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Support for Amazon VPC APIs on Contrail OpenStack

 

Overview of Amazon Virtual Private Cloud

The current Grizzly release of OpenStack supports Elastic Compute Cloud (EC2) API translation to OpenStack Nova, Quantum, and Keystone calls. EC2 APIs are used in Amazon Web Services (AWS) and virtual private clouds (VPCs) to launch virtual machines, assign IP addresses to virtual machines, and so on. A VPC provides a container where applications can be launched and resources can be accessed over the networking services provided by the VPC.

Contrail enhances its use of EC2 APIs to support the Amazon VPC APIs.

The Amazon VPC supports networking constructs such as: subnets, DHCP options, elastic IP addresses, network ACLs, security groups, and route tables. The Amazon VPC APIs are now supported on the Openstack Contrail distribution, so users of the Amazon EC2 APIs for their VPC can use the same scripts to move to an Openstack Contrail solution.

Euca2ools are command-line tools for interacting with Amazon Web Services (AWS) and other AWS-compatible web services, such as OpenStack. Euca2ools have been extended in OpenStack Contrail to add support for the Amazon VPC, similar to the support that already exists for the Amazon EC2 CLI.

For more information about Amazon VPC and AWS EC2, see:

Mapping Amazon VPC Features to OpenStack Contrail Features

The following table compares Amazon VPC features to their equivalent features in OpenStack Contrail.

Table 1: Amazon VPC and OpenStack Contrail Feature Comparison

Amazon VPC Feature

OpenStack Contrail Feature

VPC

Project

Subnets

Networks (Virtual Networks)

DHCP options

IPAM

Elastic IP

Floating IP

Network ACLs

Network ACLs

Security Groups

Security Groups

Route Table

Route Table

VPC and Subnets Example

When creating a new VPC, the user must provide a classless inter-domain routing (CIDR) block of which all subnets in this VPC will be part.

In the following example, a VPC is created with a CIDR block of 10.1.0.0/16. A subnet is created within the VPC CIDR block, with a CIDR block of 10.1.1.0/24. The VPC has a default network ACL named acl-default.

All subnets created in the VPC are automatically associated to the default network ACL. This association can be changed when a new network ACL is created. The last command in the list below creates a virtual machine using the image ami-00000003 and launches with an interface in subnet-5eb34ed2.

Euca2ools CLI for VPC and Subnets

The following euca2ools CLI commands are used to create, define, and delete VPCs and subnets:

  • euca-create-vpc

  • euca-delete-vpc

  • euca-describe-vpcs

  • euca-create-subnet

  • euca-delete-subnet

  • euca-describe-subnets

Security in VPC: Network ACLs Example

Network ACLs support ingress and egress rules for traffic classification and filtering. The network ACLs are applied at a subnet level.

In the following example, a new ACL, acl-ba7158, is created and an existing subnet is associated to the new ACL.

Euca2ools CLI for Network ACLs

The following euca2ools CLI commands are used to create, define, and delete VPCs and subnets:

  • euca-create-network-acl

  • euca-delete-network-acl

  • euca-replace-network-acl-association

  • euca-describe-network-acls

  • euca-create-network-acl-entry

  • euca-delete-network-acl-entry

  • euca-replace-network-acl-entry

Security in VPC: Security Groups Example

Security groups provide virtual machine level ingress/egress controls. Security groups are applied to virtual machine interfaces.

In the following example, a new security group is created. The rules can be added or removed for the security group based on the commands listed for euca2ools. The last line launches a virtual machine using the newly created security group.

Euca2ools CLI for Security Groups

The following euca2ools CLI commands are used to create, define, and delete security groups:

  • euca-create-security-group

  • euca-delete-security-group

  • euca-describe-security-groups

  • euca-authorize-security-group-egress

  • euca-authorize-security-group-ingress

  • euca-revoke-security-group-egress

  • euca-revoke-security-group-ingress

Elastic IPs in VPC

Elastic IPs in VPCs are equivalent to the floating IPs in the Contrail Openstack solution.

In the following example, a floating IP is requested from the system and assigned to a particular virtual machine. The prerequisite is that the provider or Contrail administrator has provisioned a network named “public” and allocated a floating IP pool to it. This “public” floating IP pool is then internally used by the tenants to request public IP addresses that they can use and attach to virtual machines.

Euca2ools CLI for Elastic IPs

The following euca2ools CLI commands are used to create, define, and delete elastic IPs:

  • euca-allocate-address

  • euca-release-address

  • euca-describe-addresses

  • euca-associate-address

  • euca-disassociate-address

Euca2ools CLI for Route Tables

Route tables can be created in an Amazon VPC and associated with subnets. Traffic exiting a subnet is then looked up in the route table and, based on the route lookup result, the next hop is chosen.

The following euca2ools CLI commands are used to create, define, and delete route tables:

  • euca-create-route-table

  • euca-delete-route-table

  • euca-describe-route-tables

  • euca-associate-route-table

  • euca-disassociate-route-table

  • euca-replace-route-table-association

  • euca-create-route

  • euca-delete-route

  • euca-replace-route

Supported Next Hops

The supported next hops are:

  • Local Next Hop

    Designating local next hop indicates that all subnets in the VPC are reachable for the destination prefix.

  • Internet Gateway Next Hop

    This next hop is used for traffic destined to the Internet. All virtual machines using the Internet gateway next hop are required to use an Elastic IP to reach the Internet, because the subnet IPs are private IPs.

  • NAT instance

    To create this next hop, the user needs to launch a virtual machine that provides network address translation (NAT) service. The virtual machine has two interfaces: one internal and one external, both of which are automatically created. The only requirement here is that a “public” network should have been provisioned by the admin, because the second interface of the virtual machine is created in the “public” network.

Internet Gateway Next Hop Euca2ools CLI

The following euca2ools CLI commands are used to create, define, and delete Internet gateway next hop:

  • euca-attach-internet-gateway

  • euca-create-internet-gateway

  • euca-delete-internet-gateway

  • euca-describe-internet-gateways

  • euca-detach-internet-gateway

NAT Instance Next Hop Euca2ools CLI

The following euca2ools CLI commands are used to create, define, and delete NAT instance next hops:

  • euca-run-instances

  • euca-terminate-instances

Example: Creating a NAT Instance with Euca2ools CLI

The following example creates a NAT instance and creates a default route pointing to the NAT instance.