Automate MinIO Image Cleanup with Spring Boot Scheduled Tasks

Overview

The project stores images in MinIO and needs a periodic cleanup to remove files older than a configurable date, reducing storage costs.

Dependencies

Only MinIO SDK and Spring Boot starter are required.

<dependency>
  <groupId>io.minio</groupId>
  <artifactId>minio</artifactId>
  <version>8.5.1</version>
</dependency>

Delete Utilities

The MinioUtil class provides methods to delete entire date folders and single prefixes.

public int deleteDateFoldersBefore(LocalDate endExclusive) { ... }
private int deleteSingleFolder(String prefix) { ... }

Performance Tips

Use listObjects pagination (default 1000 items).

Iterate removeObjects results to trigger HTTP calls.

Limit batch size with .maxKeys(batchSize) for massive object sets.

Scheduled Task Configuration

Enable scheduling with @EnableScheduling and define a cron expression.

@Scheduled(cron = "0 0 3 1 * ?")
public void minioClean() { ... }

Cron Expression Details

Field

Range

Special Characters

Second

0‑59

, - * /

Minute

0‑59

, - * /

Hour

0‑23

, - * /

Day

1‑31

, - * / ? L W

Month

1‑12 or JAN‑DEC

, - * /

Weekday

0‑7 (SUN‑SAT)

, - * / ? L #

Thread‑Pool Tuning

Spring’s ThreadPoolTaskScheduler can be customized to avoid task blocking.

ThreadPoolTaskScheduler scheduler = new ThreadPoolTaskScheduler();
scheduler.setPoolSize(3);
scheduler.setThreadNamePrefix("minio-scheduler-");
...

Rejection Policies

AbortPolicy

– throws exception. CallerRunsPolicy – runs task in caller thread. DiscardPolicy – silently drops task. DiscardOldestPolicy – drops oldest queued task.

Asynchronous Execution

Define an async executor with @EnableAsync and annotate the cleanup method with @Async("taskExecutor") to prevent scheduler thread blockage.

@Async("taskExecutor")
@Scheduled(cron = "0 0 3 1 * ?")
public void minioClean() { ... }

Configuration Extensions

Externalize settings in application.yml (enabled, retain‑days, earliest‑date, cron) and bind them to a MinioCleanProperties class.

minio:
  clean:
    enabled: true
    retain-days: 5
    earliest-date: "2025/08/01"
    cron: "0/5 * * * * ?"

Testing

Use a JUnit test to invoke deleteDateFoldersBefore with a custom date, ensuring files exist before the run.

@SpringBootTest
class MinioTest {
  @Autowired MinioUtil minioUtil;
  @Test void testDelete() {
    int count = minioUtil.deleteDateFoldersBefore(LocalDate.of(2025,8,2));
    System.out.println(count);
  }
}