I have a similar issue, reported it on the forums a few days ago, https://community.grafana.com/t/trying-to-connect-selfhosted-grafana-to-cloud-oncall/129985

The difference in my case is that I set the Oncall Backend URL in our self-hosted Grafana to point to our self-hosted Oncall-engine and it successfully connects to it, but the token for Grafana Cloud doesn't work even though it works with curl.

We are still running into this error. Can anyone take a look, please?

Recently we made some changes to the way Grafana OnCall is initialized. Use 1.9.22, there were quite a few changes along the way from 1.9.0-1.9.22 to get things working.

• If you are running Grafana 11 and newer you must have externalServiceAccounts feature toggle enabled.
  This has already been enabled in the docker compose files and helm charts in the oncall repo.
• Plugin settings must be provided to the plugin using an API call if you are installing for the first time (Note: credentials and hostnames need to be adjusted for your configuration, stackId and orgId are expected to be the listed constants in a self-hosted configuration)

curl -X POST 'http://admin:admin@localhost:3000/api/plugins/grafana-oncall-app/settings' -H "Content-Type: application/json" -d '{"enabled":true, "jsonData":{"stackId":5, "orgId":100, "onCallApiUrl":"http://engine:8080/", "grafanaUrl":"http://grafana:3000/"}}'

• Once settings are configured use this API call to install:

curl -X POST 'http://admin:admin@localhost:3000/api/plugins/grafana-oncall-app/resources/plugin/install'

Grafana OnCall should now be ready to use.
For additional troubleshooting see here

Recently we made some changes to the way Grafana OnCall is initialized. Use 1.9.22, there were quite a few changes along the way from 1.9.0-1.9.22 to get things working.

• If you are running Grafana 11 and newer you must have externalServiceAccounts feature toggle enabled.
  This has already been enabled in the docker compose files and helm charts in the oncall repo.
• Plugin settings must be provided to the plugin using an API call if you are installing for the first time (Note: credentials and hostnames need to be adjusted for your configuration, stackId and orgId are expected to be the listed constants in a self-hosted configuration)

curl -X POST 'http://admin:admin@localhost:3000/api/plugins/grafana-oncall-app/settings' -H "Content-Type: application/json" -d '{"enabled":true, "jsonData":{"stackId":5, "orgId":100, "onCallApiUrl":"http://engine:8080/", "grafanaUrl":"http://grafana:3000/"}}'

• Once settings are configured use this API call to install:

curl -X POST 'http://admin:admin@localhost:3000/api/plugins/grafana-oncall-app/resources/plugin/install'

Grafana OnCall should now be ready to use. For additional troubleshooting see here

@mdyerynck This resolves the issue I was previously facing, but now I’m encountering a new challenge. Here’s the error I get in the UI:

And this is what the API returns:

curl -X GET 'http://admin:admin@localhost:3000/api/plugins/grafana-oncall-app/resources/plugin/status' | jq .

{
  "pluginConnection": {
    "settings": {
      "ok": true
    },
    "service_account_token": {
      "ok": true
    },
    "grafana_url_from_plugin": {
      "ok": true
    },
    "grafana_url_from_engine": {
      "ok": false,
      "error": "Not validated"
    },
    "oncall_api_url": {
      "ok": false,
      "error": "Not validated"
    },
    "oncall_token": {
      "ok": false,
      "error": "Unauthorized/Forbidden while accessing OnCall engine: /oncall/api/internal/v1/plugin/v2/status, status code: 403, check token"
    }
  },
  "license": "",
  "version": "",
  "currently_undergoing_maintenance_message": "",
  "api_url": ""
}

I’ve tried setting the ONCALL_API_TOKEN as both an environment variable when starting my Grafana instance and passing it in via the API call, like this:

curl -X POST \
'http://admin:admin@localhost:3000/api/plugins/grafana-oncall-app/settings' \
-H "Content-Type: application/json" \
-d '{
  "enabled": true,
  "jsonData": {
    "stackId": 5,
    "orgId": 100,
    "onCallApiUrl": "<ONCALL API URL>",
    "onCallApiToken": "<ONCALL API TOKEN>",
    "grafanaUrl": "http://localhost:3000/"
  }
}'

Looking through the code in the repo (https://github.com/grafana/oncall), it seems ONCALL_API_TOKEN is the token causing the issue, as mentioned here: https://github.com/grafana/oncall/tree/dev/tools/migrators#configuration

Apparently, you can't connect a plugin in OSS directly to a our cloud instance.
OSS installations are expected to run their own backend services