- Docker Hypervisor.framework
- Docker Virtualization Error
- Hyper V - Using Docker With Hypervisor Instead Of Wsl2 ...
- Acrn Hypervisor Docker
- 4. Introduction To Hypervisor , Docker & Container - Virtual Machines (VM)
- Citrix Hypervisor With Docker - Citrix
The nova-docker project described here is unmaintained and has been retired. Please see the documentation on the Zun service for an alternative solution.
- 1Overview
- 2Configure an existing OpenStack installation to enable Docker
- 3Configure DevStack to use Nova-Docker
Watch the complete course at: the subscrib. Hardware virtualization, like VMware, and process virtualization through containers, like Docker, offer competing methods for virtualizing applications. Both technologies work to make the most of limited hardware resources, but they do so in significantly different ways. In this guide, we will help you understand how they differ and how those.
Overview
The Docker driver is a hypervisor driver for Openstack Nova Compute. It was introduced with the Havana release, but lives out-of-tree for Icehouse and Juno. Being out-of-tree has allowed the driver to reach maturity and feature-parity faster than would be possible should it have remained in-tree. It is expected the driver will return to mainline Nova in the Kilo release.
Docker is an open-source engine which automates the deployment of applications as highly portable, self-sufficient containers which are independent of hardware, language, framework, packaging system and hosting provider.
Docker provides management of Linux containers with a high level API providing a lightweight solution that runs processes in isolation. It provides a way to automate software deployment in a secure and repeatable environment. A Docker container includes a software component along with all of its dependencies - binaries, libraries, configuration files, scripts, virtualenvs, jars, gems, tarballs, etc. Docker can be run on any x64 Linux kernel supporting cgroups and aufs.
Docker is a way of managing multiple containers on a single machine. However used behind Nova makes it much more powerful since it’s then possible to manage several hosts, which in turn manage hundreds of containers. The current Docker project aims for full OpenStack compatibility.
Containers don't aim to be a replacement for VMs, they are complementary in the sense that they are better for specific use cases.
What unique advantages Docker bring over other containers technologies?
Docker takes advantage of containers and filesystem technologies in a high-level which are not generic enough to be managed by libvirt.
- Process-level API: Docker can collect the standard outputs and inputs of the process running in each container for logging or direct interaction, it allows blocking on a container until it exits, setting its environment, and other process-oriented primitives which don’t fit well in libvirt’s abstraction.
- Advanced change control at the filesystem level: Every change made on the filesystem is managed through a set of layers which can be snapshotted, rolled back, diff-ed etc.
- Image portability: The state of any docker container can be optionally committed as an image and shared through a central image registry. Docker images are designed to be portable across infrastructures, so they are a great building block for hybrid cloud scenarios.
- Build facility: docker can automate the assembly of a container from an application’s source code. This gives developers an easy way to deploy payloads to an OpenStack cluster as part of their development workflow.
How does the Nova hypervisor work under the hood?
The Nova driver embeds a tiny HTTP client which talks with the Docker internal Rest API through a unix socket. It uses the HTTP API to control containers and fetch information about them.
The driver will fetch images from the OpenStack Image Service (Glance) and load them into the Docker filesystem. Images may be placed in Glance by exporting them from Docker using the 'docker save' command.
Older versions of this driver required running a private docker-registry, which would proxy to Glance. This is no longer required.
Configure an existing OpenStack installation to enable Docker
Installing Docker for OpenStack
The first requirement is to install Docker on your compute hosts.
In order for Nova to communicate with Docker over its local socket, add nova to the docker group and restart the compute service to pick up the change:
You will also need to install the driver:
You should then install the required modules
You may optionally choose to create operating-system packages for this, or use another appropriate installation method for your deployment.
Nova configuration
Nova needs to be configured to use the Docker virt driver.
Edit the configuration file /etc/nova/nova.conf according to the following options:
Docker Hypervisor.framework
Create the directory /etc/nova/rootwrap.d, if it does not already exist, and inside that directory create a file 'docker.filters' with the following content:
Glance configuration
Glance needs to be configured to support the 'docker' container format. It's important to leave the default ones in order to not break an existing glance install.
Using Nova-Docker
Once you configured Nova to use the docker driver, the flow is the same as anyother driver.
Only images with a 'docker' container format will be bootable. The image contains basically a tarball of the container filesystem.
It's recommended to add new images to Glance by using Docker. For instance, here is how you can fetch images from the public registry and push them back to Glance in order to boot a Nova instance with it:
Then, pull the image and push it to Glance:
NOTE: The name you provide to glance must match the name by which the image is known to docker.
You can obviously boot instances from nova cli:
Once the instance is booted:
You can also see the corresponding container on docker:
The command used here is the one configured in the image. Each container image can have a command configured for the run. The driver does not usually override this. You can image booting an apache2 instance, it will start the apache process if the image is authored properly via a Dockerfile.
Configure DevStack to use Nova-Docker
Using the Docker hypervisor via DevStack replaces all manual configuration needed above.
Note: below, localadmin admin user, adjust to suit your configuration
Install the latest Docker release
Ubuntu:
Fedora:
Prepare Nova-Docker
Set up Devstack
Clone devstack (it is recommended to use the same releases of devstack and nova-docker, e.g., stable/kilo, master, etc.)
Before running DevStack's stack.sh script, configure the following options in the local.conf or localrc file:
Configure nova to use the nova-docker driverNote: neutron is the default as of kilo
Start Devstack
Docker Virtualization Error
./stack.sh
Testing Nova-Docker
Copy the filters
Start a Container
Assign it a floating IP and connect to it
Configure DevStack to use Nova-Docker (alternate post-stack method)
Using the Docker hypervisor via DevStack replaces all manual configuration needed above.
Install Docker, then install Devstack and run stack.sh
Once stack.sh completes, run unstack.sh from the devstack directory
Hyper V - Using Docker With Hypervisor Instead Of Wsl2 ...
Install nova-docker:
Prepare DevStack:
Run stack.sh from devstack directory:
Acrn Hypervisor Docker
It may be necessary to install a Docker filter as well:
Resources
- Lars Kellogg-Stedman; Installing Nova-Docker with Devstack (blog post)
Community
We have a Nova Subteam and involvement of various contributors may be verified via Github's contributors page.
Docker is an open-source engine which automates the deployment of applications as highly portable, self-sufficient containers which are independent of hardware, language, framework, packaging system and hosting provider.
Docker provides management of Linux containers with a high level API providing a lightweight solution that runs processes in isolation. It provides a way to automate software deployment in a secure and repeatable environment. A Docker container includes a software component along with all of its dependencies - binaries, libraries, configuration files, scripts, virtualenvs, jars, gems, tarballs, etc. Docker can be run on any x64 Linux kernel supporting cgroups and aufs.
Docker is a way of managing multiple containers on a single machine. However used behind Nova makes it much more powerful since it’s then possible to manage several hosts, which in turn manage hundreds of containers. The current Docker project aims for full OpenStack compatibility.
Containers don't aim to be a replacement for VMs, they are complementary in the sense that they are better for specific use cases.
What unique advantages Docker bring over other containers technologies?
Docker takes advantage of containers and filesystem technologies in a high-level which are not generic enough to be managed by libvirt.
- Process-level API: Docker can collect the standard outputs and inputs of the process running in each container for logging or direct interaction, it allows blocking on a container until it exits, setting its environment, and other process-oriented primitives which don’t fit well in libvirt’s abstraction.
- Advanced change control at the filesystem level: Every change made on the filesystem is managed through a set of layers which can be snapshotted, rolled back, diff-ed etc.
- Image portability: The state of any docker container can be optionally committed as an image and shared through a central image registry. Docker images are designed to be portable across infrastructures, so they are a great building block for hybrid cloud scenarios.
- Build facility: docker can automate the assembly of a container from an application’s source code. This gives developers an easy way to deploy payloads to an OpenStack cluster as part of their development workflow.
How does the Nova hypervisor work under the hood?
The Nova driver embeds a tiny HTTP client which talks with the Docker internal Rest API through a unix socket. It uses the HTTP API to control containers and fetch information about them.
The driver will fetch images from the OpenStack Image Service (Glance) and load them into the Docker filesystem. Images may be placed in Glance by exporting them from Docker using the 'docker save' command.
Older versions of this driver required running a private docker-registry, which would proxy to Glance. This is no longer required.
Configure an existing OpenStack installation to enable Docker
Installing Docker for OpenStack
The first requirement is to install Docker on your compute hosts.
In order for Nova to communicate with Docker over its local socket, add nova to the docker group and restart the compute service to pick up the change:
You will also need to install the driver:
You should then install the required modules
You may optionally choose to create operating-system packages for this, or use another appropriate installation method for your deployment.
Nova configuration
Nova needs to be configured to use the Docker virt driver.
Edit the configuration file /etc/nova/nova.conf according to the following options:
Docker Hypervisor.framework
Create the directory /etc/nova/rootwrap.d, if it does not already exist, and inside that directory create a file 'docker.filters' with the following content:
Glance configuration
Glance needs to be configured to support the 'docker' container format. It's important to leave the default ones in order to not break an existing glance install.
Using Nova-Docker
Once you configured Nova to use the docker driver, the flow is the same as anyother driver.
Only images with a 'docker' container format will be bootable. The image contains basically a tarball of the container filesystem.
It's recommended to add new images to Glance by using Docker. For instance, here is how you can fetch images from the public registry and push them back to Glance in order to boot a Nova instance with it:
Then, pull the image and push it to Glance:
NOTE: The name you provide to glance must match the name by which the image is known to docker.
You can obviously boot instances from nova cli:
Once the instance is booted:
You can also see the corresponding container on docker:
The command used here is the one configured in the image. Each container image can have a command configured for the run. The driver does not usually override this. You can image booting an apache2 instance, it will start the apache process if the image is authored properly via a Dockerfile.
Configure DevStack to use Nova-Docker
Using the Docker hypervisor via DevStack replaces all manual configuration needed above.
Note: below, localadmin admin user, adjust to suit your configuration
Install the latest Docker release
Ubuntu:
Fedora:
Prepare Nova-Docker
Set up Devstack
Clone devstack (it is recommended to use the same releases of devstack and nova-docker, e.g., stable/kilo, master, etc.)
Before running DevStack's stack.sh script, configure the following options in the local.conf or localrc file:
Configure nova to use the nova-docker driverNote: neutron is the default as of kilo
Start Devstack
Docker Virtualization Error
./stack.sh
Testing Nova-Docker
Copy the filters
Start a Container
Assign it a floating IP and connect to it
Configure DevStack to use Nova-Docker (alternate post-stack method)
Using the Docker hypervisor via DevStack replaces all manual configuration needed above.
Install Docker, then install Devstack and run stack.sh
Once stack.sh completes, run unstack.sh from the devstack directory
Hyper V - Using Docker With Hypervisor Instead Of Wsl2 ...
Install nova-docker:
Prepare DevStack:
Run stack.sh from devstack directory:
Acrn Hypervisor Docker
It may be necessary to install a Docker filter as well:
Resources
- Lars Kellogg-Stedman; Installing Nova-Docker with Devstack (blog post)
Community
We have a Nova Subteam and involvement of various contributors may be verified via Github's contributors page.
The Docker team is also involved with the more generic and highly-overlapping efforts of the Nova Containers Sub-team.
4. Introduction To Hypervisor , Docker & Container - Virtual Machines (VM)
We are available on IRC on Freenode in #nova-docker. The containers team may be found in #openstack-containers.
Citrix Hypervisor With Docker - Citrix
