mirror of https://github.com/status-im/consul.git
151 lines
7.0 KiB
Plaintext
151 lines
7.0 KiB
Plaintext
---
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layout: docs
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page_title: Join External Services to Consul on Kubernetes
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description: >-
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Services running on a virtual machine (VM) can join a Consul datacenter running on Kubernetes. Learn how to configure the Kubernetes installation to accept communication from external services.
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---
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# Join External Services to Consul on Kubernetes
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Services running on non-Kubernetes nodes can join a Consul cluster running within Kubernetes.
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## Auto-join
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The recommended way to join a cluster running within Kubernetes is to
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use the ["k8s" cloud auto-join provider](/consul/docs/install/cloud-auto-join#kubernetes-k8s).
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The auto-join provider dynamically discovers IP addresses to join using
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the Kubernetes API. It authenticates with Kubernetes using a standard
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`kubeconfig` file. Auto-join works with all major hosted Kubernetes offerings
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as well as self-hosted installations. The token in the `kubeconfig` file
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needs to have permissions to list pods in the namespace where Consul servers
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are deployed.
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The auto-join string below joins a Consul server agent to a cluster using the [official Helm chart](/consul/docs/k8s/helm):
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```shell-session
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$ consul agent -retry-join 'provider=k8s label_selector="app=consul,component=server"'
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```
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-> **Note:** This auto-join command only connects on the default gossip port
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8301, whether you are joining on the pod network or via host ports. A
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Consul server that is already a member of the datacenter should be
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listening on this port for the external service to connect through
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auto-join.
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### Auto-join on the Pod network
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In the default Consul Helm chart installation, Consul servers are
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routable through their pod IPs for server RPCs. As a result, any
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external agents joining the Consul cluster running on Kubernetes
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need to be able to connect to those pod IPs.
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In many hosted Kubernetes environments, you need to explicitly configure
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your hosting provider to ensure that pod IPs are routable from external VMs.
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For more information, refer to [Azure AKS CNI](https://docs.microsoft.com/en-us/azure/aks/concepts-network#azure-cni-advanced-networking),
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[AWS EKS CNI](https://docs.aws.amazon.com/eks/latest/userguide/pod-networking.html) and
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[GKE VPC-native clusters](https://cloud.google.com/kubernetes-engine/docs/concepts/alias-ips).
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To join external agents with Consul on Kubernetes deployments installed with default values through the [official Helm chart](/consul/docs/k8s/helm):
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1. Make sure the pod IPs of the servers in Kubernetes are
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routable from the VM and that the VM can access port 8301 (for gossip) and
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port 8300 (for server RPC) on those pod IPs.
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1. Make sure that the server pods running in Kubernetes can route
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to the VM's advertise IP on its gossip port (default 8301).
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1. Make sure you have the `kubeconfig` file for the Kubernetes cluster in `$HOME/.kube/config` on the external VM.
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1. On the external VM, run:
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```shell-session
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consul agent \
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-advertise="$ADVERTISE_IP" \
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-retry-join='provider=k8s label_selector="app=consul,component=server"' \
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-bind=0.0.0.0 \
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-hcl='leave_on_terminate = true' \
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-hcl='ports { grpc = 8502 }' \
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-config-dir=$CONFIG_DIR \
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-datacenter=$DATACENTER \
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-data-dir=$DATA_DIR \
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```
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1. Run `consul members` to check if the join was successful.
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```shell-session
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/ $ consul members
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Node Address Status Type Build Protocol DC Segment
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consul-consul-server-0 10.138.0.43:9301 alive server 1.9.1 2 dc1 <all>
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external-agent 10.138.0.38:8301 alive client 1.9.0 2 dc1 <default>
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gke-external-agent-default-pool-32d15192-grs4 10.138.0.43:8301 alive client 1.9.1 2 dc1 <default>
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gke-external-agent-default-pool-32d15192-otge 10.138.0.44:8301 alive client 1.9.1 2 dc1 <default>
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gke-external-agent-default-pool-32d15192-vo7k 10.138.0.42:8301 alive client 1.9.1 2 dc1 <default>
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```
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### Auto-join through host ports
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If your external VMs cannot connect to Kubernetes pod IPs but they can connect
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to the internal host IPs of the nodes in the Kubernetes cluster, you can join the two by exposing ports on the host IP instead.
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1. Install the [official Helm chart](/consul/docs/k8s/helm) with the following values:
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```yaml
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client:
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exposeGossipPorts: true # exposes client gossip ports as hostPorts
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server:
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exposeGossipAndRPCPorts: true # exposes the server gossip and RPC ports as hostPorts
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ports:
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# Configures the server gossip port
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serflan:
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# Note that this needs to be different than 8301, to avoid conflicting with the client gossip hostPort
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port: 9301
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```
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This installation exposes the client gossip ports, the server gossip ports and the server RPC port at `hostIP:hostPort`. Note that `hostIP` is the **internal** IP of the VM that the client/server pods are deployed on.
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1. Make sure the IPs of the Kubernetes nodes are routable from the VM and
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that the VM can access ports 8301 and 9301 (for gossip) and port 8300 (for
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server RPC) on those node IPs.
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1. Make sure the server pods running in Kubernetes can route to
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the VM's advertise IP on its gossip port (default 8301).
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1. Make sure you have the `kubeconfig` file for the Kubernetes cluster in `$HOME/.kube/config` on the external VM.
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1. On the external VM, run:
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```shell-session
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consul agent \
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-advertise="$ADVERTISE_IP" \
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-retry-join='provider=k8s host_network=true label_selector="app=consul,component=server"'
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-bind=0.0.0.0 \
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-hcl='leave_on_terminate = true' \
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-hcl='ports { grpc = 8502 }' \
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-config-dir=$CONFIG_DIR \
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-datacenter=$DATACENTER \
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-data-dir=$DATA_DIR \
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```
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Note the addition of `host_network=true` in the retry-join argument.
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1. Run `consul members` to check if the join was successful.
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```shell-session
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/ $ consul members
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Node Address Status Type Build Protocol DC Segment
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consul-consul-server-0 10.138.0.43:9301 alive server 1.9.1 2 dc1 <all>
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external-agent 10.138.0.38:8301 alive client 1.9.0 2 dc1 <default>
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gke-external-agent-default-pool-32d15192-grs4 10.138.0.43:8301 alive client 1.9.1 2 dc1 <default>
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gke-external-agent-default-pool-32d15192-otge 10.138.0.44:8301 alive client 1.9.1 2 dc1 <default>
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gke-external-agent-default-pool-32d15192-vo7k 10.138.0.42:8301 alive client 1.9.1 2 dc1 <default>
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```
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## Manual join
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If you are unable to use auto-join, try following the instructions in
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either of the auto-join sections, but instead of using a `provider` key in the
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`-retry-join` flag, pass the address of at least one Consul server. Example: `-retry-join=$CONSUL_SERVER_IP:$SERVER_SERFLAN_PORT`.
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A `kubeconfig` file is not required when using manual join.
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Instead of hardcoding an IP address, we recommend you set up a DNS entry
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that resolves to the pod IPs or host IPs that the Consul server pods are running on. |