Merge ~sergiodj/ubuntu-docker-images/+git/loki:examples into ~ubuntu-docker-images/ubuntu-docker-images/+git/loki:2.4-22.04

[Sergio Durigan Junior]

This MP adds the docker-compose and microk8s examples to the Loki ROCK.

There's not much to say here; the docker-compose.yaml should be pretty straightforward, and the microk8s deployment file, albeit a bit more involved, also follows what we've already been doing for our other images.

Tested locally, everything is working as expected.

[Bryce Harrington (bryce)]

Just a code review, didn't test the commands, but no obvious typos or logic issues. LGTM, +1.

review: Approve

[Sergio Durigan Junior (sergiodj)]

Thanks, Bryce. Merged.

diff --git a/examples/README.md b/examples/README.md
new file mode 100644
index 0000000..f36e8a3
--- /dev/null
+++ b/examples/README.md
@@ -0,0 +1,54 @@
+# Running the examples
+
+## docker-compose
+
+Install `docker-compose` from the Ubuntu archive:
+
+```
+$ sudo apt install -y docker-compose
+```
+
+Call `docker-compose` from the examples directory:
+
+```
+$ docker-compose up -d
+```
+
+Access `http://localhost:3100` and Loki will be running in the
+background.  The `docker-compose` configuration file will start a
+`promtail` container as well, which will connect to the `loki`
+service.
+
+To stop these services, run:
+
+```
+$ docker-compose down
+```
+
+# Microk8s
+
+With microk8s running, enable the `dns` add-on:
+
+```
+$ microk8s enable dns
+```
+
+Create a configmap for the configuration files:
+
+```
+$ microk8s kubectl create configmap promtail-config \
+		--from-file=promtail=config/promtail-local-config-k8s.yaml
+```
+
+Apply the `loki-deployment.yml`:
+
+```
+$ microk8s kubectl apply -f loki-deployment.yml
+```
+
+Access `http://localhost:31000` and Loki will be running.  For
+example, you can:
+
+```
+$ curl -s http://localhost:31000/loki/api/v1/label/job/values
+```
diff --git a/examples/config/promtail-local-config-k8s.yaml b/examples/config/promtail-local-config-k8s.yaml
new file mode 100644
index 0000000..20dec1b
--- /dev/null
+++ b/examples/config/promtail-local-config-k8s.yaml
@@ -0,0 +1,18 @@
+server:
+  http_listen_port: 9080
+  grpc_listen_port: 0
+
+positions:
+  filename: /tmp/positions.yaml
+
+clients:
+  - url: http://loki-service:3100/loki/api/v1/push
+
+scrape_configs:
+- job_name: system
+  static_configs:
+  - targets:
+      - localhost
+    labels:
+      job: varlogs
+      __path__: /var/log/*log
diff --git a/examples/config/promtail-local-config.yaml b/examples/config/promtail-local-config.yaml
new file mode 100644
index 0000000..ed06e8c
--- /dev/null
+++ b/examples/config/promtail-local-config.yaml
@@ -0,0 +1,18 @@
+server:
+  http_listen_port: 9080
+  grpc_listen_port: 0
+
+positions:
+  filename: /tmp/positions.yaml
+
+clients:
+  - url: http://loki:3100/loki/api/v1/push
+
+scrape_configs:
+- job_name: system
+  static_configs:
+  - targets:
+      - localhost
+    labels:
+      job: varlogs
+      __path__: /var/log/*log
diff --git a/examples/docker-compose.yml b/examples/docker-compose.yml
new file mode 100644
index 0000000..22401a7
--- /dev/null
+++ b/examples/docker-compose.yml
@@ -0,0 +1,14 @@
+version: '2'
+
+services:
+    loki:
+        image: ubuntu/loki:edge
+        ports:
+            - 3100:3100
+    promtail:
+        image: ubuntu/loki:edge
+        entrypoint: ""
+        command: /usr/bin/promtail -config.file=/etc/loki/promtail-local-config.yaml
+        volumes:
+            - ./config/promtail-local-config.yaml:/etc/loki/promtail-local-config.yaml
+        depends_on: [ loki ]
diff --git a/examples/loki-deployment.yml b/examples/loki-deployment.yml
new file mode 100644
index 0000000..cb14b05
--- /dev/null
+++ b/examples/loki-deployment.yml
@@ -0,0 +1,77 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: loki-service
+spec:
+  type: NodePort
+  selector:
+    app: loki
+  ports:
+  - protocol: TCP
+    port: 3100
+    targetPort: 3100
+    nodePort: 31000
+    name: loki
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: loki-deployment
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: loki
+  template:
+    metadata:
+      labels:
+        app: loki
+    spec:
+      containers:
+      - name: loki
+        image: ubuntu/loki:edge
+        ports:
+        - containerPort: 3100
+          name: loki
+          protocol: TCP
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: promtail-service
+spec:
+  selector:
+    app: promtail
+  ports:
+    - port: 9080
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: promtail-deployment
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: promtail
+  template:
+    metadata:
+      labels:
+        app: promtail
+    spec:
+      containers:
+      - name: promtail
+        image: ubuntu/loki:edge
+        command: [ "/usr/bin/promtail" ]
+        args: [ "-config.file=/etc/loki/promtail-local-config-k8s.yaml" ]
+        volumeMounts:
+        - name: promtail-config-volume
+          mountPath: /etc/loki/promtail-local-config-k8s.yaml
+          subPath: promtail-local-config-k8s.yaml
+      volumes:
+        - name: promtail-config-volume
+          configMap:
+            name: promtail-config
+            items:
+            - key: promtail
+              path: promtail-local-config-k8s.yaml