e948e0a012
During testing we discovered old versions of Nomad and Consul seemed to prevent Envoy from accepting new connections while the Nomad agent was being upgraded.
338 lines
8.5 KiB
Plaintext
338 lines
8.5 KiB
Plaintext
---
|
|
layout: docs
|
|
page_title: Consul Connect
|
|
sidebar_title: Consul Connect
|
|
description: >-
|
|
Learn how to use Nomad with Consul Connect to enable secure service to service
|
|
communication
|
|
---
|
|
|
|
# Consul Connect
|
|
|
|
~> **Note:** This guide requires Nomad 0.10.0 or later and Consul 1.6.0 or
|
|
later.
|
|
|
|
~> **Note:** Nomad's Connect integration requires Linux network namespaces.
|
|
Nomad Connect will not run on Windows or macOS.
|
|
|
|
[Consul Connect](https://www.consul.io/docs/connect) provides
|
|
service-to-service connection authorization and encryption using mutual
|
|
Transport Layer Security (TLS). Applications can use sidecar proxies in a
|
|
service mesh configuration to automatically establish TLS connections for
|
|
inbound and outbound connections without being aware of Connect at all.
|
|
|
|
# Nomad with Consul Connect Integration
|
|
|
|
Nomad integrates with Consul to provide secure service-to-service communication
|
|
between Nomad jobs and task groups. In order to support Consul Connect, Nomad
|
|
adds a new networking mode for jobs that enables tasks in the same task group to
|
|
share their networking stack. With a few changes to the job specification, job
|
|
authors can opt into Connect integration. When Connect is enabled, Nomad will
|
|
launch a proxy alongside the application in the job file. The proxy (Envoy)
|
|
provides secure communication with other applications in the cluster.
|
|
|
|
Nomad job specification authors can use Nomad's Consul Connect integration to
|
|
implement [service segmentation](https://www.consul.io/use-cases/multi-platform-service-mesh) in a
|
|
microservice architecture running in public clouds without having to directly
|
|
manage TLS certificates. This is transparent to job specification authors as
|
|
security features in Connect continue to work even as the application scales up
|
|
or down or gets rescheduled by Nomad.
|
|
|
|
For using the Consul Connect integration with Consul ACLs enabled, see the
|
|
[Secure Nomad Jobs with Consul Connect](https://learn.hashicorp.com/tutorials/nomad/consul-service-mesh)
|
|
guide.
|
|
|
|
# Nomad Consul Connect Example
|
|
|
|
The following section walks through an example to enable secure communication
|
|
between a web dashboard and a backend counting service. The web dashboard and
|
|
the counting service are managed by Nomad. Nomad additionally configures Envoy
|
|
proxies to run along side these applications. The dashboard is configured to
|
|
connect to the counting service via localhost on port 9001. The proxy is managed
|
|
by Nomad, and handles mTLS communication to the counting service.
|
|
|
|
## Prerequisites
|
|
|
|
### Consul
|
|
|
|
Connect integration with Nomad requires [Consul 1.6 or
|
|
later.](https://releases.hashicorp.com/consul/1.6.0/) The Consul agent can be
|
|
run in dev mode with the following command:
|
|
|
|
**Note**: Nomad's Connect integration requires Consul in your `$PATH`
|
|
|
|
```shell-session
|
|
$ consul agent -dev
|
|
```
|
|
|
|
To use Connect on a non-dev Consul agent, you will minimally need to enable the
|
|
GRPC port and set `connect` to enabled by adding some additional information to
|
|
your Consul client configurations, depending on format.
|
|
|
|
For HCL configurations:
|
|
|
|
```hcl
|
|
# ...
|
|
|
|
ports {
|
|
grpc = 8502
|
|
}
|
|
|
|
connect {
|
|
enabled = true
|
|
}
|
|
```
|
|
|
|
For JSON configurations:
|
|
|
|
```javascript
|
|
{
|
|
// ...
|
|
"ports": {
|
|
"grpc": 8502
|
|
},
|
|
"connect": {
|
|
"enabled": true
|
|
}
|
|
}
|
|
```
|
|
|
|
### Nomad
|
|
|
|
Nomad must schedule onto a routable interface in order for the proxies to
|
|
connect to each other. The following steps show how to start a Nomad dev agent
|
|
configured for Connect.
|
|
|
|
```shell-session
|
|
$ sudo nomad agent -dev-connect
|
|
```
|
|
|
|
### CNI Plugins
|
|
|
|
Nomad uses CNI plugins to configure the network namespace used to secure the
|
|
Consul Connect sidecar proxy. All Nomad client nodes using network namespaces
|
|
must have CNI plugins installed.
|
|
|
|
The following commands install CNI plugins:
|
|
|
|
```shell-session
|
|
$ curl -L -o cni-plugins.tgz https://github.com/containernetworking/plugins/releases/download/v0.8.6/cni-plugins-linux-amd64-v0.8.6.tgz
|
|
$ sudo mkdir -p /opt/cni/bin
|
|
$ sudo tar -C /opt/cni/bin -xzf cni-plugins.tgz
|
|
```
|
|
|
|
Ensure the your Linux operating system distribution has been configured to allow
|
|
container traffic through the bridge network to be routed via iptables. These
|
|
tunables can be set as follows:
|
|
|
|
```shell-session
|
|
$ echo 1 > /proc/sys/net/bridge/bridge-nf-call-arptables
|
|
$ echo 1 > /proc/sys/net/bridge/bridge-nf-call-ip6tables
|
|
$ echo 1 > /proc/sys/net/bridge/bridge-nf-call-iptables
|
|
```
|
|
|
|
To preserve these settings on startup of a client node, add a file including the
|
|
following to `/etc/sysctl.d/` or remove the file your Linux distribution puts in
|
|
that directory.
|
|
|
|
```
|
|
net.bridge.bridge-nf-call-arptables = 1
|
|
net.bridge.bridge-nf-call-ip6tables = 1
|
|
net.bridge.bridge-nf-call-iptables = 1
|
|
```
|
|
|
|
## Run the Connect-enabled Services
|
|
|
|
Once Nomad and Consul are running, submit the following Connect-enabled services
|
|
to Nomad by copying the HCL into a file named `connect.nomad` and running:
|
|
`nomad run connect.nomad`
|
|
|
|
```hcl
|
|
job "countdash" {
|
|
datacenters = ["dc1"]
|
|
|
|
group "api" {
|
|
network {
|
|
mode = "bridge"
|
|
}
|
|
|
|
service {
|
|
name = "count-api"
|
|
port = "9001"
|
|
|
|
connect {
|
|
sidecar_service {}
|
|
}
|
|
}
|
|
|
|
task "web" {
|
|
driver = "docker"
|
|
|
|
config {
|
|
image = "hashicorpnomad/counter-api:v1"
|
|
}
|
|
}
|
|
}
|
|
|
|
group "dashboard" {
|
|
network {
|
|
mode = "bridge"
|
|
|
|
port "http" {
|
|
static = 9002
|
|
to = 9002
|
|
}
|
|
}
|
|
|
|
service {
|
|
name = "count-dashboard"
|
|
port = "9002"
|
|
|
|
connect {
|
|
sidecar_service {
|
|
proxy {
|
|
upstreams {
|
|
destination_name = "count-api"
|
|
local_bind_port = 8080
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
task "dashboard" {
|
|
driver = "docker"
|
|
|
|
env {
|
|
COUNTING_SERVICE_URL = "http://${NOMAD_UPSTREAM_ADDR_count_api}"
|
|
}
|
|
|
|
config {
|
|
image = "hashicorpnomad/counter-dashboard:v1"
|
|
}
|
|
}
|
|
}
|
|
}
|
|
```
|
|
|
|
The job contains two task groups: an API service and a web frontend.
|
|
|
|
### API Service
|
|
|
|
The API service is defined as a task group with a bridge network:
|
|
|
|
```hcl
|
|
group "api" {
|
|
network {
|
|
mode = "bridge"
|
|
}
|
|
|
|
# ...
|
|
}
|
|
```
|
|
|
|
Since the API service is only accessible via Consul Connect, it does not define
|
|
any ports in its network. The service stanza enables Connect:
|
|
|
|
```hcl
|
|
group "api" {
|
|
|
|
# ...
|
|
|
|
service {
|
|
name = "count-api"
|
|
port = "9001"
|
|
|
|
connect {
|
|
sidecar_service {}
|
|
}
|
|
}
|
|
|
|
# ...
|
|
|
|
}
|
|
```
|
|
|
|
The `port` in the service stanza is the port the API service listens on. The
|
|
Envoy proxy will automatically route traffic to that port inside the network
|
|
namespace.
|
|
|
|
### Web Frontend
|
|
|
|
The web frontend is defined as a task group with a bridge network and a static
|
|
forwarded port:
|
|
|
|
```hcl
|
|
group "dashboard" {
|
|
network {
|
|
mode = "bridge"
|
|
|
|
port "http" {
|
|
static = 9002
|
|
to = 9002
|
|
}
|
|
}
|
|
|
|
# ...
|
|
|
|
}
|
|
```
|
|
|
|
The `static = 9002` parameter requests the Nomad scheduler reserve port 9002 on
|
|
a host network interface. The `to = 9002` parameter forwards that host port to
|
|
port 9002 inside the network namespace.
|
|
|
|
This allows you to connect to the web frontend in a browser by visiting
|
|
`http://<host_ip>:9002` as show below:
|
|
|
|
[![Count Dashboard][count-dashboard]][count-dashboard]
|
|
|
|
The web frontend connects to the API service via Consul Connect:
|
|
|
|
```hcl
|
|
service {
|
|
name = "count-dashboard"
|
|
port = "9002"
|
|
|
|
connect {
|
|
sidecar_service {
|
|
proxy {
|
|
upstreams {
|
|
destination_name = "count-api"
|
|
local_bind_port = 8080
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
```
|
|
|
|
The `upstreams` stanza defines the remote service to access (`count-api`) and
|
|
what port to expose that service on inside the network namespace (`8080`).
|
|
|
|
The web frontend is configured to communicate with the API service with an
|
|
environment variable:
|
|
|
|
```hcl
|
|
env {
|
|
COUNTING_SERVICE_URL = "http://${NOMAD_UPSTREAM_ADDR_count_api}"
|
|
}
|
|
```
|
|
|
|
The web frontend is configured via the `$COUNTING_SERVICE_URL`, so you must
|
|
interpolate the upstream's address into that environment variable. Note that
|
|
dashes (`-`) are converted to underscores (`_`) in environment variables so
|
|
`count-api` becomes `count_api`.
|
|
|
|
## Limitations
|
|
|
|
- The `consul` binary must be present in Nomad's `$PATH` to run the Envoy
|
|
proxy sidecar on client nodes.
|
|
- Consul Connect using network namespaces is only supported on Linux.
|
|
- Prior to Nomad 1.0 and Consul 1.9, the Envoy sidecar proxy may drop and stop
|
|
accepting connections while the Nomad agent is restarting.
|
|
|
|
[count-dashboard]: /img/count-dashboard.png
|
|
[gh6120]: https://github.com/hashicorp/nomad/issues/6120
|
|
[gh6701]: https://github.com/hashicorp/nomad/issues/6701
|