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In order to automatically intercept traffic from and to a service through a
kuma-dp data plane proxy instance, Kuma utilizes a transparent proxying using
Transparent proxying helps with a smoother rollout of a Service Mesh to a current deployment by preserving existing service naming and as the result - avoid changes to the application code.
kuma-dp leverages transparent proxying automatically via
iptables installed with
kuma-init container or CNI.
All incoming and outgoing traffic is automatically intercepted by
kuma-dp without having to change the application code.
Kuma integrates with a service naming provided by Kubernetes DNS as well as providing its own Kuma DNS for multizone service naming.
kuma-dp leverages the data plane proxy specification associated to it for receiving incoming requests on a pre-defined port.
There are several advantages for using transparent proxying in universal mode:
- Simpler Dataplane resource, as the
outboundsection becomes obsolete and can be skipped.
- Universal service naming with
.meshDNS domain instead of explicit outbound like
- Support for hostnames of your choice using VirtualOutbounds that lets you preserve existing service naming.
- Better service manageability (security, tracing).
Setting up the service host
corednsmust run on the worker node – that is, the node that runs your service mesh workload.
corednsmust be in the PATH so that
kuma-dpcan access it.
- You can also set the location with the
- You can also set the location with the
Kuma comes with
kumactl executable which can help us to prepare the host. Due to the wide variety of Linux setup options, these steps may vary and may need to be adjusted for the specifics of the particular deployment.
The host that will run the
kuma-dp process in transparent proxying mode needs to be prepared with the following steps executed as
- Create a new dedicated user on the machine.
useradd -u 5678 -U kuma-dp
- Redirect all the relevant inbound, outbound and DNS traffic to the Kuma data plane proxy.
kumactl install transparent-proxy \ --kuma-dp-user kuma-dp \ --skip-resolv-conf \ --redirect-dns
Please note that this command will change the host
The changes will persist over restarts, so this command is needed only once. Reverting to the original state of the host can be done by issuing
kumactl uninstall transparent-proxy.
Data plane proxy resource
In transparent proxying mode, the
Dataplane resource should omit the
networking.outbound section and use
networking.transparentProxying section instead.
type: Dataplane mesh: default name: networking: address: inbound: - port: tags: kuma.io/service: demo-client transparentProxying: redirectPortInbound: 15006 redirectPortOutbound: 15001
The ports illustrated above are the default ones that
kumactl install transparent-proxy will set. These can be changed using the relevant flags to that command.
Invoking the Kuma data plane
It is important that the
kuma-dp process runs with the same system user that was passed to
kumactl install transparent-proxy --kuma-dp-user.
When systemd is used, this can be done with an entry
User=kuma-dp in the
[Service] section of the service file.
kuma-dp with a script or some other automation instead, we can use
runuser with the aforementioned yaml resource as follows:
runuser -u kuma-dp -- \ /usr/bin/kuma-dp run \ --cp-address=https://<IP or hostname of CP>:5678 \ --dataplane-token-file=/kuma/token-demo \ --dataplane-file=/kuma/dpyaml-demo \ --dataplane-var name=dp-demo \ --dataplane-var address=<IP of VM> \ --dataplane-var port=<Port of the service> \ --binary-path /usr/local/bin/envoy
You can now reach the service on the same IP and port as before installing transparent proxy, but now the traffic goes through Envoy. At the same time, you can now connect to services using Kuma DNS.
If you run
firewalld to manage firewalls and wrap iptables, add the
--store-firewalld flag to
kumactl install transparent-proxy. This persists the relevant rules across host restarts. The changes are stored in
/etc/firewalld/direct.xml. There is no uninstall command for this feature.
Before upgrading to the next version of Kuma, make sure to run
kumactl uninstall transparent-proxy and only then replace the
This will ensure smooth upgrade and no leftovers from the previous installations.
By default, all the traffic is intercepted by Envoy. You can exclude which ports are intercepted by Envoy with the following annotations placed on the Pod
apiVersion: apps/v1 kind: Deployment metadata: name: example-app namespace: kuma-example spec: ... template: metadata: ... annotations: # all incomming connections on ports 1234 won't be intercepted by Envoy traffic.kuma.io/exclude-inbound-ports: "1234" # all outgoing connections on ports 5678, 8900 won't be intercepted by Envoy traffic.kuma.io/exclude-outbound-ports: "5678,8900" spec: containers: ...
You can also control this value on whole Kuma deployment with the following Kuma CP configuration
By default, every data plane proxy in the mesh follows every other data plane proxy. This may lead to performance problems in larger deployments of the mesh. It is highly recommended to define a list of services that your service connects to.
apiVersion: apps/v1 kind: Deployment metadata: name: example-app namespace: kuma-example spec: ... template: metadata: ... annotations: # a comma separated list of kuma.io/service values kuma.io/transparent-proxying-reachable-services: "redis_kuma-demo_svc_6379,elastic_kuma-demo_svc_9200" spec: containers: ...