Sonny

Sonny is a project providing automatic recovery for OpenStack instances from compute nodes that experience hardware failure. It takes care that your pet instances become available when inevitable hardware failure happens. Sonny only works with CEPH being used as a beckend for emphemeral disks and Cinder volumes.

Motivation

Modern applications in a cloud environment follow "cattle" model where application is build in a resilient way to tolerate the case where the instance dies for some reason. Maybe you haven't managed to get to the point where you have this kind of application and you are still treating virtual machines as a pets. That means that you want to have your pet resurrected when inevitable hardware failure kills it. Sonny brings you support for this scenario.

Arhitecture

Project provides 3 separate processes that communicate with each other by redis, using RQ. Process ns4 serves as a worker process, monitor has the logic for detecting if hypervisor is dead by delegating jobs to ns4. It communicates important events to sonny which serves as middle "man" to carry this information to Slack. It is also able to respond to some basic information questions about virtual instances and hypervisors.

Processes

• ns4 has jobs defined for updating OpenStack inventory (hosts, projects, neutron agents and instances) in redis, job for performing tcp scan on a list of hosts and last but not least, job for resurrecting dead instances from a dead hypervisor.

• monitor gives all the work to ns4 but carries the core logic. It updates redis inventory, checks for hypervisors who's neutron agents haven't sent heartbeat in the last minute and performs tcp check on ports 22, 111 and 16509. If there is no reponse, it does tcp check on port 22 on all the instances that have IP from external network. In case there is no response, it concludes the hypervisor is dead and starts resurrecting all the instances.

• sonny subscribes to redis channels for messages from monitors. It post this messages on predefined Slack channel. It has very limited capabilities to responding to some questions.

Constraints and limitiations

List of assumptions, constraints and limitations:

• all monitors are using the same redis host but each monitor has different database,
• ns4 is able to reach all hypervisors on tcp 22, 111 and 16509,
• any hypervisor has at least one instance that ns4 can rach on tcp port 22.

Getting Started

Prerequisites

Supported OpenStack enviornment is using KVM based hardware virtualization and CEPH storage backend for emphemeral disks and Cinder volumes.

Install nmap and redis and use python 3.7.

Installing

Build and Install

virtualenv ~/.venv-sonny
source ~/.venv-sonny/bin/activate

git clone https://github.com/marko-k0/sonny
cd sonny
pip install .

Configuration

Configure Slack Bot User and OpenStack clouds.yaml. Create ~/.config.ini and set configuration parameters for REDIS, MYSQL, OPENSTACK and SLACK.

Configuration under DEFAULT section has the following meaning:

• monitor_period defines the period that the monitor does the check,
• hearbeat_period is the period by which all the neutron agents should be reporting to controller,
• suspicious_backoff defines how many hypervisors monitor can still inspect when heartbeats from neutron agents are missing,
• cooldown_period is the period that the monitor doesn't perform any action after resurrection happens,
• dead_backoff is the maximum number of dead hypervisors that monitor will be willing to handle.

Run

cd ~
tmux new-session -s sonny
tmux new-window -n ns4 ns4 -v
tmux new-window -n sonny sonny
tmux new-window -n monitor monitor -v

Comparison to Masakari

OpenStack project Masakari exists that provides similar service. TODO

TODO

• Beta version.
• Dockerize.
• HA version.
• Chatbot.

License

This project is currently licensed under GPLv3 - see LICENSE.txt file.