RouteTable

Source: src/AWS/EC2/RouteTable.ts

A VPC route table holds a set of routes that determine where network traffic from associated subnets (or gateways) is directed. Create one route table per routing domain — typically a “public” table whose default route points at an InternetGateway, and one or more “private” tables whose default route points at a NAT gateway.

A route table is little more than a container: it owns a vpcId and tags, while the actual routing behaviour is supplied by separate Route resources and applied to subnets by RouteTableAssociation resources.

Creating a Route Table

The only required input is the vpcId the table belongs to. Changing vpcId later replaces the route table, since a table cannot move between VPCs.

Basic Route Table

const routeTable = yield* AWS.EC2.RouteTable("PublicRouteTable", {
  vpcId: myVpc.vpcId,
});

Creates an empty route table in the given VPC. It starts with only the implicit local route (managed by AWS) until you add your own Route resources.

Route Table with Tags

const routeTable = yield* AWS.EC2.RouteTable("PrivateRouteTable", {
  vpcId: myVpc.vpcId,
  tags: { Name: "private-rt", Tier: "private" },
});

The tags map is merged with the alchemy auto-tags (alchemy::stack, alchemy::stage, alchemy::id) and can be updated in place without replacing the table. Use the Name tag to label the table in the AWS console.

Building a Public Routing Domain

A route table only directs traffic once you attach routes to it and associate it with subnets. The pattern below wires a public subnet to the internet: an InternetGateway, a default Route pointing at it, and a RouteTableAssociation binding the subnet to the table.

const internetGateway = yield* AWS.EC2.InternetGateway("InternetGateway", {
  vpcId: myVpc.vpcId,
});

const publicRouteTable = yield* AWS.EC2.RouteTable("PublicRouteTable", {
  vpcId: myVpc.vpcId,
});

const internetRoute = yield* AWS.EC2.Route("InternetRoute", {
  routeTableId: publicRouteTable.routeTableId,
  destinationCidrBlock: "0.0.0.0/0",
  gatewayId: internetGateway.internetGatewayId,
});

const association = yield* AWS.EC2.RouteTableAssociation("PublicSubnetAssociation", {
  routeTableId: publicRouteTable.routeTableId,
  subnetId: publicSubnet.subnetId,
});

Any subnet associated with this table now reaches the public internet via the 0.0.0.0/0 route. Multiple subnets can share the same route table by declaring additional associations — a common way to give every public subnet in a VPC identical routing.