Implement auto detection

[leszko]

Note that:

• We will need to release with the com.hazelcast:hazelcast:4.1-SNAPSHOT dependency
• This change is 100% backward-compatible (new released hazelcast-kubernetes can be used with older hazelcast versions)
• Apart from auto-detection, the logs are improved

---

After this change, IMO the newbie experience is great.

1. Start Hazelcast on Kubernetes

$ kubectl run hazelcast --image=leszko/hazelcast
$ kubectl logs hazelcast
...
WARNING: Kubernetes API access is forbidden! Starting standalone. To use Hazelcast Kubernetes discovery configure the required RBAC. For 'default' service account in 'default' namespace execute: `kubectl apply -f https://raw.githubusercontent.com/hazelcast/hazelcast-kubernetes/master/rbac.yaml`
Jul 23, 2020 2:05:32 PM com.hazelcast.internal.cluster.ClusterService
INFO: [10.8.1.4]:5701 [dev] [4.1-SNAPSHOT]

Members {size:1, ver:1} [
        Member [10.8.1.4]:5701 - 44a54bd1-34ca-4f8c-93fe-d1ce594eacac this
]

Jul 23, 2020 2:05:32 PM com.hazelcast.core.LifecycleService
INFO: [10.8.1.4]:5701 [dev] [4.1-SNAPSHOT] [10.8.1.4]:5701 is STARTED

2. Execute the recommended command.

$ kubectl apply -f https://raw.githubusercontent.com/hazelcast/hazelcast-kubernetes/master/rbac.yaml

3. Restart Hazelcast and create two instances

$ kubectl delete pod/hazelcast
$ kubectl run hazelcast --image=leszko/hazelcast
$ kubectl run hazelcast-2 --image=leszko/hazelcast
$ kubectl logs hazelcast
...
Members {size:2, ver:2} [
        Member [10.8.1.5]:5701 - 6df84047-4510-460a-ba27-ff75378d217a
        Member [10.8.2.4]:5701 - eb55802e-8358-4931-af88-bac1eaf3819f this
]

No configuration needed!

[pivovarit]

Use Files.isRegularFile(path) instead. Otherwise, you'd need to check if the file is not a directory as well.

Apparently, it's faster as well 🤷‍♀️

[leszko]

Isn't it actually slower? https://rules.sonarsource.com/java/tag/performance/RSPEC-3725

FYI: This will never be a directory, so not a big deal with that.

[pivovarit]

As I see there used to be a bug on JDK 8 which got fixed later on. However, I don't see any signs that it was backported JDK 8, so I guess we can leave it as is 🤷‍♂️

[leszko]

verify