The main use case for Traefik in this scenario is to distribute incoming HTTP(S) and TCP requests from the Internet to front-end services that can handle these requests. This tutorial will show you one such example using a demo web application.
Traefik can natively integrate with Consul using the Consul Catalog Provider and can use tags to route traffic.
»Reference Material
»Prerequisites
To perform the tasks described in this guide, you need to have a Nomad environment with Consul installed. You can use this Terraform environment to provision a sandbox environment. This tutorial will assume a cluster with one server node and three client nodes.
Note: This tutorial is for demo purposes and only assumes a single server node. Please consult the reference architecture for production configuration.
»Steps
»Step 1: Create a Job for Demo Web App
Create a job for a demo web application and name the file webapp.nomad
:
job "demo-webapp" {
datacenters = ["dc1"]
group "demo" {
count = 3
task "server" {
env {
PORT = "${NOMAD_PORT_http}"
NODE_IP = "${NOMAD_IP_http}"
}
driver = "docker"
config {
image = "hashicorp/demo-webapp-lb-guide"
}
resources {
network {
mbits = 10
port "http"{}
}
}
service {
name = "demo-webapp"
port = "http"
tags = [
"traefik.enable=true",
"traefik.http.routers.http.rule=Path(`/myapp`)",
]
check {
type = "http"
path = "/"
interval = "2s"
timeout = "2s"
}
}
}
}
}
Note that this job deploys 3 instances of our demo web application which we will load balance with Traefik in the next few steps.
We are using tags to configure routing to our web app. Even though our application listens on
/
, it is possible to define/myapp
as the route because of thePath
option.
»Step 2: Deploy the Demo Web App
We can now deploy our demo web application:
$ nomad run webapp.nomad
==> Monitoring evaluation "a2061ab7"
Evaluation triggered by job "demo-webapp"
Evaluation within deployment: "8ca6d358"
Allocation "1d14babe" created: node "2d6eea6e", group "demo"
Allocation "3abb950d" created: node "a62fa99d", group "demo"
Allocation "c65e14bf" created: node "a209a662", group "demo"
Evaluation status changed: "pending" -> "complete"
==> Evaluation "a2061ab7" finished with status "complete"
»Step 3: Create a Job for Traefik
Create a job for Traefik and name it traefik.nomad
. This will be our load
balancer that will balance requests to the deployed instances of our web
application.
job "traefik" {
region = "global"
datacenters = ["dc1"]
type = "service"
group "traefik" {
count = 1
task "traefik" {
driver = "docker"
config {
image = "traefik:v2.2"
network_mode = "host"
volumes = [
"local/traefik.toml:/etc/traefik/traefik.toml",
]
}
template {
data = <<EOF
[entryPoints]
[entryPoints.http]
address = ":8080"
[entryPoints.traefik]
address = ":8081"
[api]
dashboard = true
insecure = true
# Enable Consul Catalog configuration backend.
[providers.consulCatalog]
prefix = "traefik"
exposedByDefault = false
[providers.consulCatalog.endpoint]
address = "127.0.0.1:8500"
scheme = "http"
EOF
destination = "local/traefik.toml"
}
resources {
cpu = 100
memory = 128
network {
mbits = 10
port "http" {
static = 8080
}
port "api" {
static = 8081
}
}
}
service {
name = "traefik"
check {
name = "alive"
type = "tcp"
port = "http"
interval = "10s"
timeout = "2s"
}
}
}
}
}
We have statically set the port of our load balancer to
8080
. This will allow us to querytraefik.service.consul:8080
at the appropriate paths (as configured in the tags section ofwebapp.nomad
from anywhere inside our cluster so we can reach our web application.The Traefik dashboard is configured at port
8081
.Please note that although we have defined the template inline, we could alternatively use the template stanza in conjunction with the artifact stanza to download an input template from a remote source such as an S3 bucket.
»Step 4: Run the Traefik Job
We can now register our Traefik job:
$ nomad run traefik.nomad
==> Monitoring evaluation "e22ce276"
Evaluation triggered by job "traefik"
Evaluation within deployment: "c6466497"
Allocation "695c5632" created: node "a62fa99d", group "traefik"
Evaluation status changed: "pending" -> "complete"
==> Evaluation "e22ce276" finished with status "complete"
»Step 5: Check the Traefik Dashboard
You can visit the dashboard for Traefik at
http://<Your-Traefik-IP-address>:8081
. You can use this page to verify your
settings and for basic monitoring.
»Step 6: Make a Request to the Load Balancer
If you query the Traefik load balancer, you should be able to see a response similar to the one shown below (this command should be run from a node inside your cluster):
$ curl http://traefik.service.consul:8080/myapp
Welcome! You are on node 172.31.28.103:28893
Note that your request has been forwarded to one of the several deployed instances of the demo web application (which is spread across 3 Nomad clients). The output shows the IP address of the host it is deployed on. If you repeat your requests, you will see that the IP address changes.
Note: If you would like to access Traefik from outside your cluster, you
can set up a load balancer in your environment that maps to an active port
8080
on your clients (or whichever port you have configured for Traefik to
listen on). You can then send your requests directly to your external load
balancer.