Overview of vSphere Integrated Containers For DevOps Administrators

vSphere Integrated Containers integrates of all the packaging and runtime benefits of containers with the enterprise capabilities of a vSphere environment. As a DevOps admin, you use vSphere Integrated Containers Registry to manage container images and you use vSphere Integrated Containers Management Portal to deploy and managing container-based applications.

  • vSphere Integrated Containers Registry is an enterprise-class registry server that you can use to store and distribute container images. vSphere Integrated Containers Registry allows DevOps administrators to organize image repositories in projects, and to set up role-based access control to those projects to define which users can access which repositories. vSphere Integrated Containers Registry also provides rule-based replication of images between registries, implements Docker Content Trust, and provides detailed logging for project and user auditing.
  • vSphere Integrated Containers Management Portal is a highly scalable and very lightweight container management platform for deploying and managing container based applications. It is designed to have a small footprint and boot extremely quickly. vSphere Integrated Containers Management Portal is intended to provide DevOps administrators with automated deployment and lifecycle management of containers, including the following services:

    • Rule-based resource management, allowing DevOps administrators to set deployment preferences which let vSphere Integrated Containers Management Portal manage container placement.
    • Live state updates that provide a live view of the container system.
    • Multi-container template management, that enables logical multi-container application deployments.

The information in this topic is intended for DevOps administrators. For an extended version of this information, see Overview of vSphere Integrated Containers for vSphere Administrators in vSphere Integrated Containers for vSphere Administrators.

Differences Between vSphere Integrated Containers and a Classic Container Environment

The main differences between vSphere Integrated Containers and a classic container environment are the following:

  • vSphere, not Linux, is the container host:
    • Containers are spun up as VMs, not in VMs.
    • Every container is fully isolated from the host and from the other containers.
    • vSphere provides per-tenant dynamic resource limits within a vCenter Server cluster
  • vSphere, not Linux, is the infrastructure:
    • You can select vSphere networks that appear in the Docker client as container networks.
    • Images, volumes, and container state are provisioned directly to VMFS.
  • vSphere is the control plane:
    • Use the Docker client to directly control selected elements of vSphere infrastructure.
    • A container endpoint Service-as-a-Service presents as a service abstraction, not as IaaS

What Does vSphere Integrated Containers Do?

vSphere Integrated Containers allows a DevOps administrator or the vSphere administrator to easily make the vSphere infrastructure accessible to container application developers, so that you can provision container workloads into production.

Scenario 1: A Classic Container Environment

In a classic container environment:

  • A user raise a ticket and say, "I need Docker".
  • The vSphere administrator provisions a large Linux VM and sends you the IP address.
  • You install Docker, patch the OS, configure in-guest network and storage virtualization, secure the guest, isolate the containers, package the containers efficiently, and manage upgrades and downtime.

In this scenario, what the vSphere administrator has given you is similar to a nested hypervisor that you have to manage and which is opaque to them.

Scenario 2: vSphere Integrated Containers

With vSphere Integrated Containers:

  • A user raises a ticket and say, "I need Docker".
  • The vSphere administrator identifies datastores, networking, and compute on a cluster that they can use in the Docker environment.
  • The vSphere administrator uses a utility called vic-machine to install a small appliance, called a virtual container host (VCH). The VCH represents an authorization for users to use the infrastructure that the vSphere administrator has identified, into which they can self-provision container workloads.
  • The appliance runs a secure remote Docker API, that is the only access that users have to the vSphere infrastructure.
  • Instead of sending the users a Linux VM, the vSphere administrator sends them the IP address of the appliance, the port of the remote Docker API, and a certificate for secure access.

What Is vSphere Integrated Containers Engine?

The objective of vSphere Integrated Containers Engine is to take as much of vSphere as possible and layer whatever Docker capabilities are missing on top, reusing as much of Docker’s own code as possible. The result should not sacrifice the portability of the Docker image format and should be completely transparent to a Docker client. The following sections describe key concepts and components that make this possible.

Container VMs

The container VMs that vSphere Integrated Containers Engine creates have all of the characteristics of software containers:

  • An ephemeral storage layer with optionally attached persistent volumes.
  • A custom Linux guest OS that is designed to be "just a kernel" and that needs images to be functional.
  • A mechanism for persisting and attaching read-only binary image layers.
  • A PID 1 guest agent tether extends the control plane into the container VM.
  • Various well-defined methods of configuration and state ingress and egress
  • Automatically configured to various network topologies.

The provisioned container VM does not contain any OS container abstraction.

  • The container VM boots from an ISO that contains the Photon Linux kernel. Note that container VMs do not run the full Photon OS.
  • The container VM is configured with a container image that is mounted as a disk.
  • Container image layers are represented as a read-only VMDK snapshot hierarchy on a vSphere datastore. At the top of this hierarchy is a read-write snapshot that stores ephemeral state.
  • Container volumes are formatted VMDKs that are attached as disks and indexed on a datastore.
  • Networks are distributed port groups that are attached as vNICs.

Virtual Container Hosts

A virtual container host (VCH) is the functional equivalent of a Linux VM that runs Docker, but with some significant benefits. A VCH represents the following elements:

  • A clustered pool of resource into which to provision container VMs.
  • A single-tenant container namespace.
  • A secure API endpoint.
  • Authorization to use and configure pre-approved virtual infrastructure.

A VCH is functionally distinct from a traditional container host in the following ways:

  • It naturally encapsulates clustering and dynamic scheduling by provisioning to vSphere targets.
  • The resource constraints are dynamically configurable with no impact on the containers.
  • Containers do not share a kernel.
  • There is no local image cache. This is kept on a datastore in the cluster that the vSphere administrator specified when they deployed a VCH.
  • There is no read-write shared storage

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