Add agent api example with prometheus and grafana

.gitignore

@@ -1,4 +1,5 @@
 build/
+**/build/
 bin/
 whitesource/
 .vscode/

examples/grafana-metrics/Dockerfile

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+FROM ubuntu:22.04 as install
+LABEL maintainer="NGINX Agent Maintainers <[email protected]>"
+
+WORKDIR /agent
+COPY ./build/nginx-agent.deb /agent/nginx-agent.deb
+COPY ./entrypoint.sh /agent/entrypoint.sh
+COPY ./nginx-agent.conf /agent/nginx-agent.conf
+COPY ./nginx.conf /agent/nginx.conf
+
+RUN set -x \
+    && addgroup --system --gid 101 nginx \
+    && adduser --system --disabled-login --ingroup nginx --no-create-home --home /nonexistent --gecos "nginx user" --shell /bin/false --uid 101 nginx \
+    && apt-get update \
+    && apt-get install --no-install-recommends --no-install-suggests -y \
+                        ca-certificates \
+                        gnupg1 \
+                        lsb-release \
+                        git \
+                        wget \
+                        make \
+                        curl \
+                        vim \
+    && apt-get update \
+    && apt-get install -y build-essential libpcre3 libpcre3-dev zlib1g zlib1g-dev libssl-dev \
+    && wget http://nginx.org/download/nginx-1.23.2.tar.gz \
+    && tar xfz nginx-1.23.2.tar.gz \
+    && cd nginx-1.23.2 \
+    && cp /agent/nginx.conf ./conf/nginx.conf \
+    && ./configure --with-http_stub_status_module \
+    && make \
+    && make install \
+    && apt-get install -y -f /agent/nginx-agent.deb 
+
+# run the nginx and agent
+FROM install as runtime
+
+COPY --from=install /agent/entrypoint.sh /agent/entrypoint.sh
+COPY --from=install /agent/nginx-agent.conf /etc/nginx-agent/nginx-agent.conf
+
+RUN chmod +x /agent/entrypoint.sh
+STOPSIGNAL SIGTERM
+EXPOSE 80 443
+
+ENTRYPOINT ["/agent/entrypoint.sh"]

examples/grafana-metrics/Makefile

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+
+help: ## Show help message
+	@awk 'BEGIN {FS = ":.*##"; printf "\nUsage:\033[36m\033[0m\n"} /^[$$()% 0-9a-zA-Z_-]+:.*?##/ { printf "  \033[36m%-24s\033[0m %s\n", $$1, $$2 } /^##@/ { printf "\n\033[1m%s\033[0m\n", substr($$0, 5) } ' $(MAKEFILE_LIST)
+
+clean: ## Remove docker containers and agent package
+	docker-compose down
+	rm -rf ./build
+
+build: ## Build agent package
+	mkdir ./build
+	cd ../../ && GOWORK=off CGO_ENABLED=0 GOARCH=amd64 GOOS=linux go build -o ./build/nginx-agent
+	cd ../../ && nfpm pkg --config ./scripts/.local-nfpm.yaml --packager deb --target ./examples/grafana-metrics/build/nginx-agent.deb
+
+run: ## Start docker containers
+	docker-compose up --build

examples/grafana-metrics/README.md

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+# Grafana Metrics Example
+This example demonstrates how the NGINX agent can be used to report metrics using prometheus and grafana servers.
+
+## Run Example
+
+```
+make clean build run
+```
+
+## Example of Grafana Dashboard
+
+![Dashboard](grafana-dashboard-example.png)

examples/grafana-metrics/docker-compose.yml

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+version: '3.9'
+
+networks:
+  monitoring:
+    driver: bridge
+
+volumes:
+  prometheus_data: {}
+
+services:
+  agent:
+    build: ./
+    image: nginx/agent-example
+    container_name: agent
+    ports:
+      - 9091:9091
+    networks:
+      - monitoring
+  prometheus:
+    image: prom/prometheus:latest
+    container_name: prometheus
+    restart: unless-stopped
+    volumes:
+      - ./prometheus.yml:/etc/prometheus/prometheus.yml
+      - prometheus_data:/prometheus
+    command:
+      - '--config.file=/etc/prometheus/prometheus.yml'
+      - '--storage.tsdb.path=/prometheus'
+      - '--web.console.libraries=/etc/prometheus/console_libraries'
+      - '--web.console.templates=/etc/prometheus/consoles'
+      - '--web.enable-lifecycle'
+    ports:
+      - 9090:9090
+    networks:
+      - monitoring
+  grafana:
+    image: grafana/grafana-oss:latest
+    volumes:
+      - ./grafana-datasources.yml:/etc/grafana/provisioning/datasources/grafana-datasources.yml
+      - ./grafana-dashboards.yml:/etc/grafana/provisioning/dashboards/grafana-dashboards.yml
+      - ./nginx-agent-dashboard.json:/var/lib/grafana/dashboards/nginx-agent-dashboard.json
+    ports:
+      - 3000:3000
+    networks:
+      - monitoring

examples/grafana-metrics/entrypoint.sh

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+#!/bin/bash
+
+set -e
+set -x
+set -euxo pipefail
+
+handle_term()
+{
+    echo "received TERM signal"
+    echo "stopping nginx-agent ..."
+    kill -TERM "${agent_pid}" 2>/dev/null
+    echo "stopping nginx ..."
+    kill -TERM "${nginx_pid}" 2>/dev/null
+}
+
+trap 'handle_term' TERM
+
+# Launch nginx
+echo "starting nginx ..."
+/usr/local/nginx/sbin/nginx -g "daemon off;" &
+
+nginx_pid=$!
+
+cp /agent/nginx-agent.conf /etc/nginx-agent/nginx-agent.conf
+cat /etc/nginx-agent/nginx-agent.conf
+
+# start nginx-agent, pass args
+echo "starting nginx-agent ..."
+nginx-agent "$@" &
+
+agent_pid=$!
+
+if [ $? != 0 ]; then
+    echo "couldn't start the agent, please check the log file"
+    exit 1
+fi
+
+wait_term()
+{
+    wait ${agent_pid}
+    trap - TERM
+    kill -QUIT "${nginx_pid}" 2>/dev/null
+    echo "waiting for nginx to stop..."
+    wait ${nginx_pid}
+}
+
+wait_term
+
+echo "nginx-agent process has stopped, exiting."

examples/grafana-metrics/grafana-dashboards.yml

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+apiVersion: 1
+
+providers:
+  - name: 'dashboards'
+    type: file
+    disableDeletion: false
+    editable: true
+    allowUiUpdates: true
+    updateIntervalSeconds: 10
+    folder: "NGINX"
+    options:
+      path: /var/lib/grafana/dashboards
+      foldersFromFilesStructure: false

examples/grafana-metrics/grafana-datasources.yml

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+apiVersion: 1
+
+deleteDatasources:
+  - name: Prometheus
+    orgId: 1
+
+datasources:
+  - name: Prometheus
+    type: prometheus
+    typeName: Prometheus
+    typeLogoUrl: public/app/plugins/datasource/prometheus/img/prometheus_logo.svg
+    access: proxy
+    url: http://prometheus:9090
+    user: ""
+    database: ""
+    basicAuth: false
+    isDefault: true
+    jsonData: 
+      httpMethod: POST
+      readOnly: false