metadata and the renamed starter's own POM -- see resilience/docs/08-starter-aop-renamed-to-starter-aspectj.md in this same repo), and the resulting fix uses that renamed starter directly rather than assembling spring-aop + aspectjweaver by hand. Kept as its own module rather than a new top-level repository, alongside the existing resilience/ module for the sibling Framework-7 post.
spring-boot-demo
Companion code for the Spring Boot articles on ankurm.com.
One directory per article. Each is a self-contained Maven project with its own README.md,
numbered documentation chapters under docs/, and captured real output under docs/output/
that a single script regenerates. Every figure quoted in an article came out of one of those
files.
| Directory | Article | What it demonstrates |
|---|---|---|
actuator-in-production/ |
Spring Boot Actuator in Production | endpoint exposure defaults, securing Actuator, custom health indicators and how they hang |
spring-boot-startup-time/ |
Why Your Spring Boot App Takes 8 Seconds to Start | BufferingApplicationStartup, JFR startup events, self time vs total time, the classpath-scan tax, the JDK 25 AOT cache |
configuration-properties/ |
@ConfigurationProperties vs @Value in Spring Boot 4 | relaxed binding measured three ways, record constructor binding, validation, IDE metadata generation |
profiles-and-config/ |
Spring Boot Profiles Done Right | the precedence stack made visible, config trees and ConfigMaps, why a profile file loses to an environment variable |
spring-aop/ |
Spring AOP Explained | every pointcut designator with real matches, JDK vs CGLIB proxies, six aspects that do not fire |
docker-images/ |
Dockerizing Spring Boot 4: Layered Jars, Buildpacks, Distroless and Image Size Benchmarks | one service packaged nine ways and measured: size on disk and pushed, rebuild delta, startup, PID 1 and signals, jlink, the JDK 25 AOT cache |
kubernetes-deployment/ |
Deploying Spring Boot 4 on Kubernetes | probe groups under a dependency outage, graceful shutdown under load four ways, JVM ergonomics per pod shape, CPU limits throttling GC, HPA on a Micrometer metric |
problem-details/ |
Global Exception Handling with ProblemDetail (RFC 9457) in Spring Boot 4 | thirteen failures under five handling setups, validation errors, i18n, content negotiation, errors outside MVC, silent 500s, decoding on the client |
resilience/ |
Spring Framework 7's Built-in Resilience: @Retryable, @ConcurrencyLimit, and What's Left for Resilience4j | @Retryable and @ConcurrencyLimit counted invocation by invocation, retries inside transactions, where Resilience4j still earns its place, migrating from Spring Retry |
caching/ |
The Spring Cache Abstraction: @Cacheable, @CacheEvict, Key Generators and the Self-Invocation Trap | the self-invocation trap measured four ways, the key collision SimpleKeyGenerator makes easy, eviction timing under a thrown exception, a rollback the cache keeps, and where this sits next to Hibernate's L2 cache |
spring-batch/ |
Spring Batch on Boot 4.1: Jobs, Steps, Chunk Processing and Restartability | a job that fails mid-chunk and resumes exactly where it left off across two separate JVMs, skip vs. restart on the same poisoned row, the resourceless job repository that forgets a restart ever happened, and the chunk(int) vs chunk(int, tx) builder split |
spring-batch-partitioning/ |
Spring Batch Partitioning and Parallel Steps: Scaling a 10-Million-Row Job | the real grid-size sweep at 10M and 300K rows (best speedup 1.42x, on 2 cores), MultiResourcePartitioner ignoring gridSize entirely, a rejected partition's StepExecution stuck at STARTING forever, and Spring Batch 6.0's new JobOperator#recover unsticking it |
db-migrations-flyway-liquibase/ |
Flyway vs Liquibase for Spring Boot 4: Migrations, Rollbacks and Baselines | Flyway Community's undo throwing FlywayRedgateEditionRequiredException at runtime, a real Liquibase 5.0.3 filename-caching defect that produces a phantom successful run, Liquibase's 10-second default lock-poll rate versus Flyway's near-instant row lock, the FSL license change and its ASF/Keycloak fallout, and what actually happens when both tools are enabled against one database |
db-migrations-expand-contract/ |
Zero-Downtime Database Migrations: Expand-Contract in Practice with Spring Boot | a real 4-deploy rolling sequence against two live replicas with a load generator proving 99.98% success, H2's AUTO_SERVER single-point-of-failure trap, a NOT NULL constraint that fails every Stage 4 insert, and ALTER TABLE silently dropping a concurrently committed row with no exception thrown |
openapi-versioning/ |
springdoc-openapi with Spring Boot 4.1: Generating, Customising and Versioning Your API Spec | springdoc 3.1.1 silently merging same-path, different-version handlers into one oneOf operation with an arbitrary operationId, a working per-version fix with GroupedOpenApi + OpenApiCustomizer, and the officially-versioning-supported functional-endpoint path turning out to document only one of two registered versions |
graphql-dataloader/ |
Spring GraphQL 2.0: Schema-First APIs, DataLoader Batching and Killing N+1 | a naive @SchemaMapping resolver measured at 21 SQL statements for 20 books versus a @BatchMapping resolver's flat 2, a dangling foreign key nulling an entire GraphQL response via non-null propagation identically under both resolver strategies, and two Spring Boot 4.1 packaging changes (DataSourceAutoConfiguration's new package, Jackson 3 by default) hit along the way |
Articles whose text is kept here rather than only on the blog have it under
<directory>/post/ — post.md for the body and meta.md for the title, excerpt and
categories.
Running any of them
Each project needs a JDK 25 and Maven 3.9. docker-images also needs Docker, and
kubernetes-deployment Docker plus a Kubernetes cluster; their READMEs list the rest:
cd <directory>
export JAVA_HOME=/path/to/jdk-25
mvn -DskipTests package
./scripts/run-all.sh # regenerate every transcript under docs/output/
Licence
MIT — see LICENSE.