mirror of https://github.com/hashicorp/consul
264 lines
9.1 KiB
Markdown
264 lines
9.1 KiB
Markdown
---
|
|
layout: intro
|
|
page_title: Consul Connect
|
|
description: >-
|
|
Connect is a feature of Consul that provides service-to-service connection
|
|
authorization and encryption using mutual TLS. This ensures that all service
|
|
communication in your datacenter is encrypted and that the rules of what
|
|
services can communicate is centrally managed with Consul.
|
|
---
|
|
|
|
# Connect
|
|
|
|
We've now registered our first service with Consul and we've shown how you
|
|
can use the HTTP API or DNS interface to query the address and directly connect
|
|
to that service. Consul also provides a feature called **Connect** for
|
|
automatically connecting via an encrypted TLS connection and authorizing
|
|
which services are allowed to connect to each other.
|
|
|
|
Applications do not need to be modified at all to use Connect.
|
|
[Sidecar proxies](/docs/connect/proxies) can be used
|
|
to automatically establish TLS connections for inbound and outbound connections
|
|
without being aware of Connect at all. Applications may also
|
|
[natively integrate with Connect](/docs/connect/native)
|
|
for optimal performance and security.
|
|
|
|
-> **Security note:** The getting started guide will show Connect features and
|
|
focus on ease of use with a dev-mode agent. We will _not setup_ Connect in a
|
|
production-recommended secure way. Please read the [Connect production
|
|
guide](/docs/guides/connect-production) to understand the tradeoffs.
|
|
|
|
## Starting a Connect-unaware Service
|
|
|
|
Let's begin by starting a service that is unaware of Connect. To keep it simple,
|
|
let's just use `socat` to start a basic echo service. This service will accept
|
|
TCP connections and echo back any data sent to it. If `socat` isn't installed on
|
|
your machine, it should be easily available via a package manager.
|
|
|
|
```shell-session
|
|
$ socat -v tcp-l:8181,fork exec:"/bin/cat"
|
|
```
|
|
|
|
You can verify it is working by using `nc` to connect directly to it. Once
|
|
connected, type some text and press enter. The text you typed should be
|
|
echoed back:
|
|
|
|
```shell-session
|
|
$ nc 127.0.0.1 8181
|
|
hello
|
|
hello
|
|
echo
|
|
echo
|
|
```
|
|
|
|
`socat` is a decades-old Unix utility and our process is configured to
|
|
only accept a basic TCP connection. It has no concept of encryption, the
|
|
TLS protocol, etc. This can be representative of an existing service in
|
|
your datacenter such as a database, backend web service, etc.
|
|
|
|
## Registering the Service with Consul and Connect
|
|
|
|
Next, let's register the service with Consul. We'll do this by writing
|
|
a new service definition. This is the same as the previous step in the
|
|
getting started guide, except this time we'll also configure Connect.
|
|
|
|
```shell-session
|
|
$ cat <<EOF | sudo tee /etc/consul.d/socat.json
|
|
{
|
|
"service": {
|
|
"name": "socat",
|
|
"port": 8181,
|
|
"connect": { "sidecar_service": {} }
|
|
}
|
|
}
|
|
EOF
|
|
```
|
|
|
|
After saving this, run `consul reload` or send a `SIGHUP` signal to Consul
|
|
so it reads the new configuration.
|
|
|
|
Notice the only difference is the line starting with `"connect"`. The existence
|
|
of this empty configuration notifies Consul to register a sidecar proxy for this
|
|
process. The proxy process represents that specific service. It accepts inbound
|
|
connections on a dynamically allocated port, verifies and authorizes the TLS
|
|
connection, and proxies back a standard TCP connection to the process.
|
|
|
|
The sidecar service registration here is just telling Consul that a proxy should
|
|
be running, Consul won't actually run a proxy process for you.
|
|
|
|
We need to start the proxy process in another terminal:
|
|
|
|
```shell-session
|
|
$ consul connect proxy -sidecar-for socat
|
|
==> Consul Connect proxy starting...
|
|
Configuration mode: Agent API
|
|
Sidecar for ID: socat
|
|
Proxy ID: socat-sidecar-proxy
|
|
|
|
...
|
|
```
|
|
|
|
## Connecting to the Service
|
|
|
|
Next, let's connect to the service. We'll first do this by using the `consul connect proxy` command again directly. This time we use the command to configure
|
|
and run a local proxy that can represent a service. This is a useful tool for
|
|
development since it'll let you masquerade as any service (that you have
|
|
permissions for) and establish connections to other services via Connect.
|
|
|
|
The command below starts a proxy representing a service "web". We request
|
|
an upstream dependency of "socat" (the service we previously registered)
|
|
on port 9191. With this configuration, all TCP connections to 9191 will
|
|
perform service discovery for a Connect-capable "socat" endpoint and establish
|
|
a mutual TLS connection identifying as the service "web".
|
|
|
|
```shell-session
|
|
$ consul connect proxy -service web -upstream socat:9191
|
|
==> Consul Connect proxy starting...
|
|
Configuration mode: Flags
|
|
Service: web
|
|
Upstream: socat => :9191
|
|
Public listener: Disabled
|
|
|
|
...
|
|
```
|
|
|
|
With that running, we can verify it works by establishing a connection:
|
|
|
|
```shell-session
|
|
$ nc 127.0.0.1 9191
|
|
hello
|
|
hello
|
|
```
|
|
|
|
**The connection between proxies is now encrypted and authorized.**
|
|
We're now communicating to the "socat" service via a TLS connection.
|
|
The local connections to/from the proxy are unencrypted, but in production
|
|
these will be loopback-only connections. Any traffic in and out of the
|
|
machine is always encrypted.
|
|
|
|
## Registering a Dependent Service
|
|
|
|
We previously established a connection by directly running `consul connect proxy` in developer mode. Realistically, services need to establish connections
|
|
to dependencies over Connect. Let's register a service "web" that registers
|
|
"socat" as an upstream dependency in its sidecar registration:
|
|
|
|
```shell-session
|
|
$ cat <<EOF | sudo tee /etc/consul.d/web.json
|
|
{
|
|
"service": {
|
|
"name": "web",
|
|
"port": 8080,
|
|
"connect": {
|
|
"sidecar_service": {
|
|
"proxy": {
|
|
"upstreams": [{
|
|
"destination_name": "socat",
|
|
"local_bind_port": 9191
|
|
}]
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
EOF
|
|
```
|
|
|
|
This registers a sidecar proxy for the service "web" that
|
|
should listen on port 9191 to establish connections to "socat" as "web". The
|
|
"web" service should then use that local port to talk to socat rather than
|
|
directly attempting to connect.
|
|
|
|
With that file in place, use `consul reload` or SIGHUP to reload Consul. If the
|
|
proxy command from the previous section (with the inline upstream listener) is
|
|
still running, stop it with `Ctrl-C`. Now we can start the web proxy using the
|
|
configuration from the sidecar registration as we did for socat.
|
|
|
|
```shell-session
|
|
$ consul connect proxy -sidecar-for web
|
|
==> Consul Connect proxy starting...
|
|
Configuration mode: Agent API
|
|
Sidecar for ID: web
|
|
Proxy ID: web-sidecar-proxy
|
|
|
|
==> Log data will now stream in as it occurs:
|
|
|
|
2018/10/09 12:34:20 [INFO] 127.0.0.1:9191->service:default/socat starting on 127.0.0.1:9191
|
|
2018/10/09 12:34:20 [INFO] Proxy loaded config and ready to serve
|
|
2018/10/09 12:34:20 [INFO] TLS Identity: spiffe://df34ef6b-5971-ee61-0790-ca8622c3c287.consul/ns/default/dc/dc1/svc/web
|
|
2018/10/09 12:34:20 [INFO] TLS Roots : [Consul CA 7]
|
|
```
|
|
|
|
Note in the first log line that the proxy discovered its configuration from the
|
|
local agent and setup a local listener on port 9191 that will proxy to the socat
|
|
service just as we configured in the sidecar registration.
|
|
|
|
You can also see the identity URL from the certificate it loaded from the agent
|
|
identifying it as the "web" service and the set of trusted root CAs it knows
|
|
about.
|
|
|
|
-> **Security note:** The Connect security model requires trusting
|
|
loopback connections when proxies are in use. To further secure this,
|
|
tools like network namespacing may be used.
|
|
|
|
We can verify it works by establishing a new connection:
|
|
|
|
```shell-session
|
|
$ nc 127.0.0.1 9191
|
|
hello
|
|
hello
|
|
```
|
|
|
|
## Controlling Access with Intentions
|
|
|
|
Intentions are used to define which services may communicate. Our connections
|
|
above succeeded because in a development mode agent, the ACL system is "allow
|
|
all" by default.
|
|
|
|
Let's insert a rule to deny access from web to socat:
|
|
|
|
```shell-session
|
|
$ consul intention create -deny web socat
|
|
Created: web => socat (deny)
|
|
```
|
|
|
|
With the proxy processes running that we setup previously, connection
|
|
attempts now fail:
|
|
|
|
```shell-session
|
|
$ nc 127.0.0.1 9191
|
|
$
|
|
```
|
|
|
|
Try deleting the intention and attempt the connection again.
|
|
|
|
```shell-session
|
|
$ consul intention delete web socat
|
|
Intention deleted.
|
|
$ nc 127.0.0.1 9191
|
|
hello
|
|
hello
|
|
```
|
|
|
|
Intentions allow services to be segmented via a centralized control plane
|
|
(Consul). To learn more, read the reference documentation on
|
|
[intentions](/docs/connect/intentions).
|
|
|
|
Note that in the current release of Consul, changing intentions will not
|
|
affect existing connections. Therefore, you must establish a new connection
|
|
to see the effects of a changed intention. This will be addressed in the near
|
|
term in a future version of Consul.
|
|
|
|
## Discover More Connect
|
|
|
|
This quick guide has given a taste of what Connect can do but there is much
|
|
more. Take a look at [getting started with
|
|
Connect](/docs/connect#getting-started-with-connect) for more guides
|
|
on setting up Connect with Envoy proxy, with Docker and in Kubernetes.
|
|
|
|
## Next Steps
|
|
|
|
We've now configured a service on a single agent and used Connect for
|
|
automatic connection authorization and encryption. This is a great feature
|
|
highlight but let's explore the full value of Consul by [setting up our
|
|
first cluster](/intro/getting-started/join)!
|