GraalVM native with eclair dependencies

Example project showing the usage of a simple akka http server with json serialization, compiled with GraalVM native-image. The goal of the project is to use all of eclair's dependencies to prepare moving to the graal platform.

Pre-requisites

Maven 3.6.x
GraalVM version 19.2.0
native-image from $GRAAL_HOME/bin in PATH

Suggested environment variables:

export GRAAL_HOME=/path/to/your/graal/installation/graalvm-ce-19.2.0
export PATH=$PATH:$GRAAL_HOME/bin

Install native-image:

gu install native-image

This project needs bitcoin-lib v0.17-SNAPSHOT which is not currently published, in order to build it you first need to build its dependency secp256k1-jni. Once you successfully installed the artifact in your local maven repo then you can build the correct version of bitcoin-lib, this is a prerequisite for building this project.

Compiling

JAVA_HOME=$GRAAL_HOME mvn clean package

It might take a few minutes to compile.

Running

# Linux:
target/graal-akka-maven -Djava.library.path=$JAVA_HOME/lib

Because the project is compiled with Java Crypto enabled for the native image (to support HTTPS) java.library.path system property must be set at runtime to point to a directory where the dynamic library for the SunEC provider is located.

What works

Akka-actor 2.5
Akka-http 10.1.8 (see /json endpoint for a demo)
Logging
Typesafe config
Json4s-jackson (no reflection though) (see /json endpoint for a demo)
JHeaps (see /jheaps endpoint for a demo)
Scodec (see /scodec endpoint for a demo)
Apache commons codec (see /commons endpoint for a demo)
SQLite 3.27.2.1 with JNI (see /query?name=Hal endpoint for a demo)
bitcoin-lib with JNI (see /bitcoinlib endpoint for a demo)
Guava 24-android (see /hostandport endpoint)

What doesn't work

Sttp with OkHttpBackend doesn't work, there is an issue oracle/graal#1521 where users claim that using a particular version of OkHttp does work, however sttp is built against a different version.

Missing libraries from eclair-core

JeroMQ

How it works

Most of the graal-specific configuration for native-image in the graal-config folder.The akka-specific configuration is provided by akka-graal-config repository which publishes a set of jar artifacts that contain the necessary configuration resources for native-image to compile Akka modules. Just having these jars in the classpath is enough for native-image to pick up this configuration. See this blog post for more details on how that mechanism works.

Reflection configuration

See SubstrateVM docs for details.

Configuration for Akka itself is provided by akka-graal-config dependencies. This repo contains only reflection configuration to get java.util.logging working.

Note however that reflective access to context and self fields must be configured for every actor that is monitored with context.watch (observed empirically). Otherwise you'll get an error from Akka's machinery.

HTTPS

Passing the --enable-url-protocols=https option to native-image enables JCE features. This configuration option is enabled by configuration from graal-akka-http dependency.

Affinity Pool

akka.dispatch.affinity.AffinityPool is using MethodHandles which causes errors like this one during native image build:

Error: com.oracle.graal.pointsto.constraints.UnsupportedFeatureException: Invoke with MethodHandle argument could not be reduced to at most a single call: java.lang.invoke.MethodHandle.bindTo(Object)

The workaround is to initialize affected classes (and we actually do this for the whole classpath) at build time using the --initalize-at-build-time option.

Bitcoin-lib

bitcoin-lib is a library for bitcoin primitives by ACINQ, it uses the native libsecp256k1 to perform EC operations and that is wrapped in a JNI layer. To use bitcoin-lib with graal's native-image you need to build a particular version of the JNI (the standard ones don't work because of the static initialization), follow the instructions here to build secp256k1-jni. Only after you published locally secp256k1-jni you can build the required version of bitcoin-lib from here.

Lightbend Config

Static initializers of com.typesafe.config.impl.ConfigImpl$EnvVariablesHolder and com.typesafe.config.impl.ConfigImpl$SystemPropertiesHolder need to be run at runtime using the --initialize-at-run-time option. Otherwise the environment from image build time will be baked in to the configuration.

Logging

It is currently not easy to get Logback working because of its Groovy dependencies and incomplete classpath problems with native-image so java.util.logging is used instead.

araspitzu/maven-graal