Let's say the argocd cluster list command returns "Cluster has no applications and is not being monitored".

~]$ argocd cluster list --grpc-web
SERVER                                      NAME                VERSION  STATUS      MESSAGE                                                  PROJECT
https://api.dev.openshift.example.com:6443  dev-cluster                  Unknown     Cluster has no applications and is not being monitored.
https://kubernetes.default.svc              in-cluster          1.27     Successful

Likewise the argocd cluster get command can be used to display a little bit more information about the cluster. Notice in this example that applicationsCount is 0 which is why the argocd cluster list command returns "Cluster has no applications" and status is unknown which is why the argocd cluster list command returns "is not being monitored".

~]$ argocd cluster get dev-cluster
config:
  tlsClientConfig:
    caData: LS0tLS1CR.....S0tLQ0K
connectionState:
  attemptedAt: "2024-12-19T02:47:08Z"
  message: Cluster has no applications and is not being monitored.
  status: Unknown
info:
  applicationsCount: 0
  cacheInfo: {}
  connectionState:
    attemptedAt: "2024-12-19T02:47:08Z"
    message: Cluster has no applications and is not being monitored.
    status: Unknown
name: dev-cluster
server: https://api.dev.openshift.example.com:6443

This almost always simply means you have not yet created an application using ArgoCD in the cluster. Let's create an application in the cluster. Check out my article ArgoCD - Create Application using the CLI.

argocd app create demo \
--repo https://github.com/foo/bar.git \
--path my-files \
--dest-namespace my-namespace \
--dest-server https://api.dev.openshift.example.com:6443
--project my-project

Now that an application has been created in the cluster the argocd cluster list command should no longer return "Cluster has no applications and is not being monitored". However, the status is still Unknown (this is probably an indication that something is not properly configured).

~]$ argocd cluster list
SERVER                                      NAME         VERSION  STATUS   MESSAGE  PROJECT
https://api.dev.openshift.example.com:6443  dev-cluster           Unknown
https://kubernetes.default.svc              in-cluster            Unknown

And likewise now the argocd cluster get command has applicationsCount: 1 so we know there was indeed an attempt to create an application on the cluster. In this example, status remains Unknown thus there probably is still some other misconfiguration.

~]$ argocd cluster get dev-cluster
config:
  tlsClientConfig:
    caData: LS0tLS1CR.....S0tLQ0K
connectionState:
  attemptedAt: "2025-01-28T02:17:29Z"
  message: ""
  status: Unknown
info:
  applicationsCount: 1
  cacheInfo: {}
  connectionState:
    attemptedAt: "2025-01-28T02:17:29Z"
    message: ""
    status: Unknown
name: dev-cluster
server: https://api.dev.openshift.example.com:6443

The kubectl (Kubernetes) or oc (OpenShift) logs command on the Kubernetes or OpenShift cluster that ArgoCD is on can be used to see the server pod logs. In this example, all of the logs are at log level INFO meaning there are no obvious errors.

~]# oc logs openshift-gitops-server-7dddf67589-g5nzq --namespace openshift-gitops

time="2025-01-28T02:18:42Z" level=info msg="Loading TLS configuration from secret openshift-gitops/argocd-server-tls"

time="2025-01-28T02:18:42Z" level=info msg="received unary call /version.VersionService/Version" grpc.method=Version grpc.request.claims="{\"exp\":1738115980,\"iat\":1738029580,\"iss\":\"argocd\",\"jti\":\"0a020904-6b25-4729-9999-98467dd6d89d\",\"nbf\":1738029580,\"sub\":\"admin\"}" grpc.request.content= grpc.service=version.VersionService grpc.start_time="2025-01-28T02:18:42Z" span.kind=server system=grpc

time="2025-01-28T02:18:42Z" level=info msg="Loading TLS configuration from secret openshift-gitops/argocd-server-tls"

time="2025-01-28T02:18:42Z" level=info msg="finished unary call with code OK" grpc.code=OK grpc.method=Version grpc.service=version.VersionService grpc.start_time="2025-01-28T02:18:42Z" grpc.time_ms=0.731 span.kind=server system=grpc

time="2025-01-28T02:18:42Z" level=info msg="Loading TLS configuration from secret openshift-gitops/argocd-server-tls"

time="2025-01-28T02:18:42Z" level=info msg="received unary call /cluster.ClusterService/Get" grpc.method=Get grpc.request.claims="{\"exp\":1738115980,\"iat\":1738029580,\"iss\":\"argocd\",\"jti\":\"0a020904-6b25-4729-9999-98467dd6d89d\",\"nbf\":1738029580,\"sub\":\"admin\"}" grpc.request.content="name:\"onprem-dev\" " grpc.service=cluster.ClusterService grpc.start_time="2025-01-28T02:18:42Z" span.kind=server system=grpc

time="2025-01-28T02:18:42Z" level=info msg="Loading TLS configuration from secret openshift-gitops/argocd-server-tls"

time="2025-01-28T02:18:42Z" level=info msg="finished unary call with code OK" grpc.code=OK grpc.method=Get grpc.service=cluster.ClusterService grpc.start_time="2025-01-28T02:18:42Z" grpc.time_ms=0.856 span.kind=server system=grpc