proguard-spring-boot-example

Proguard Obfuscate Spring Boot Maven Plugin Example

For big spring boot projects we can't obfuscate all files because for example may be will break spring autowiring (by default spring autowiring search classes by variable name) and other blocks. So we must check every obfuscation rules by running .jar file.

Most of the common rules specify in the pom.xml.

Decompiling files by Intellij

We must unzip .jar and put package files in the project/target directory. Then we can open target directory in Intellij project-structure window and open class. This will be real decompiled class.

Before use

First you must change the setting <java.version>11</java.version> in the pom.xml to match your JDK version, for example:

• for JDK 9 change to <java.version>9</java.version>
• for JDK 14 change to <java.version>14</java.version>

After building

After building you can run spring.boot.jar in the target directory, for example:

java -jar spring.boot.jar

Supporting JDK

Currently supported JDK 9, JDK 11 and JDK 14 (maybe also JDK 9, JDK 10 and JDK 13 - I've not tested them)!

JDK after 1.8 (9, 10, 11 etc.) now using modular structure, so they don't contain files rt.jar and jce.jar.

I remove all libraries from the libs section in pom (empty block ). If your application want them you can add system libraries manually, for example:

<libs>
    <lib>${java.home}/lib/rt.jar</lib>
    <lib>${java.home}/lib/jce.jar</lib>
</libs>

For JDK 11 you can try to add all modules from /jmods directory to the libs section in maven pom.

How it works

Obfuscation step must go before packaging .jar so in pom file you can see right order of steps.

We use proguard-maven-plugin. In the configuration, you can pass any options from the original proguard project, but some options may cause failure so recheck any changes. See proguard documentation for all available options and descriptions.

Run JDKs support tests

To run tests from the root directory run command:

docker-compose -f src/test/docker/docker-compose.yml up

After all containers startup successfully we can stop all by command:

docker-compose -f src/test/docker/docker-compose.yml down

Troubleshooting

• If application can't start try remove some classes/packages from obfuscation (option -keep)
• We use option -dontoptimize, but you can try to use optimization but recheck required after every changes
• If maven build failed check your JDK version (currently supports only JDK 9, JDK 11 and JDK 14). See also error output, maybe you compile under JDK 11 and not removed libraries from the libs block so proguard can't find rt.jar and others.
• Some options from the proguard project may not work properly, recheck any new option

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