Bazel rules for Spring AOT

Bazel rules for building Spring applications with Ahead-of-Time (AOT) compilation support. These rules enable you to leverage Spring's AOT processing capabilities within your Bazel build, resulting in faster startup times and reduced memory footprint for your Spring applications.

Features

• 🚀 Faster Startup: Pre-process Spring beans and configurations at build time
• 💾 Reduced Memory: Lower runtime memory usage through AOT optimizations
• 🔧 Native Image Support: Essential for GraalVM native image compilation
• 📦 Seamless Integration: Works with existing Bazel Java rules
• 🔄 Reproducible Builds: Consistent AOT processing across environments

Installation

Using Bazel Modules (Bzlmod)

Add to your MODULE.bazel:

bazel_dep(name = "rules_spring_aot", version = "0.1.0")

Using WORKSPACE

From the release you wish to use: https://github.com/tharakadesilva/rules_spring_aot/releases copy the WORKSPACE snippet into your WORKSPACE file.

To use a commit rather than a release, you can point at any SHA of the repo.

For example to use commit abc123:

1. Replace url = "https://github.com/tharakadesilva/rules_spring_aot/releases/download/v0.1.0/rules_spring_aot-v0.1.0.tar.gz" with a GitHub-provided source archive like url = "https://github.com/tharakadesilva/rules_spring_aot/archive/abc123.tar.gz"
2. Replace strip_prefix = "rules_spring_aot-0.1.0" with strip_prefix = "rules_spring_aot-abc123"
3. Update the sha256. The easiest way to do this is to comment out the line, then Bazel will print a message with the correct value.

Quick Start

1. Basic Spring Boot Application with AOT

load("@rules_spring_aot//spring_aot:defs.bzl", "spring_aot_library")
load("@rules_java//java:defs.bzl", "java_library", "java_binary")

# Define your Spring Boot application
java_library(
    name = "my-app-lib",
    srcs = glob(["src/main/java/**/*.java"]),
    runtime_deps = [
        "@maven//:org_springframework_boot_spring_boot_starter_web",
    ],
    deps = [
        # ... other dependencies
    ],
)

# Apply AOT processing
# Creates a java_library containing all AOT-generated classes and resources
spring_aot_library(
    name = "my-app-aot",
    target = ":my-app-lib",
    main_class = "com.example.MyApplication",
    group_id = "com.example",
    artifact_id = "my-app",
)

# Create executable JAR
# Produces a standard JAR with improved startup time (faster than regular Spring Boot, slower than native)
java_binary(
    name = "my-app",
    main_class = "com.example.MyApplication",
    runtime_deps = [":my-app-aot"],
    jvm_flags = ["-Dspring.aot.enabled=true"],
)

2. Native Image with GraalVM

See rules_graalvm for setup instructions.

load("@rules_spring_aot//spring_aot:defs.bzl", "spring_aot_library")
load("@rules_graalvm//graalvm:defs.bzl", "native_image")

# ... (previous definitions)

# Build native executable
native_image(
    name = "my-app-native",
    main_class = "com.example.MyApplication",
    native_image_tool = "@graalvm//:native-image",
    deps = [":my-app-aot"],
)

Requirements

• Bazel 8.3 or higher
• Java 17 or higher
• Spring Boot 3.0 or higher (requires AOT support)
  • Note: org.springframework.boot/spring-boot must be present in the target java_library's classpath
• GraalVM (optional, for native image builds)
• Platform: Linux (Ubuntu; Debian needs testing) and macOS only (Windows is not supported)