Add Hints and example for Data Neo4j.

[michael-simons]

This PR provides Neo4jRepositoriesHints and Neo4jReactiveRepositoriesHints, triggered by the appropriate auto configuration classes in the latest Spring Boot 2.4.
The hints have been added to RepositoriesHints.

In addition, data-neo4j as an examples has been added. It's basically a copy of the data-mongo sample, with the same domain and the same queries, but for Neo4j.

For a successful run of build.sh, a locally running Neo4j instance is required. The easiest way to get one is

docker run --publish=7474:7474 --publish=7687:7687 -e 'NEO4J_AUTH=neo4j/secret' neo4j:4.1

Please feel free to adapt as necessary.

cc @christophstrobl @meistermeier

[sdeleuze]

Thanks for this contribution @michael-simons. We currently can't use Docker on Docker, so we would need to install Neo4j on our spring-graalvm-native Docker image which will be not straightforward because Neo4j requires requires Java 11+. Since it will require some work on that side I move it to 0.8.2.

[michael-simons]

I think using neo4j:3.5 (requiring JDK 8) should work equally well. I need to add in some config for the connection to work, but that's easily doable.

How are you running MongoDB or elastic? Did you install those on the base image? I cannot imagine you're running their products natively… If so, we would like to have your help making Neo4j native runnable, too :D

[michael-simons]

So, I switched the compose script to Neo4j 3.5 and added a hint to the pom about the need for all security services when people might want to use an encrypted connection. Please let me know if this works for you.

[sdeleuze]

Nice, we can maybe try to make it runnable for 0.8.1 then.

Do you want to try to add support yourself based on what we did for elasticsearch in fe0e651 and https://repo.spring.io/milestone/org/springframework/experimental/spring-graalvm-native-docs/0.8.0/spring-graalvm-native-docs-0.8.0.zip!/reference/index.html#_using_container_based_build_environment ?

[michael-simons]

Hi, I tried but I failed miserably. Our deb package is complaining about openjdk not installed (and also about package daemon). The later is fixable of course, but it seems not reasonable to replace the jdk.

I started the CI container with docker run -it spring-graalvm-native-dev:20.2-dev-java8 /bin/bash to run my experiments.

When I fix the daemon package (with apt-get install daemon), and than do the following:

curl -LO https://dist.neo4j.org/deb/neo4j_3.5.21_all.deb \
 && dpkg  --force-all -i neo4j_3.5.21_all.deb

In the container, I end up with

Setting up neo4j (1:3.5.21) ...
invoke-rc.d: could not determine current runlevel
invoke-rc.d: policy-rc.d denied execution of start.

Here are our instructions

https://neo4j.com/docs/operations-manual/3.5/installation/linux/debian/

The dl link to the deb is above, tarball would be https://neo4j.com/artifact.php?name=neo4j-community-3.5.22-unix.tar.gz

If you can help me getting the service installed, I can add the missing config bits.

[michael-simons]

I managed to add a running Neo4j 3.5 to the container (also removed the tons of elastic search stack traces), but I cannot manage to get anything build in either the dev or master image. However, mongo or elastic fail as well. I guess this is unrelated.

[sdeleuze]

Ok thanks I will have a deeper look.

[sdeleuze]

I will take care of merging this PR.

[sdeleuze]

Merged with a remaining issue (#300) which is maybe a regression on our side. Thanks a lot @michael-simons, great work.