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provider/aws: Expose ARN suffix on ALB
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When creating a CloudWatch Metric for an Application Load Balancer it is
neccessary to use the suffix of the ARN as the reference to the load
balancer. This commit exposes that as an attribute on the `aws_alb`
resource to prevent the need to use regular expression substitution to
make the reference.

Fixes #8808.
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jen20 committed Sep 14, 2016
1 parent a0a59d3 commit 339919d
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Showing 3 changed files with 57 additions and 4 deletions.
21 changes: 21 additions & 0 deletions builtin/providers/aws/resource_aws_alb.go
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ package aws
import (
"fmt"
"log"
"regexp"
"strconv"

"github.com/aws/aws-sdk-go/aws"
Expand All @@ -28,6 +29,11 @@ func resourceAwsAlb() *schema.Resource {
Computed: true,
},

"arn_suffix": {
Type: schema.TypeString,
Computed: true,
},

"name": {
Type: schema.TypeString,
Optional: true,
Expand Down Expand Up @@ -191,6 +197,7 @@ func resourceAwsAlbRead(d *schema.ResourceData, meta interface{}) error {
alb := describeResp.LoadBalancers[0]

d.Set("arn", alb.LoadBalancerArn)
d.Set("arn_suffix", albSuffixFromARN(alb.LoadBalancerArn))
d.Set("name", alb.LoadBalancerName)
d.Set("internal", (alb.Scheme != nil && *alb.Scheme == "internal"))
d.Set("security_groups", flattenStringList(alb.SecurityGroups))
Expand Down Expand Up @@ -345,3 +352,17 @@ func flattenSubnetsFromAvailabilityZones(availabilityZones []*elbv2.Availability
}
return result
}

func albSuffixFromARN(arn *string) string {
if arn == nil {
return ""
}

if arnComponents := regexp.MustCompile(`arn:.*:loadbalancer/(.*)`).FindAllStringSubmatch(*arn, -1); len(arnComponents) == 1 {
if len(arnComponents[0]) == 2 {
return arnComponents[0][1]
}
}

return ""
}
31 changes: 31 additions & 0 deletions builtin/providers/aws/resource_aws_alb_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,37 @@ import (
"github.com/hashicorp/terraform/terraform"
)

func TestALBCloudwatchSuffixFromARN(t *testing.T) {
cases := []struct {
name string
arn *string
suffix string
}{
{
name: "valid suffix",
arn: aws.String(`arn:aws:elasticloadbalancing:us-east-1:123456:loadbalancer/app/my-alb/abc123`),
suffix: `app/my-alb/abc123`,
},
{
name: "no suffix",
arn: aws.String(`arn:aws:elasticloadbalancing:us-east-1:123456:loadbalancer`),
suffix: ``,
},
{
name: "nil ARN",
arn: nil,
suffix: ``,
},
}

for _, tc := range cases {
actual := albSuffixFromARN(tc.arn)
if actual != tc.suffix {
t.Fatalf("bad suffix: %q\nExpected: %s\n Got: %s", tc.name, tc.suffix, actual)
}
}
}

func TestAccAWSALB_basic(t *testing.T) {
var conf elbv2.LoadBalancer
albName := fmt.Sprintf("testaccawsalb-basic-%s", acctest.RandStringFromCharSet(10, acctest.CharSetAlphaNum))
Expand Down
9 changes: 5 additions & 4 deletions website/source/docs/providers/aws/r/alb.html.markdown
Original file line number Diff line number Diff line change
Expand Up @@ -59,11 +59,12 @@ Access Logs (`access_logs`) support the following:

The following attributes are exported in addition to the arguments listed above:

* `id` - The ARN of the load balancer (matches `arn`)
* `arn` - The ARN of the load balancer (matches `id`)
* `dns_name` - The DNS name of the load balancer
* `id` - The ARN of the load balancer (matches `arn`).
* `arn` - The ARN of the load balancer (matches `id`).
* `arn_suffix` - The ARN suffix for use with CloudWatch Metrics.
* `dns_name` - The DNS name of the load balancer.
* `canonical_hosted_zone_id` - The canonical hosted zone ID of the load balancer.
* `zone_id` - The canonical hosted zone ID of the load balancer (to be used in a Route 53 Alias record)
* `zone_id` - The canonical hosted zone ID of the load balancer (to be used in a Route 53 Alias record).

## Import

Expand Down

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