feat: look up CIDR block address range by VPC ID

README.md

@@ -344,8 +344,7 @@ ensure the security group exists.
 
 ## `getVPCIdBySubnetId(options)`
 
-Ensures that a security group with the specified name exists in the VPC, creating
-it if needed.
+Fetches and returns the ID of the VPC where the specified subnet is located.
 
 ### `options` object
 
@@ -370,3 +369,31 @@ AWS region. Either `ec2` or `region` must be provided.
 ### Returns
 
 A `Promise` that resolves to a `string` with the ID of the VPC
+
+## `getCIDRByVPCId(options)`
+
+Fetches and returns the CIDR block IP address range of the specified VPC.
+
+### `options` object
+
+#### `awsConfig` (`ConfigurationOptions`, _optional_)
+
+General AWS service configuration options like `region` and `credentials`
+
+#### `vpcId` (`string`, **required**)
+
+ID of the VPC
+
+#### `ec2` (`AWS.EC2`, **conditional**)
+
+Optional EC2 class instance to use for API calls. If no EC2 class instance
+is provided, one will be created using the `region` property. Either
+`ec2` or `region` must be provided.
+
+#### `region` (`string`, **conditional**)
+
+AWS region. Either `ec2` or `region` must be provided.
+
+### Returns
+
+A `Promise` that resolves to a `string` with the IP address range of the VPC

index.d.ts

@@ -8,4 +8,4 @@ export { default as getStackResources } from './getStackResources'
 export { default as printStackResources } from './printStackResources'
 export { getSubnetInfo } from './subnet'
 export { getSecurityGroupId, upsertSecurityGroup } from './securityGroups'
-export { getVPCIdBySubnetId } from './vpc'
+export { getVPCIdBySubnetId, getCIDRByVPCId } from './vpc'

src/index.js

@@ -12,4 +12,4 @@ export { default as printStackResources } from './printStackResources'
 export { upsertSecurityGroup, getSecurityGroupId } from './securityGroups'
 export { getSubnetInfo } from './subnet'
 export type { SubnetInfo } from './subnet'
-export { getVPCIdBySubnetId } from './vpc'
+export { getVPCIdBySubnetId, getCIDRByVPCId } from './vpc'

src/vpc.js

@@ -16,3 +16,36 @@ export async function getVPCIdBySubnetId({
 }): Promise<string> {
   return (await getSubnetInfo({ subnetId, ec2, awsConfig, region })).VpcId
 }
+
+export async function getCIDRByVPCId({
+  vpcId,
+  ec2,
+  region,
+  awsConfig,
+}: {
+  vpcId: string,
+  ec2?: ?AWS.EC2,
+  region?: ?string,
+  awsConfig?: ?{ ... },
+}): Promise<string> {
+  if (!vpcId) throw Error('vpcId is required')
+  if (!awsConfig) awsConfig = { ...(region ? { region } : {}) }
+  if (!ec2) ec2 = new AWS.EC2(awsConfig)
+  const { Vpcs } = await ec2
+    .describeVpcs({
+      VpcIds: [vpcId],
+    })
+    .promise()
+  if (!Vpcs) throw Error('missing Vpcs in result')
+  const [vpc] = Vpcs
+  if (!vpc)
+    throw Error(
+      `could not look up CIDR for VPC ${vpcId}: missing VPC in result`
+    )
+  const { CidrBlock } = vpc
+  if (!CidrBlock)
+    throw Error(
+      `could not look up CIDR for VPC ${vpcId}: missing CidrBlock on VPC object`
+    )
+  return CidrBlock
+}

vpc.d.ts

@@ -6,3 +6,10 @@ export function getVPCIdBySubnetId(options: {
   region?: string | null | undefined
   awsConfig?: AWS.ConfigurationOptions | null
 }): Promise<AWS.EC2.VpcId>
+
+export function getCIDRByVPCId(options: {
+  vpcId: AWS.EC2.VpcId
+  ec2?: AWS.EC2 | null | undefined
+  region?: string | null | undefined
+  awsConfig?: AWS.ConfigurationOptions | null
+}): Promise<string>