spring-launch-monitor

A plug-and-play Spring Boot startup monitor that captures startup phases and bean initialization timing, then outputs a readable startup report plus flame-tree artifacts.

📷 Screenshot

Expend/Collapse Screenshot

Report Package Flame Tree

😄What It Provides

• Startup timeline capture (from early boot phases to ready).
• Bean initialization timing collection.
• Console startup report (plain text).
• Optional flame folded output to console.
• HTML flame tree report for visual diagnosis.
• Compact JSON tree output for custom dashboards/tools.

⚙️ Principle

• Early startup events are captured through Spring Boot lifecycle listeners (for example starting/environment/context/ready phases).
• Bean initialization timing is collected through BeanPostProcessor hooks and aggregated as startup records.
• Data is split into two output lanes:
  • Console: lightweight plain-text report (stable and charset-friendly).
  • Artifacts: HTML (rich i18n report + flame tree) and JSON (compact package tree for tooling).
• Package-level flame tree is built by aggregating bean class package segments (for example org -> springframework -> ...) with cumulative latency.

👉 How To Use

1) Add Dependency

Use your published coordinate (default example below). Replace 0.0.1 with the latest release from Maven Central before use:

dependencies {
    implementation "io.github.danburen:spring-launch-monitor:0.0.1"
}

Important

Building Environment:

Java JDK 22

Groove Gradle: 9.4.0+

SpringBoot 4.0.4

If you publish locally first, see How To Build and Use From Another Local Project.

2) Add Configuration (Optional)

launch:
  monitor:
    enable: true
    report: true
    flame:
      console: false
      html: true
      json: true
    output-dir: build/reports/spring-launch-monitor
    locale: auto

3) Start Application

At ApplicationReadyEvent, the monitor will:

• Print console report (when launch.monitor.flame.console=true).
• Print folded flame output (when flame.console=true).
• Write artifacts (depending on flame.html/json):
  • flame-tree.html
  • flame-tree.json

Configuration Reference

• launch.monitor.enable Master switch; default true.
• launch.monitor.report Console startup report switch; default true.
• launch.monitor.flame.console Console folded flame output; default false.
• launch.monitor.flame.html Write HTML flame tree artifact; default true.
• launch.monitor.flame.json Write JSON flame tree artifact; default true.
• launch.monitor.output-dir Output directory for generated artifacts.
• launch.monitor.locale i18n locale for HTML/report labels, e.g. auto, en-US, zh-CN.

Legacy Compatibility Keys

Currently still recognized for compatibility:

• launch.monitor.report.enabled
• launch.monitor.flame.enabled

Prefer new keys under launch.monitor.flame.*.

Output Files

By default, files are generated under:

build/reports/spring-launch-monitor

• flame-tree.html Rich report + package flame tree visualization.
• flame-tree.json Compact package tree JSON.

🧱 How To Build

Build Library

./gradlew.bat clean build

Run Tests

./gradlew.bat test

📑 License

See LICENSE.