Nomad HAProxy load balancing guide (#6534)
* add nginx to load balancing nav menu and fix bullets * fill out nginx lb guide * formatting * change Nginx to NGINX * add step to verify load balancer config * update docker image and web app output * add HAProxy lb guide * format haproxy config * add haproxy stats page with screenshot * add note about external load balancer * Update website/source/guides/load-balancing/haproxy.html.md Co-Authored-By: Chris Baker <1675087+cgbaker@users.noreply.github.com> * Update website/source/guides/load-balancing/haproxy.html.md Co-Authored-By: Chris Baker <1675087+cgbaker@users.noreply.github.com> * Update website/source/guides/load-balancing/haproxy.html.md Co-Authored-By: Chris Baker <1675087+cgbaker@users.noreply.github.com> * Update website/source/guides/load-balancing/haproxy.html.md Co-Authored-By: Chris Baker <1675087+cgbaker@users.noreply.github.com> * Update website/source/guides/load-balancing/haproxy.html.md Co-Authored-By: Chris Baker <1675087+cgbaker@users.noreply.github.com> * Update website/source/guides/load-balancing/haproxy.html.md Co-Authored-By: Chris Baker <1675087+cgbaker@users.noreply.github.com> * Update website/source/guides/load-balancing/haproxy.html.md Co-Authored-By: Chris Baker <1675087+cgbaker@users.noreply.github.com> * Update website/source/guides/load-balancing/haproxy.html.md Co-Authored-By: Chris Baker <1675087+cgbaker@users.noreply.github.com> * add port mapping an static port for haproxy ui + bullet changes * remove extra spaces * Update website/source/guides/load-balancing/haproxy.html.md Co-Authored-By: Chris Baker <1675087+cgbaker@users.noreply.github.com> * Update website/source/guides/load-balancing/haproxy.html.md Co-Authored-By: Chris Baker <1675087+cgbaker@users.noreply.github.com> * Update website/source/guides/load-balancing/haproxy.html.md Co-Authored-By: Chris Baker <1675087+cgbaker@users.noreply.github.com>
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---
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layout: "guides"
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page_title: "Load Balancing with HAProxy"
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sidebar_current: "guides-load-balancing-haproxy"
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description: |-
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There are multiple approaches to load balancing within a Nomad cluster.
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One approach involves using [HAProxy][haproxy] which natively integrates with
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service discovery data from Consul.
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---
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# Load Balancing with HAProxy
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The main use case for HAProxy in this scenario is to distribute incoming HTTP(S)
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and TCP requests from the internet to frontend services that can handle these
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requests. This guide will show you one such example using a demo web
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application.
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HAProxy version 1.8+ (LTS) includes the [server-template] directive, which lets
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users specify placeholder backend servers to populate HAProxy’s load balancing
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pools. Server-template can use Consul as one of these backend servers,
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requesting SRV records from Consul DNS.
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## Reference Material
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- [HAProxy][haproxy]
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- [Load Balancing Strategies for Consul][lb-strategies]
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## Estimated Time to Complete
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20 minutes
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## Prerequisites
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To perform the tasks described in this guide, you need to have a Nomad
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environment with Consul installed. You can use this [repo][terraform-repo] to
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easily provision a sandbox environment. This guide will assume a cluster with
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one server node and three client nodes.
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-> **Note:** This guide is for demo purposes and only assumes a single server
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node. Please consult the [reference architecture][reference-arch] for production
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configuration.
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## Steps
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### Step 1: Create a Job for Demo Web App
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Create a job for a demo web application and name the file 'webapp.nomad':
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```hcl
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job "demo-webapp" {
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datacenters = ["dc1"]
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group "demo" {
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count = 3
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task "server" {
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env {
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PORT = "${NOMAD_PORT_http}"
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NODE_IP = "${NOMAD_IP_http}"
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}
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driver = "docker"
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config {
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image = "hashicorp/demo-webapp-lb-guide"
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}
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resources {
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network {
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mbits = 10
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port "http" {}
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}
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}
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service {
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name = "demo-webapp"
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port = "http"
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check {
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type = "http"
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path = "/"
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interval = "2s"
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timeout = "2s"
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}
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}
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}
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}
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}
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```
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Note that this job deploys 3 instances of our demo web application which we will
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load balance with HAProxy in the next few steps.
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### Step 2: Deploy the Demo Web App
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We can now deploy our demo web application:
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```shell
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$ nomad run webapp.nomad
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==> Monitoring evaluation "8f3af425"
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Evaluation triggered by job "demo-webapp"
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Evaluation within deployment: "dc4c1925"
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Allocation "bf9f850f" created: node "d16a11fb", group "demo"
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Allocation "25e0496a" created: node "b78e27be", group "demo"
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Allocation "a97e7d39" created: node "01d3eb32", group "demo"
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Evaluation status changed: "pending" -> "complete"
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==> Evaluation "8f3af425" finished with status "complete"
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```
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### Step 3: Create a Job for HAProxy
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Create a job for HAProxy and name it `haproxy.nomad`. This will be our load
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balancer that will balance requests to the deployed instances of our web
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application.
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```hcl
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job "haproxy" {
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region = "global"
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datacenters = ["dc1"]
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type = "service"
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group "haproxy" {
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count = 1
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task "haproxy" {
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driver = "docker"
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config {
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image = "haproxy:2.0"
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network_mode = "host"
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port_map {
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http = 8080
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haproxy_ui = 1936
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}
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volumes = [
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"local/haproxy.cfg:/usr/local/etc/haproxy/haproxy.cfg",
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]
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}
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template {
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data = <<EOF
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defaults
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mode http
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frontend stats
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bind *:1936
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stats uri /
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stats show-legends
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no log
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frontend http_front
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bind *:8080
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default_backend http_back
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backend http_back
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balance roundrobin
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server-template mywebapp 10 _demo-webapp._tcp.service.consul resolvers consul resolve-opts allow-dup-ip resolve-prefer ipv4 check
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resolvers consul
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nameserver consul 127.0.0.1:53
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accepted_payload_size 8192
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hold valid 5s
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EOF
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destination = "local/haproxy.cfg"
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}
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service {
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name = "haproxy"
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port = "http"
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}
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resources {
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cpu = 200
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memory = 128
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network {
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mbits = 10
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port "http" {
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static = 8080
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}
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port "haproxy_ui" {
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static = 1936
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}
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}
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}
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}
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}
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}
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```
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Take note of the following key points from the HAProxy configuration we have
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defined:
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- The `balance type` under the `backend http_back` stanza in the HAProxy config
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is round robin and will load balance across the available service in order.
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- The `server-template` option allows Consul service registrations to configure
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HAProxy's backend server pool. Because of this, you do not need to explicitly
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add your backend servers' IP addresses. We have specified a server-template
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named mywebapp. The template name is not tied to the service name which is
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registered in Consul.
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- `_demo-webapp._tcp.service.consul` allows HAProxy to use the DNS SRV record for
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the backend service `demo-webapp.service.consul` to discover the available
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instances of the service.
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Additionally, keep in mind the following points from the Nomad job spec:
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- We have statically set the port of our load balancer to `8080`. This will
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allow us to query `haproxy.service.consul:8080` from anywhere inside our cluster
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so we can reach our web application.
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- Please note that although we have defined the template [inline][inline], we
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could alternatively use the template stanza [in conjunction with the artifact
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stanza][remote-template] to download an input template from a remote source
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such as an S3 bucket.
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### Step 4: Run the HAProxy Job
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We can now register our HAProxy job:
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```shell
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$ nomad run haproxy.nomad
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==> Monitoring evaluation "937b1a2d"
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Evaluation triggered by job "haproxy"
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Evaluation within deployment: "e8214434"
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Allocation "53145b8b" created: node "d16a11fb", group "haproxy"
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Evaluation status changed: "pending" -> "complete"
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==> Evaluation "937b1a2d" finished with status "complete"
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```
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### Step 5: Check the HAProxy Statistics Page
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You can visit the statistics and monitoring page for HAProxy at
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`http://<Your-HAProxy-IP-address>:1936`. You can use this page to verify your
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settings and for basic monitoring.
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[![Home Page][haproxy_ui]][haproxy_ui]
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Notice there are 10 pre-provisioned load balancer backend slots for your service
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but that only three of them are being used, corresponding to the three allocations in the current job.
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### Step 6: Make a Request to the Load Balancer
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If you query the HAProxy load balancer, you should be able to see a response
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similar to the one shown below (this command should be run from a
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node inside your cluster):
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```shell
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$ curl haproxy.service.consul:8080
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Welcome! You are on node 172.31.54.242:20124
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```
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Note that your request has been forwarded to one of the several deployed
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instances of the demo web application (which is spread across 3 Nomad clients).
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The output shows the IP address of the host it is deployed on. If you repeat
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your requests, you will see that the IP address changes.
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* Note: if you would like to access HAProxy from outside your cluster, you
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can set up a load balancer in your environment that maps to an active port
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`8080` on your clients (or whichever port you have configured for HAProxy to
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listen on). You can then send your requests directly to your external load
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balancer.
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[consul-template]: https://github.com/hashicorp/consul-template#consul-template
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[consul-temp-syntax]: https://github.com/hashicorp/consul-template#service
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[haproxy]: http://www.haproxy.org/
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[haproxy_ui]: /assets/images/haproxy_ui.png
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[inline]: /docs/job-specification/template.html#inline-template
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[lb-strategies]: https://www.hashicorp.com/blog/configuring-third-party-loadbalancers-with-consul-nginx-haproxy-f5/
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[reference-arch]: /guides/install/production/reference-architecture.html#high-availability
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[remote-template]: /docs/job-specification/template.html#remote-template
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[server-template]: https://www.haproxy.com/blog/whats-new-haproxy-1-8/#server-template-configuration-directive
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[template-stanza]: /docs/job-specification/template.html
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[terraform-repo]: https://github.com/hashicorp/nomad/tree/master/terraform#provision-a-nomad-cluster-in-the-cloud
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@ -17,6 +17,7 @@ Consul](https://www.hashicorp.com/blog/load-balancing-strategies-for-consul)).
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- [Fabio](/guides/load-balancing/fabio.html)
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- [NGINX](/guides/load-balancing/nginx.html)
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- [HAProxy](/guides/load-balancing/haproxy.html)
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Please refer to the specific documentation above or in the sidebar for more
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detailed information about each strategy.
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@ -264,6 +264,11 @@
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<a href="/guides/load-balancing/nginx.html">NGINX</a>
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</li>
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</ul>
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<ul class="nav">
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<li<%= sidebar_current("guides-load-balancing-haproxy") %>>
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<a href="/guides/load-balancing/haproxy.html">HAProxy</a>
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</li>
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</ul>
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</li>
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<li<%= sidebar_current("guides-governance-and-policy") %>>
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