How to get List of APIGroups using client java api , expecting similar output as fabric8 client

[swagata-sahoo]

Describe the bug
We are trying to get the list of APIGROUPS using client java but we are not able to achieve it . Earlier we are using fabric8 client java ,with using this we were able to fetch the list of APIGROUPS.

We have tried the solution provided as part of #4003 .
We are getting below output when we have used it .

       ApiClient client = Configuration.getDefaultApiClient();
        Configuration.setDefaultApiClient(client);
        Discovery discovery = new Discovery(client);
        V1APIGroupList list = discovery.groupDiscovery("/apis");

Output of list of API group :

output_discovery_APIgrouplist.txt

But with fabric8 we are getting below output

output_fabric8_APIgrouplist.txt

We are expecting similar output with java client api as well . Can you please check and help on this .

Client Version
21.0.1

Kubernetes Version
v1.30.2

Java Version
Java 17

Expected behavior
We are trying to fetch the list of APIGROUPS using client java api
KubeConfig
If applicable, add a KubeConfig file with secrets redacted.

Server (please complete the following information):

• OS: [e.g. Linux]
• Environment [e.g. container]
• Cloud [e.g. Azure]

Additional context
Add any other context about the problem here.

[yue9944882]

it looks like the output from these two output files are exactly the same. they just have different format. am i missing something?

[Storm-Dev6]

Hi @swagata-sahoo,

Thanks for sharing your code and details!

From your description, it seems you want the Java client output to be similar to fabric8’s APIGroup list.

The official Kubernetes Java client (io.kubernetes:client-java) provides a Discovery API but sometimes it returns a different structure or less info compared to fabric8 because fabric8 does some additional processing or formatting.

A few suggestions that might help you get closer output:

1 - After getting V1APIGroupList list = discovery.groupDiscovery("/apis");, try iterating over list.getGroups() and manually extract the details you want (like preferredVersion, versions, name, etc.) and format them similarly to fabric8 output.

2 - Confirm that you are using the latest client version (looks like 21.0.1 is recent).

3 - If the official client is missing some info, fabric8 client is open source, so you might check their source code for how they fetch and format the API groups and implement a similar logic.

Here is a simple example snippet for iterating groups:

V1APIGroupList list = discovery.groupDiscovery("/apis");
for (V1APIGroup group : list.getGroups()) {
System.out.println("Name: " + group.getName());
System.out.println("Preferred Version: " + group.getPreferredVersion().getVersion());
System.out.println("Versions:");
for (V1GroupVersionForDiscovery version : group.getVersions()) {
System.out.println(" - " + version.getVersion());
}
}

This way you can build the output you need.

If you want, I can help you with a more detailed example.