mirror of https://github.com/status-im/consul.git
201 lines
10 KiB
Plaintext
201 lines
10 KiB
Plaintext
---
|
|
layout: docs
|
|
page_title: Connect - Transparent Proxy
|
|
sidebar_title: Transparent Proxy
|
|
description: |-
|
|
Transparent proxy is used to direct inbound and outbound traffic to services via the Envoy proxy and configure
|
|
upstreams via intentions.
|
|
---
|
|
|
|
# Transparent Proxy
|
|
|
|
Transparent proxy allows users to reach other services in the service mesh while ensuring that inbound and outbound
|
|
traffic for services in the mesh are directed through the sidecar proxy. Traffic is secured
|
|
and only reaches intended destinations since the proxy can enforce security and policy like TLS and Service Intentions.
|
|
|
|
Previously, service mesh users would need to explicitly define upstreams for a service as a local listener on the sidecar
|
|
proxy, and dial the local listener to reach the appropriate upstream. Users would also have to set intentions to allow
|
|
specific services to talk to one another. Transparent proxying reduces this duplication, by determining upstreams
|
|
implicitly from Service Intentions. Explicit upstreams are still supported in the [proxy service
|
|
registration](/docs/connect/registration/service-registration) on VMs and via the
|
|
[annotation](/docs/k8s/connect#consul-hashicorp-com-connect-service-upstreams) in Kubernetes.
|
|
|
|
To support transparent proxying, Consul's CLI now has a command
|
|
[`consul connect redirect-traffic`](/commands/connect/redirect-traffic) to redirect traffic through an inbound and
|
|
outbound listener on the sidecar. Consul also watches Service Intentions and configures the Envoy proxy with the appropriate
|
|
upstream IPs. If the default ACL policy is "allow", then Service Intentions are not required. In Consul on Kubernetes,
|
|
the traffic redirection command is automatically set up via an init container.
|
|
|
|
## Prerequisites
|
|
|
|
### Kubernetes
|
|
|
|
* To use transparent proxy on Kubernetes, Consul-helm >= `0.32.0` and Consul-k8s >= `0.26.0` are required in addition to Consul >= `1.10.0`.
|
|
* If the default policy for ACLs is "deny", then Service Intentions should be set up to allow intended services to connect to each other.
|
|
Otherwise, all Connect services can talk to all other services.
|
|
|
|
The Kubernetes integration takes care of registering Kubernetes services with Consul, injecting a sidecar proxy, and
|
|
enabling traffic redirection.
|
|
|
|
## Upgrading to Transparent Proxy
|
|
|
|
~> When upgrading from older versions (i.e Consul-k8s < `0.26.0` or Consul-helm < `0.32.0`) to Consul-k8s >= `0.26.0` and Consul-helm >= `0.32.0`, please make sure to follow the upgrade steps [here](/docs/upgrading/upgrade-specific/#transparent-proxy-on-kubernetes).
|
|
|
|
## Configuration
|
|
|
|
### Enabling Transparent Proxy
|
|
Transparent proxy can be enabled in Kubernetes on the whole cluster via the Helm value:
|
|
|
|
```yaml
|
|
connectInject:
|
|
transparentProxy:
|
|
defaultEnabled: true
|
|
```
|
|
|
|
It can also be enabled on a per namespace basis by setting the label `consul.hashicorp.com/transparent-proxy=true` on the
|
|
Kubernetes namespace. This will override the Helm value `connectInject.transparentProxy.defaultEnabled` and define the
|
|
default behavior of Pods in the namespace. For example:
|
|
```bash
|
|
kubectl label namespaces my-app "consul.hashicorp.com/transparent-proxy=true"
|
|
```
|
|
|
|
It can also be enabled on a per service basis via the annotation `consul.hashicorp.com/transparent-proxy=true` on the
|
|
Pod for each service, which will override both the Helm value and the namespace label:
|
|
|
|
```yaml
|
|
apiVersion: v1
|
|
kind: Service
|
|
metadata:
|
|
name: static-server
|
|
spec:
|
|
selector:
|
|
app: static-server
|
|
ports:
|
|
- protocol: TCP
|
|
port: 80
|
|
targetPort: 8080
|
|
---
|
|
apiVersion: v1
|
|
kind: ServiceAccount
|
|
metadata:
|
|
name: static-server
|
|
---
|
|
apiVersion: apps/v1
|
|
kind: Deployment
|
|
metadata:
|
|
name: static-server
|
|
spec:
|
|
replicas: 1
|
|
selector:
|
|
matchLabels:
|
|
app: static-server
|
|
template:
|
|
metadata:
|
|
name: static-server
|
|
labels:
|
|
app: static-server
|
|
annotations:
|
|
'consul.hashicorp.com/connect-inject': 'true'
|
|
'consul.hashicorp.com/transparent-proxy': 'true'
|
|
spec:
|
|
containers:
|
|
- name: static-server
|
|
image: hashicorp/http-echo:latest
|
|
args:
|
|
- -text="hello world"
|
|
- -listen=:8080
|
|
ports:
|
|
- containerPort: 8080
|
|
name: http
|
|
serviceAccountName: static-server
|
|
```
|
|
|
|
### Kubernetes HTTP Health Probes Configuration
|
|
Traffic redirection interferes with [Kubernetes HTTP health
|
|
probes](https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/) since the
|
|
probes expect that kubelet can directly reach the application container on the probe's endpoint, but that traffic will
|
|
be redirected through the sidecar proxy, causing errors because kubelet itself is not encrypting that traffic using a
|
|
mesh proxy. For this reason, Consul allows you to [overwrite Kubernetes HTTP health probes](/docs/k8s/connect/health) to point to the proxy instead.
|
|
This can be done using the Helm value `connectInject.transparentProxy.defaultOverwriteProbes`
|
|
or the Pod annotation `consul.hashicorp.com/transparent-proxy-overwrite-probes`.
|
|
|
|
### Traffic Redirection Configuration
|
|
Pods with transparent proxy enabled will have an init container injected that sets up traffic redirection for all
|
|
inbound and outbound traffic through the sidecar proxies. This will include all traffic by default, with the ability to
|
|
configure exceptions on a per-Pod basis. The following Pod annotations allow you to exclude certain traffic from redirection to the sidecar proxies:
|
|
- [`consul.hashicorp.com/transparent-proxy-exclude-inbound-ports`](/docs/k8s/connect#consul-hashicorp-com-transparent-proxy-exclude-inbound-ports)
|
|
- [`consul.hashicorp.com/transparent-proxy-exclude-outbound-ports`](/docs/k8s/connect#consul-hashicorp-com-transparent-proxy-exclude-outbound-ports)
|
|
- [`consul.hashicorp.com/transparent-proxy-exclude-outbound-cidrs`](/docs/k8s/connect#consul-hashicorp-com-transparent-proxy-exclude-outbound-cidrs)
|
|
- [`consul.hashicorp.com/transparent-proxy-exclude-uids`](/docs/k8s/connect#consul-hashicorp-com-transparent-proxy-exclude-uids)
|
|
|
|
|
|
## Known Limitations
|
|
|
|
* Traffic can only be transparently proxied when the address dialed corresponds to the address of a service in the
|
|
transparent proxy's datacenter. Services can also dial explicit upstreams in other datacenters without transparent proxy, for example, by adding an
|
|
[annotation](/docs/k8s/connect#consul-hashicorp-com-connect-service-upstreams) such as
|
|
`"consul.hashicorp.com/connect-service-upstreams": "my-service:1234:dc2"` to reach an upstream service called `my-service`
|
|
in the datacenter `dc2`.
|
|
* In the deployment configuration where a [single Consul datacenter spans multiple Kubernetes clusters](/docs/k8s/installation/deployment-configurations/single-dc-multi-k8s), services in one Kubernetes cluster must explicitly dial a service in another Kubernetes cluster using the [consul.hashicorp.com/connect-service-upstreams](/docs/k8s/connect#consul-hashicorp-com-connect-service-upstreams) annotation. An example would be
|
|
`"consul.hashicorp.com/connect-service-upstreams": "my-service:1234"`, where `my-service` is the service that exists in another Kubernetes cluster and is exposed on port `1234`. Although Transparent Proxy is enabled, KubeDNS is not utilized when communicating between services existing on separate Kubernetes clusters.
|
|
* When dialing headless services the request will be proxied using a plain TCP proxy with a 5s connection timeout.
|
|
Currently the upstream's protocol and connection timeout are not considered.
|
|
|
|
## Using Transparent Proxy
|
|
|
|
In Kubernetes, services can reach other services via their
|
|
[KubeDNS](https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/) address or via Pod IPs, and that
|
|
traffic will be transparently sent through the proxy. Connect services in Kubernetes are required to have a Kubernetes
|
|
service selecting the Pods.
|
|
|
|
~> Note: In order to use KubeDNS, the Kubernetes service name will need to match the Consul service name. This will be the
|
|
case by default, unless the service Pods have the annotation `consul.hashicorp.com/connect-service` overriding the
|
|
Consul service name.
|
|
|
|
Transparent proxy is enabled by default in Consul-helm >=`0.32.0`. The Helm value used to enable/disable transparent
|
|
proxy for all applications in a Kubernetes cluster is `connectInject.transparentProxy.defaultEnabled`.
|
|
|
|
Each Pod for the service will be configured with iptables rules to direct all inbound and outbound traffic through an
|
|
inbound and outbound listener on the sidecar proxy. The proxy will be configured to know how to route traffic to the
|
|
appropriate upstream services based on [Service
|
|
Intentions](/docs/connect/config-entries/service-intentions). This means Connect services no longer
|
|
need to use the `consul.hashicorp.com/connect-service-upstreams` annotation to configure upstreams explicitly. Once the
|
|
Service Intentions are set, they can simply address the upstream services using KubeDNS.
|
|
|
|
As of Consul-k8s >= `0.26.0` and Consul-helm >= `0.32.0`, a Kubernetes service that selects application pods is required
|
|
for Connect applications, i.e:
|
|
|
|
```yaml
|
|
apiVersion: v1
|
|
kind: Service
|
|
metadata:
|
|
name: sample-app
|
|
namespace: default
|
|
spec:
|
|
selector:
|
|
app: sample-app
|
|
ports:
|
|
- protocol: TCP
|
|
port: 80
|
|
```
|
|
|
|
In the example above, if another service wants to reach `sample-app` via transparent proxying,
|
|
it can dial `sample-app.default.svc.cluster.local`, using
|
|
[KubeDNS](https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/).
|
|
If ACLs with default "deny" policy are enabled, it also needs a
|
|
[ServiceIntention](/docs/connect/config-entries/service-intentions) allowing it to talk to
|
|
`sample-app`.
|
|
|
|
### Headless Services
|
|
For services that are not addressed using a virtual cluster IP, the upstream service must be
|
|
configured using the [DialedDirectly](/docs/connect/config-entries/service-defaults#dialeddirectly)
|
|
option.
|
|
|
|
Individual instance addresses can then be discovered using DNS, and dialed through the transparent proxy.
|
|
When this mode is enabled on the upstream, connect certificates will be presented for mTLS and
|
|
intentions will be enforced at the destination.
|
|
|
|
Note that when dialing individual instances HTTP routing rules configured with config entries
|
|
will **not** be considered. The transparent proxy acts as a TCP proxy to the original
|
|
destination IP address.
|