document running prometheus server in kubernetes

README.md

@@ -76,6 +76,10 @@ shellyctl prometheus --config=config.yaml
 ```
 
 ### Prometheus Server
+The `prometheus` sub-command facilitates running a [Prometheus](https://prometheus.io/) compatible metrics server.
+
+See [contrib/k8s](contrib/k8s) for instructions on running the prometheus server within a Kubernetes cluster.
+
 ```
 Host a prometheus metrics exporter for shelly devices
 

contrib/k8s/README.md

@@ -0,0 +1,53 @@
+# Example Kubernetes Manifests
+
+This folder provides two example Kubernetes manifests:
+* [shellyctl-prom-hostNetwork.yaml](shellyctl-prom-hostNetwork.yaml) - Configures a prometheus server with mDNS search enabled on all interfaces. To support mDNS discovery this pod MUST run with `hostNetwork: true` which enables additional network privileges. To avoid port-conficts during pod replacement, the server is run as a StatefulSet w/ 1 replica.
+* [shellyctl-prom.yaml](shellyctl-prom.yaml) - Configures a prometheus server running within pod networking. This leverages a traditional Deployment model. Because no mDNS/BLEdiscovery is possible you MUST specify hosts in the config file or configure and MQTT server.
+
+## Updating configuration
+Both variants leverage a config-map for configuring shellyctl flags. Shellyctl does NOT support live config reloading so you must restar or replace the pod to reload configuration.
+
+```
+# edit the config file.
+kubectl edit -n shellyctl configmap shellyctl-prom
+
+# replace shellyctl pods to reload configuration
+kubectl delete pod -n shellyctl --all
+```
+
+## Service Discovery
+These examples use the `prometheus.io/scrape` and `prometheus.io/port` anotations for service discovery. Your prometheus service discovery may be configured differently. See:
+* [Prometheus Service Discovery Configuration](https://prometheus.io/docs/prometheus/latest/configuration/configuration/)
+* [PodMonitor/ServiceMonitor in Prometheus Operator](https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/user-guides/getting-started.md#deploying-a-sample-application)
+* [Victoria Metrics Agent](https://docs.victoriametrics.com/vmagent/)
+
+
+## shellyctl-prom-hostNetwork.yaml
+```
+# Create a namespace, shellyctl.
+kubectl create namespace shellyctl
+
+# Optionally add a password for authenticating with devices. This step may be skipped if you do not use auth.
+kubectl create secret -n shellyctl generic shellyctl-auth --from-literal=SHELLYCTL_AUTH=password
+
+# Apply the manifest.
+kubectl apply -f https://raw.githubusercontent.com/jcodybaker/shellyctl/main/contrib/k8s/shellyctl-prom-hostNetwork.yaml
+```
+
+## shellyctl-prom.yaml
+```
+# Create a namespace, shellyctl.
+kubectl create namespace shellyctl
+
+# Optionally add a password for authenticating with devices. This step may be skipped if you do not use auth.
+kubectl create secret -n shellyctl generic shellyctl-auth --from-literal=SHELLYCTL_AUTH=password
+
+# Download the manifest for local editing.
+curl -LfO https://raw.githubusercontent.com/jcodybaker/shellyctl/main/contrib/k8s/shellyctl-prom.yaml
+
+# Edit the `host` list in configmap.
+editor shellyctl-prom.yaml
+
+# Apply the manifest.
+kubectl apply -f shellyctl-prom.yaml
+```

contrib/k8s/shellyctl-prom.yaml

@@ -0,0 +1,86 @@
+---
+apiVersion: v1
+kind: Namespace
+metadata:
+  labels:
+    kubernetes.io/metadata.name: shellyctl
+  name: shellyctl
+
+---
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: shellyctl-prom
+  namespace: shellyctl
+data:
+  shellyctl-prom.yaml: |
+    bind-port: 9090
+    log-level: debug
+    host:
+    # Example host config with password.
+    - http://admin:[email protected]
+    - http://127.0.0.1
+
+---  
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  labels:
+    app: shellyctl-prom
+  name: shellyctl-prom
+  namespace: shellyctl
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: shellyctl-prom
+  template:
+    metadata:
+      labels:
+        app: shellyctl-prom
+    spec:
+      containers:
+      - command:
+        - /bin/shellyctl
+        - prometheus
+        env:
+        - name: SHELLYCTL_CONFIG
+          value: /run/shellyctl/shellyctl-prom.yaml
+        image: ghcr.io/jcodybaker/shellyctl:latest
+        imagePullPolicy: Always
+        name: shellyctl
+        ports:
+        - containerPort: 9090
+          protocol: TCP
+        volumeMounts:
+        - mountPath: /run/shellyctl
+          name: config
+      dnsPolicy: ClusterFirst
+      restartPolicy: Always
+      terminationGracePeriodSeconds: 30
+      volumes:
+      - configMap:
+          defaultMode: 420
+          name: shellyctl-prom
+        name: config
+
+---
+apiVersion: v1
+kind: Service
+metadata:
+  labels:
+    app: shellyctl-prom
+  annotations:
+    prometheus.io/port: "9090"
+    prometheus.io/scrape: "true"
+  name: shellyctl-prom
+  namespace: shellyctl
+spec:
+  ports:
+  - name: 9090-9090
+    port: 9090
+    protocol: TCP
+    targetPort: 9090
+  selector:
+    app: shellyctl-prom
+  type: ClusterIP

pkg/discovery/discovery.go

@@ -80,7 +80,7 @@ func (d *Discoverer) AddDeviceByAddress(ctx context.Context, addr string, opts .
 	default:
 		return nil, fmt.Errorf("unsupported URI scheme %q", u.Scheme)
 	}
-	if u.Path == "" {
+	if u.Path == "" || u.Path == "/" {
 		u.Path = "/rpc"
 	}
 	if u.Path != "/rpc" {