121 lines
4.0 KiB
ReStructuredText
121 lines
4.0 KiB
ReStructuredText
======================================
|
|
How-To expose a service outside of K8S
|
|
======================================
|
|
|
|
++++++++
|
|
Overview
|
|
++++++++
|
|
|
|
When Juju deploys an Operator Charm to Kubernetes by default a
|
|
ClusterIP service entry is created for each application to provide
|
|
resilient, load balanced access to the services it provides from
|
|
within the Kubernetes deployment.
|
|
|
|
For the majority of OpenStack API services external ingress access
|
|
is required to the API endpoints from outside of Kubernetes - this
|
|
is used by both end-users of the cloud as well as from machine
|
|
based charms supporting OpenStack Hypervisors.
|
|
|
|
Operator charms for API or other web services written using Sunbeam
|
|
OpenStack will automatically patch the Juju created service entry to
|
|
be of type LoadBalancer, enabling Kubernetes to expose the service to
|
|
the outside world using a suitable Load Balancer implementation.
|
|
|
|
++++++++
|
|
MicroK8S
|
|
++++++++
|
|
|
|
For a MicroK8S deployment on bare metal MetalLB can be enabled to
|
|
support this feature:
|
|
|
|
.. code-block:: none
|
|
|
|
microk8s enable metallb
|
|
|
|
by default Microk8s will prompt for an IP address pool for MetalLB
|
|
to use - this can also be provided in the enable command:
|
|
|
|
.. code-block:: none
|
|
|
|
microk8s enable metallb:10.64.140.43-10.64.140.49
|
|
|
|
Please refer to the `MicroK8S MetalLB add-on`_ documentation for more
|
|
details.
|
|
|
|
++++++++++++++++++
|
|
Charmed Kubernetes
|
|
++++++++++++++++++
|
|
|
|
For a Charmed Kubernetes deployment on bare metal MetalLB can also be
|
|
used for creation of LoadBalancer access to services.
|
|
|
|
`Operator Charms for MetalLB`_ exist but don't yet support BGP mode for
|
|
ECMP (Equal Cost Multi Path) based load balancing by integrating directly
|
|
into the network infrastructure hosting the Kubernetes deployment.
|
|
|
|
For this reason its recommended to use the upstream manifests for
|
|
deployment of MetalLB with a suitable ConfigMap for the BGP network
|
|
configuration or Layer 2 configuration depending on the mode of
|
|
operation desired:
|
|
|
|
.. code-block:: none
|
|
|
|
kubectl apply -f https://raw.githubusercontent.com/metallb/metallb/v0.9.3/manifests/namespace.yaml
|
|
kubectl apply -f https://raw.githubusercontent.com/metallb/metallb/v0.9.3/manifests/metallb.yaml
|
|
# On first install only
|
|
kubectl create secret generic -n metallb-system memberlist --from-literal=secretkey="$(openssl rand -base64 128)"
|
|
|
|
Example ConfigMap for configuration of MetalLB in BGP mode:
|
|
|
|
.. code-block:: yaml
|
|
|
|
apiVersion: v1
|
|
kind: ConfigMap
|
|
metadata:
|
|
namespace: metallb-system
|
|
name: config
|
|
data:
|
|
config: |
|
|
peers:
|
|
- peer-address: 10.0.0.1
|
|
peer-asn: 64512
|
|
my-asn: 64512
|
|
address-pools:
|
|
- name: default
|
|
protocol: bgp
|
|
addresses:
|
|
- 10.64.140.43-10.64.140.49
|
|
|
|
IP address pools and BGP peer configuration will be entirely
|
|
deployment specific.
|
|
|
|
++++++++++++++
|
|
Service Access
|
|
++++++++++++++
|
|
|
|
Once MetalLB has created a LoadBalancer configuration for a service its
|
|
external IP address will be populated in the service entry. Juju will
|
|
automatically pick this address for use as the ingress address for the
|
|
service on relations (which is not ideal for service communication
|
|
within the Kubernetes deployment)
|
|
|
|
The IP address can also be discovered using the juju status command -
|
|
the Load Balancer external IP will be detailed in the application
|
|
information:
|
|
|
|
.. code-block:: none
|
|
|
|
$ juju status cinder
|
|
Model Controller Cloud/Region Version SLA Timestamp
|
|
sunbeam maas-one k8s-cloud/default 2.9.22 unsupported 11:21:51Z
|
|
|
|
App Version Status Scale Charm Store Channel Rev OS Address Message
|
|
cinder waiting 1 sunbeam-cinder-operator local 0 kubernetes 10.0.0.40 installing agent
|
|
|
|
Unit Workload Agent Address Ports Message
|
|
cinder/0* unknown idle 10.1.73.176
|
|
|
|
.. LINKS
|
|
.. _MicroK8S MetalLB add-on: https://microk8s.io/docs/addon-metallba
|
|
.. _Operator Charms for MetalLB: https://ubuntu.com/kubernetes/docs/metallb
|