As discussed here: https://microsoft.github.io/iotedge-k8s-doc/introduction.html Kubernetes is the HA solution for Azure IoT Edge which is in preview.
Kubernetes can be challenging, especially if you have never used it before. If that is the case, then you are in luck. With 1 command (after you have an IoT Edge Connection String), you can now deploy Kubernetes on a development machine and get IoT Edge running. Intrigued? Try this an an Ubuntu 18.04 host:
wget -q -O - https://raw.githubusercontent.com/ksaye/AzureIoTEdgeOnKubernetes/master/singleHost.sh | sudo krbuser=$USER constr='HostName=kevinsayIoT.azure-devices.net;DeviceId=kubernetes;SharedAccessKey=qpRl3REMOVEDWKCgTA=' bash
(replacing this section with your connection string)
After just a few minutes, you will see this screen, indicating that both IoT Edge Agent and IoT Hub are running in the iotedge namespace.