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subnet.go
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subnet.go
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package vpc
import (
"context"
"errors"
"fmt"
"strings"
"github.com/aws/aws-sdk-go-v2/aws"
"github.com/aws/aws-sdk-go-v2/service/ec2"
ec2types "github.com/aws/aws-sdk-go-v2/service/ec2/types"
log "github.com/cantara/bragi/sbragi"
"github.com/cantara/nerthus2/cloud/aws/az"
)
type Subnet struct {
VPC string
AZ string
Id string
Name string
CIDR string
CIDRv6 string
}
func SubnetsToIds(subnets []Subnet) (out []string) {
out = make([]string, len(subnets))
for i, s := range subnets {
out[i] = s.Id
}
return
}
func GetSubnets(v string, e2 *ec2.Client) (subnets []Subnet, err error) {
v = strings.ToLower(v)
log.Trace("getting subnets", "vpc", v)
result, err := e2.DescribeSubnets(context.Background(), &ec2.DescribeSubnetsInput{
Filters: []ec2types.Filter{
{
Name: aws.String("vpc-id"),
Values: []string{
v,
},
},
},
})
if err != nil {
err = fmt.Errorf("Unable to describe Subnets, err: %v", err)
return
}
if len(result.Subnets) == 0 {
log.Trace("no subnets found")
err = ErrNoSubnetsFound
return
}
for _, s := range result.Subnets {
name := Tag(s.Tags, "name")
subnets = append(subnets, Subnet{
VPC: v,
AZ: *s.AvailabilityZoneId,
Id: *s.SubnetId,
Name: name,
CIDR: *s.CidrBlock,
CIDRv6: *s.Ipv6CidrBlockAssociationSet[0].Ipv6CidrBlock, //TODO: this can error
})
}
return
}
func CreateSubnets(vpc VPC, e2 *ec2.Client) (err error) {
azs, err := az.GetAZs(e2)
if err != nil {
return
}
subnets, err := GetSubnets(vpc.Id, e2)
if err != nil && !errors.Is(err, ErrNoSubnetsFound) {
return err
}
if len(azs) == len(subnets) {
log.Info("number of subnets equal availability zones")
return nil
}
cidrBase := strings.Join(strings.Split(vpc.CIDR, ".")[:3], ".")
cidrV6Base := vpc.CIDRv6[:len(vpc.CIDRv6)-6]
name := strings.TrimSuffix(vpc.Name, "-vpc")
for i, az := range azs {
if subnetInAz(az, subnets) {
continue
}
cidr := fmt.Sprintf("%s.%d/26", cidrBase, 64*(i%4))
cidrV6 := fmt.Sprintf("%s%d::/64", cidrV6Base, i)
result, err := e2.CreateSubnet(context.Background(), &ec2.CreateSubnetInput{
VpcId: &vpc.Id,
AvailabilityZoneId: &az,
CidrBlock: &cidr,
Ipv6CidrBlock: &cidrV6,
TagSpecifications: []ec2types.TagSpecification{
{
ResourceType: ec2types.ResourceTypeSubnet,
Tags: []ec2types.Tag{
{
Key: aws.String("Name"),
Value: aws.String(fmt.Sprintf("%s-subnet-%d", name, i+1)),
},
},
},
},
})
if err != nil {
return err
}
log.Trace("created subnet", "result", result)
}
return
}
func subnetInAz(az string, subnets []Subnet) bool {
for _, s := range subnets {
if s.AZ == az {
return true
}
}
return false
}
var ErrNoSubnetsFound = fmt.Errorf("no subnets found")