Minor changes to Stackdriver example (#289)

* Minor changes to Stackdriver example

* A Promethues example that mirrors the existing Stackdriver example

* Fixed typo

* README for examples

* Corrected port reference (should be 9464)

* Remove vestigial Stackdriver dependency

* Fixed installation instructions. Added Dockerfiles and instructions.

* Replaced jshint with gts

* Migrated Dockerfiles node:8 --> node:10

* Added Debugging info to README; Stackdriver example now uses env vars

* Remove redundant (switched to gts) jshint inline config

examples/stats/exporter/Dockerfile.prometheus

@@ -0,0 +1,13 @@
+FROM node:10
+
+WORKDIR /usr/src/app
+
+COPY package.json .
+RUN npm install
+
+COPY prometheus.js .
+COPY test.txt .
+
+EXPOSE 9464
+
+ENTRYPOINT ["node","prometheus.js"]

examples/stats/exporter/Dockerfile.stackdriver

@@ -0,0 +1,11 @@
+FROM node:10
+
+WORKDIR /usr/src/app
+
+COPY package.json .
+RUN npm install
+
+COPY stackdriver.js .
+COPY test.txt .
+
+ENTRYPOINT ["node","stackdriver.js"]

examples/stats/exporter/README.md

@@ -0,0 +1,188 @@
+# Examples
+
+You will need to:
+
+1. Clone this repo and install dependent packages
+
+```bash
+WORK=[[YOUR-WORKING-DIRECTORY]]
+cd ${WORK}
+
+git clone https://github.com/census-instrumentation/opencensus-node
+
+cd opencensus-node
+npm install
+```
+
+## Stackdriver
+
+The sample uses Application Default Credentials to authenticate with the Stackdriver service.
+
+See https://developers.google.com/identity/protocols/application-default-credentials
+
+You will need to:
+
+1. Create a Google Cloud Platform project and Enable Billing
+1. Create a Stackdriver workspace
+1. Create a service account and ensure it is permitted to write Stackdriver metrics
+1. Optional: Visual Studio Code debugging
+1. Run the sample
+1. Observe the metrics
+
+### Create Google Cloud Platform project and Enable Billing
+
+```bash
+PROJECT=[[YOUR-PROJECT]]
+BILLING=[[YOUR-BILLING]]
+
+gcloud projects create ${PROJECT}
+
+gcloud beta billing projects link ${PROJECT} \
+--billing-account=${BILLING}
+```
+### Create Stackdriver workspace
+
+```
+google-chrome console.cloud.google.com/monitoring/?project=${PROJECT}
+```
+
+### Create Service Account with correct permissions
+
+```bash
+ACCOUNT=[[YOUR-SERVICE-ACCOUNT]]
+ADDRESS=${ACCOUNT}@${PROJECT}.iam.gserviceaccount.com
+
+WORK=[[YOUR-WORKING-DIRECTORY]]
+FILE="${WORK}/${ACCOUNT}.key.json"
+
+gcloud iam service-accounts create ${ACCOUNT} \
+--display-name=${ACCOUNT} \
+--project=${PROJECT}
+
+gcloud projects add-iam-policy-binding ${PROJECT} \
+--member=serviceAccount:${ADDRESS} \
+--role=roles/monitoring.metricWriter
+
+gcloud iam service-accounts keys create ${FILE} \
+--iam-account=${ACCOUNT}@${PROJECT}.iam.gserviceaccount.com \
+--project=${PROJECT}
+```
+
+### Optional: Visual Studio Code Debugging 
+
+If you wish to debug the code in Visual Studio Code, you will need to edit the `launch.json` file:
+
+```json
+{
+    "version": "0.2.0",
+    "configurations": [
+        ...,
+        {
+            "type": "node",
+            "request": "launch",
+            "name": "Stackdriver",
+            "program": "${workspaceFolder}/examples/stats/exporter/stackdriver.js",
+            "env":{
+                "GOOGLE_APPLICATION_CREDENTIALS":"[[Replace with the value of ${WORK}/${ACCOUNT}.key.json]]",
+                "GOOGLE_PROJECT_ID": "[[Replace with the value of ${PROJECT}]]"
+            }
+        },
+      ...,
+    ]
+}
+```
+
+### Run it
+
+```bash
+GOOGLE_APPLICATION_CREDENTIALS=${FILE} node ./stackdriver.js
+```
+
+Alternatively, if you'd prefer to use Docker:
+
+```bash
+IMAGE=[[YOUR-STACKDRIVER-IMAGE]]
+TAG=[[YOUR-TAG]]
+
+docker build \
+  --tag=${IMAGE}:${TAG} \
+  --file=./Dockerfile.stackdriver \
+  .
+
+docker run \
+  --interactive \
+  --tty \
+  --mount=type=bind,src=${WORK}/${ACCOUNT}.key.json,dst=/keys/${ACCOUNT}.key.json \
+  --env=GOOGLE_APPLICATION_CREDENTIALS=/keys/${ACCOUNT}.key.json \
+  --env=GOOGLE_PROJECT_ID=${PROJECT} \
+  ${IMAGE}:${TAG}
+```
+
+### Observe it
+
+Look for the metrics (prefixed `repl/`) in metrics explorer:
+
+```bash
+google-chrome console.cloud.google.com/monitoring/?project=${PROJECT}
+```
+
+
+## Prometheus
+
+The Prometheus sample is standalone and runs without any additional setup.
+
+If you'd like to see the metrics consumed by a Prometheus server, you will need to configure this.
+
+### Optional: Visual Studio Code Debugging 
+
+If you wish to debug the code in Visual Studio Code, you will need to edit the `launch.json` file:
+
+```json
+{
+    "version": "0.2.0",
+    "configurations": [
+        ...,
+        {
+            "type": "node",
+            "request": "launch",
+            "name": "Prometheus",
+            "program": "${workspaceFolder}/examples/stats/exporter/prometheus.js"
+        },
+      ...,
+    ]
+}
+```
+
+
+### Run it
+
+```bash
+node ./prometheus.js
+```
+
+Alternatively, if you'd prefer to use Docker:
+
+```bash
+IMAGE=[[YOUR-PROMETHEUS-IMAGE]]
+TAG=[[YOUR-TAG]]
+
+docker build \
+  --tag=${IMAGE}:${TAG} \
+  --file=./Dockerfile.prometheus \
+  .
+
+docker run \
+  --interactive \
+  --tty \
+  --publish=9464:9464 \
+  ${IMAGE}:${TAG}
+```
+
+### Observer it
+
+You can observe the Prometheus Metrics Exporter that is created by the sample:
+```bash
+google-chrome http://localhost:9464/metrics
+```
+
+

examples/stats/exporter/package.json

@@ -0,0 +1,30 @@
+{
+  "name": "@opencensus/examples",
+  "version": "0.0.8",
+  "description": "OpenCensus is a toolkit for collecting application performance and behavior data.",
+  "repository": "census-instrumentation/opencensus-node",
+  "scripts": {},
+  "keywords": [
+    "opencensus",
+    "nodejs",
+    "tracing",
+    "profiling"
+  ],
+  "author": "Google Inc.",
+  "license": "Apache-2.0",
+  "engines": {
+    "node": ">=6.0"
+  },
+  "files": [],
+  "publishConfig": {
+    "access": "public"
+  },
+  "devDependencies": {
+    "gts": "^0.9.0"
+  },
+  "dependencies": {
+    "@opencensus/core": "^0.0.8",
+    "@opencensus/exporter-prometheus": "^0.0.8",
+    "@opencensus/exporter-stackdriver": "^0.0.8"
+  }
+}