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Add a workaround for CloudFormation update issues #162

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merged 1 commit into from
May 15, 2018
Merged

Add a workaround for CloudFormation update issues #162

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82 changes: 50 additions & 32 deletions aws/cf_template.go
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Original file line number Diff line number Diff line change
Expand Up @@ -6,8 +6,21 @@ import (
"time"

"github.com/mweagle/go-cloudformation"
"sort"
"crypto/sha256"
)

func hashARNs(certARNs []string) []byte {
hash := sha256.New()

for _, arn := range certARNs {
hash.Write([]byte(arn))
hash.Write([]byte{'\000'})
}

return hash.Sum(nil)
}

func generateTemplate(certs map[string]time.Time, idleConnectionTimeoutSeconds uint) (string, error) {
template := cloudformation.NewTemplate()
template.Description = "Load Balancer for Kubernetes Ingress"
Expand Down Expand Up @@ -58,46 +71,51 @@ func generateTemplate(certs map[string]time.Time, idleConnectionTimeoutSeconds u
})

if len(certs) > 0 {
certificateARNs := make(cloudformation.ElasticLoadBalancingV2ListenerCertificateCertificateList, 0, len(certs)-1)
first := true
for certARN, _ := range certs {
if first {
defaultCertificateARN := cloudformation.ElasticLoadBalancingV2ListenerCertificatePropertyList{
{
CertificateArn: cloudformation.String(certARN),
},
}

template.AddResource("HTTPSListener", &cloudformation.ElasticLoadBalancingV2Listener{
DefaultActions: &cloudformation.ElasticLoadBalancingV2ListenerActionList{
{
Type: cloudformation.String("forward"),
TargetGroupArn: cloudformation.Ref("TG").String(),
},
},
Certificates: &defaultCertificateARN,
LoadBalancerArn: cloudformation.Ref("LB").String(),
Port: cloudformation.Integer(443),
Protocol: cloudformation.String("HTTPS"),
})
// Sort the certificate names so we have a stable order. As a nice side effect, a wildcard cert will always
// be selected as the default one if it's present.
certificateARNs := make([]string, 0, len(certs))
for certARN := range certs {
certificateARNs = append(certificateARNs, certARN)
}
sort.Slice(certificateARNs, func(i, j int) bool {
return certificateARNs[i] < certificateARNs[j]
})

first = false
continue
}
// Add an HTTPS Listener resource with the first certificate as the default one
template.AddResource("HTTPSListener", &cloudformation.ElasticLoadBalancingV2Listener{
DefaultActions: &cloudformation.ElasticLoadBalancingV2ListenerActionList{
{
Type: cloudformation.String("forward"),
TargetGroupArn: cloudformation.Ref("TG").String(),
},
},
Certificates: &cloudformation.ElasticLoadBalancingV2ListenerCertificatePropertyList{
{
CertificateArn: cloudformation.String(certificateARNs[0]),
},
},
LoadBalancerArn: cloudformation.Ref("LB").String(),
Port: cloudformation.Integer(443),
Protocol: cloudformation.String("HTTPS"),
})

// Add a ListenerCertificate resource with all of the certificates, including the default one
certificateList := make(cloudformation.ElasticLoadBalancingV2ListenerCertificateCertificateList, 0, len(certificateARNs))
for _, certARN := range certificateARNs {
c := cloudformation.ElasticLoadBalancingV2ListenerCertificateCertificate{
CertificateArn: cloudformation.String(certARN),
}
certificateARNs = append(certificateARNs, c)
certificateList = append(certificateList, c)
}

if len(certificateARNs) > 0 {
template.AddResource("HTTPSListenerCertificate", &cloudformation.ElasticLoadBalancingV2ListenerCertificate{
Certificates: &certificateARNs,
ListenerArn: cloudformation.Ref("HTTPSListener").String(),
})
}
// Use a new resource name every time to avoid a bug where CloudFormation fails to perform an update properly
resourceName := fmt.Sprintf("HTTPSListenerCertificate_%x", hashARNs(certificateARNs))
template.AddResource(resourceName, &cloudformation.ElasticLoadBalancingV2ListenerCertificate{
Certificates: &certificateList,
ListenerArn: cloudformation.Ref("HTTPSListener").String(),
})
}

template.AddResource("LB", &cloudformation.ElasticLoadBalancingV2LoadBalancer{
LoadBalancerAttributes: &cloudformation.ElasticLoadBalancingV2LoadBalancerLoadBalancerAttributeList{
cloudformation.ElasticLoadBalancingV2LoadBalancerLoadBalancerAttribute{
Expand Down