Events example (#261)

* move existing examples to their own directory

* Add k8s events example

* fix example image path

* fix example image file extension

* Update title to include Google Logging. Specify required IAM role for service account

* Add Prerequisites, use CHANGE_ME in config map.

* use correct screenshot for k8s events

examples/k8s/events/USAGE.md

@@ -0,0 +1,51 @@
+# Kubernetes Events w/ Google Cloud Logging
+
+Stanza can be deployed as a Kubernetes Events collector by leveraging the [k8s_event_input](https://github.com/observIQ/stanza/blob/master/docs/operators/k8s_event_input.md) operator. [Minikube](https://minikube.sigs.k8s.io/docs/start/)
+can be used for this example.
+
+## Architecture
+
+1. Service account with permission to the Kubernetes API server
+2. Config map: Contains the stanza configuration file
+3. Credentials secret: Contains Google Cloud [service account credentials JSON file](https://cloud.google.com/docs/authentication/getting-started)
+4. Persistent volume: Allows the stanza database to persist between restarts and pod evictions
+5. Deployment: A single replica deployment for the agent
+
+## Prerequisites
+
+1. Google Cloud account with Cloud Logging API enabled
+2. Google service account with [roles/logging.logWriter](https://cloud.google.com/logging/docs/access-control)
+3. Kubernetes Cluster with a storageclass capable of providing persistent volumes
+4. Edit `config.yaml` to include:
+  - Your cluster name (this is added as a label)
+  - Your project_id
+
+## Deployment Steps
+
+Create the credentials secret. The file provided in this example should be replaced
+with your service account's credentials.
+```
+kubectl create secret generic stanza-agent-credentials \
+  --from-file=log_credentials.json
+```
+
+Create the Kubernetes Service Account
+```
+kubectl apply -f service_account.yaml
+```
+
+Create the config map
+```
+kubectl apply -f config.yaml
+```
+
+Deploy the agent
+```
+kubectl apply -f deployment.yaml
+```
+
+## Validate
+
+Log into Google Cloud Logging
+
+![Events](./assets/events.png)

examples/k8s/events/config.yaml

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+---
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: stanza-agent
+  namespace: default
+data:
+  config.yaml: |
+    pipeline:
+    - type: kubernetes_events
+      cluster_name: CHANGE_ME
+    - credentials_file: /stanza_home/log_destinations/google_cloud/log_credentials.json
+      project_id: CHANGE_ME
+      type: google_cloud_output

examples/k8s/events/deployment.yaml

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+---
+kind: PersistentVolumeClaim
+apiVersion: v1
+metadata:
+   name: stanza-agent-events-persistent-volume
+   namespace: default
+spec:
+   accessModes:
+      - ReadWriteOnce
+   resources:
+      requests:
+          storage: 1Gi
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: stanza-agent-cluster-events
+  namespace: default
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      name: stanza-agent-cluster-events
+  template:
+    metadata:
+      labels:
+        name: stanza-agent-cluster-events
+    spec:
+      serviceAccountName: stanza-agent
+      containers:
+        - image: observiq/stanza:0.13.16
+          imagePullPolicy: Always
+          name: stanza-agent
+          command:
+            - /stanza_home/stanza
+          args:
+            - --config
+            - /stanza_home/config.yaml
+            - --database
+            - /stanza_home/database/stanza.db
+            - --plugin_dir
+            - /stanza_home/plugins
+          resources:
+            limits:
+              memory: "250Mi"
+              cpu: 250m
+            requests:
+              memory: "250Mi"
+              cpu: 100m
+          volumeMounts:
+            - mountPath: /stanza_home/config.yaml
+              subPath: config.yaml
+              name: stanza-agent
+            - mountPath: /stanza_home/log_destinations/google_cloud/log_credentials.json
+              subPath: log_credentials.json
+              name: stanza-agent-credentials
+            - mountPath: /stanza_home/database
+              name: stanza-agent-events-persistent-volume
+      restartPolicy: Always
+      terminationGracePeriodSeconds: 30
+      volumes:
+        - name: stanza-agent
+          configMap:
+            name: stanza-agent
+        - name: stanza-agent-credentials
+          secret:
+            secretName: stanza-agent-credentials
+        - name: stanza-agent-events-persistent-volume
+          persistentVolumeClaim:
+            claimName: stanza-agent-events-persistent-volume

examples/k8s/events/log_credentials.json

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+{
+  "type": "service_account",
+  "project_id": "",
+  "private_key_id": "",
+  "private_key": "",
+  "client_email": "",
+  "client_id": "",
+  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
+  "token_uri": "https://oauth2.googleapis.com/token",
+  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
+  "client_x509_cert_url": ""
+}

examples/k8s/events/service_account.yaml

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+---
+kind: ServiceAccount
+apiVersion: v1
+metadata:
+  name: stanza-agent
+  namespace: default
+---
+kind: ClusterRole
+apiVersion: rbac.authorization.k8s.io/v1
+metadata:
+  name: stanza-agent
+rules:
+  - apiGroups: ["", "apps", "batch"]
+    resources:
+      - pods
+      - namespaces
+      - replicasets
+      - jobs
+      - events
+    verbs: ["get", "list", "watch"]
+---
+kind: ClusterRoleBinding
+apiVersion: rbac.authorization.k8s.io/v1
+metadata:
+  name: stanza-agent
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: ClusterRole
+  name: stanza-agent
+subjects:
+  - kind: ServiceAccount
+    name: stanza-agent
+    namespace: default