[FEATURE] Support configurable server url for a2a

[jmunozro]

📋 Prerequisites

• I have searched the existing issues to avoid creating a duplicate
• By submitting this issue, you agree to follow our Code of Conduct

📝 Feature Summary

Support configurable server url for a2a

❓ Problem Statement / Motivation

Currently the a2a url is always 127.0.0.1:

❯ curl localhost:8083/api/a2a/kagent/k8s-a2a-agent/.well-known/agent.json -ks| jq .
{
  "name": "k8s_a2a_agent",
  "description": "An example A2A agent that knows how to use Kubernetes tools.",
  "url": "http://127.0.0.1:8083/api/a2a/kagent/k8s-a2a-agent/",
  "version": "",
  "capabilities": {
    "streaming": true,
    "pushNotifications": false,
    "stateTransitionHistory": true
  },
  "defaultInputModes": [
    "text"
  ],
  "defaultOutputModes": [
    "text"
  ],
  "skills": [
    {
      "id": "get-resources-skill",
      "name": "Get Resources",
      "description": "Get resources in the Kubernetes cluster",
      "tags": [
        "k8s",
        "resources"
      ],
      "examples": [
        "Get all resources in the Kubernetes cluster",
        "Get the pods in the default namespace",
        "Get the services in the istio-system namespace",
        "Get the deployments in the istio-system namespace",
        "Get the jobs in the istio-system namespace",
        "Get the cronjobs in the istio-system namespace",
        "Get the statefulsets in the istio-system namespace"
      ],
      "inputModes": [
        "text"
      ],
      "outputModes": [
        "text"
      ]
    }
  ]
}

This is a big limitation to integrate it with external tooling.

💡 Proposed Solution

Provide a way in the controller to provide the serverbase url.
I believe this is possible in the kagent cli with KAGENT_URL, but not for a2a

🔄 Alternatives Considered

No response

🎯 Affected Service(s)

None

📚 Additional Context

No response

🙋 Are you willing to contribute?

• I am willing to submit a PR for this feature

[onematchfox]

I think this should already be possible using the flag a2a-base-url - although this isn't currently exposed in the Helm chart at the moment.

See also use of this variable here.

[jmunozro]

Can you give an example of how we can do this today? If it is not exposed in the CRD, I don't see how it can be used.

[onematchfox]

localhost:8083/api/a2a/... is the URL to a dynamically registered handler exposed by the KAgent controller which proxies the request to the agent. So, if you set the flag -a2a-base-url example.com when running the controller then AFAIK the agent card should be updated to reflect that base URL. You can see how args are set when installing via Helm here.

[onematchfox]

FYI: If you're deploying via main then you can now set the A2A Base URL via Helm values:

controller:
  env:
    - name: A2A_BASE_URL
      value: https://kagent.foo.com

This will reflect on the URL across all agent cards.