Add AwsCloudWatchMetricAlarmInvalidUnitDetector

detector/aws_cloudwatch_metric_alarm_invalid_unit.go

@@ -0,0 +1,82 @@
+package detector
+
+import (
+	"fmt"
+
+	"github.com/hashicorp/hcl/hcl/ast"
+	"github.com/wata727/tflint/issue"
+)
+
+type AwsCloudWatchMetricAlarmInvalidUnitDetector struct {
+	*Detector
+	IssueType  string
+	Target     string
+	DeepCheck  bool
+	validUnits map[string]bool
+}
+
+func (d *Detector) CreateAwsCloudWatchMetricAlarmInvalidUnitDetector() *AwsCloudWatchMetricAlarmInvalidUnitDetector {
+	return &AwsCloudWatchMetricAlarmInvalidUnitDetector{
+		Detector:   d,
+		IssueType:  issue.ERROR,
+		Target:     "aws_cloudwatch_metric_alarm",
+		DeepCheck:  false,
+		validUnits: map[string]bool{},
+	}
+}
+
+func (d *AwsCloudWatchMetricAlarmInvalidUnitDetector) PreProcess() {
+	// Ref: http://docs.aws.amazon.com/cli/latest/reference/cloudwatch/put-metric-alarm.html
+	d.validUnits = map[string]bool{
+		"Seconds":          true,
+		"Microseconds":     true,
+		"Milliseconds":     true,
+		"Bytes":            true,
+		"Kilobytes":        true,
+		"Megabytes":        true,
+		"Gigabytes":        true,
+		"Terabytes":        true,
+		"Bits":             true,
+		"Kilobits":         true,
+		"Megabits":         true,
+		"Gigabits":         true,
+		"Terabits":         true,
+		"Percent":          true,
+		"Count":            true,
+		"Bytes/Second":     true,
+		"Kilobytes/Second": true,
+		"Megabytes/Second": true,
+		"Gigabytes/Second": true,
+		"Terabytes/Second": true,
+		"Bits/Second":      true,
+		"Kilobits/Second":  true,
+		"Megabits/Second":  true,
+		"Gigabits/Second":  true,
+		"Terabits/Second":  true,
+		"Count/Second":     true,
+		"None":             true,
+	}
+}
+
+func (d *AwsCloudWatchMetricAlarmInvalidUnitDetector) Detect(file string, item *ast.ObjectItem, issues *[]*issue.Issue) {
+	unitToken, err := hclLiteralToken(item, "unit")
+	if err != nil {
+		d.Logger.Error(err)
+		return
+	}
+	unit, err := d.evalToString(unitToken.Text)
+	if err != nil {
+		d.Logger.Error(err)
+		return
+	}
+
+	if !d.validUnits[unit] {
+		issue := &issue.Issue{
+			Type:    d.IssueType,
+			Message: fmt.Sprintf("\"%s\" is invalid unit.", unit),
+			Line:    unitToken.Pos.Line,
+			File:    file,
+		}
+		*issues = append(*issues, issue)
+	}
+}

detector/aws_cloudwatch_metric_alarm_invalid_unit_test.go

@@ -0,0 +1,94 @@
+package detector
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/k0kubun/pp"
+	"github.com/wata727/tflint/config"
+	"github.com/wata727/tflint/issue"
+)
+
+func TestAwsCloudWatchMetricAlarmInvalidUnit(t *testing.T) {
+	cases := []struct {
+		Name   string
+		Src    string
+		Issues []*issue.Issue
+	}{
+		{
+			Name: "GB is invalid",
+			Src: `
+resource "aws_cloudwatch_metric_alarm" "test" {
+    metric_name         = "FreeableMemory"
+    namespace           = "AWS/RDS"
+
+    period    = "300"
+    statistic = "Average"
+    threshold = "1"
+    unit      = "GB"
+}`,
+			Issues: []*issue.Issue{
+				{
+					Type:    "ERROR",
+					Message: "\"GB\" is invalid unit.",
+					Line:    9,
+					File:    "test.tf",
+				},
+			},
+		},
+		{
+			Name: "Lowercase is invalid",
+			Src: `
+resource "aws_cloudwatch_metric_alarm" "test" {
+    metric_name         = "FreeableMemory"
+    namespace           = "AWS/RDS"
+
+    period    = "300"
+    statistic = "Average"
+    threshold = "1"
+    unit      = "gigabytes"
+}`,
+			Issues: []*issue.Issue{
+				{
+					Type:    "ERROR",
+					Message: "\"gigabytes\" is invalid unit.",
+					Line:    9,
+					File:    "test.tf",
+				},
+			},
+		},
+		{
+			Name: "Gigabytes is valid",
+			Src: `
+resource "aws_cloudwatch_metric_alarm" "test" {
+    metric_name         = "FreeableMemory"
+    namespace           = "AWS/RDS"
+
+    period    = "300"
+    statistic = "Average"
+    threshold = "1"
+    unit      = "Gigabytes"
+}`,
+			Issues: []*issue.Issue{},
+		},
+	}
+
+	for _, tc := range cases {
+		var issues = []*issue.Issue{}
+		err := TestDetectByCreatorName(
+			"CreateAwsCloudWatchMetricAlarmInvalidUnitDetector",
+			tc.Src,
+			"",
+			config.Init(),
+			config.Init().NewAwsClient(),
+			&issues,
+		)
+		if err != nil {
+			t.Fatalf("\nERROR: %s", err)
+		}
+
+		if !reflect.DeepEqual(issues, tc.Issues) {
+			t.Fatalf("\nBad: %s\nExpected: %s\n\ntestcase: %s", pp.Sprint(issues), pp.Sprint(tc.Issues), tc.Name)
+		}
+	}
+}

detector/detector.go

@@ -72,6 +72,7 @@ var detectors = map[string]string{
 	"aws_route_invalid_vpc_peering_connection":        "CreateAwsRouteInvalidVpcPeeringConnectionDetector",
 	"aws_route_invalid_instance":                      "CreateAwsRouteInvalidInstanceDetector",
 	"aws_route_invalid_network_interface":             "CreateAwsRouteInvalidNetworkInterfaceDetector",
+	"aws_cloudwatch_metric_alarm_invalid_unit":        "CreateAwsCloudWatchMetricAlarmInvalidUnitDetector",
 }
 
 func NewDetector(templates map[string]*ast.File, state *state.TFState, tfvars []*ast.File, c *config.Config) (*Detector, error) {

docs/README.md

@@ -28,6 +28,8 @@ Issues are classified into the following three types.
 - **AWS Route**
     - [aws_route_not_specified_target](aws_route_not_specified_target.md)
     - [aws_route_specified_multiple_targets](aws_route_specified_multiple_targets.md)
+- **AWS CloudWatch Metric Alarm**
+    - [aws_cloudwatch_metric_alarm_invalid_unit](aws_cloudwatch_metric_alarm_invalid_unit.md)
 - **Terraform**
     - [terraform_module_pinned_source](terraform_module_pinned_source.md)
 

docs/aws_cloudwatch_metric_alarm_invalid_unit.md

@@ -0,0 +1,62 @@
+# AWS CloudWatch Metric Alarm Invalid Unit
+This issue reported if you specify invalid unit. This issue type is ERROR.
+
+## Example
+```
+resource "aws_cloudwatch_metric_alarm" "rds-writer-memory" {
+  alarm_name                = "terraform-test-foobar5"
+  comparison_operator       = "GreaterThanOrEqualToThreshold"
+  evaluation_periods        = "2"
+  metric_name               = "CPUUtilization"
+  namespace                 = "AWS/EC2"
+  period                    = "120"
+  statistic                 = "Average"
+  threshold                 = "80"
+  unit                      = "percent" // valid unit is "Percent"
+  alarm_description         = "This metric monitor ec2 cpu utilization"
+  insufficient_data_actions = []
+}
+```
+
+The following is the execution result of TFLint:
+
+```
+template.tf
+	ERROR:10 "percent" is invalid unit.
+
+Result: 1 issues  (1 errors , 0 warnings , 0 notices)
+```
+
+## Why
+Only the followings are supported for CloudWatch alarm unit. If an invalid unit is specified, an error will occur at `terraform apply`.
+
+- Seconds
+- Microseconds
+- Milliseconds
+- Bytes
+- Kilobytes
+- Megabytes
+- Gigabytes
+- Terabytes
+- Bits
+- Kilobits
+- Megabits
+- Gigabits
+- Terabits
+- Percent
+- Count
+- Bytes/Second
+- Kilobytes/Second
+- Megabytes/Second
+- Gigabytes/Second
+- Terabytes/Second
+- Bits/Second
+- Kilobits/Second
+- Megabits/Second
+- Gigabits/Second
+- Terabits/Second
+- Count/Second
+- None
+
+## How To Fix
+Check the unit and select a valid unit again.

integration/general/.terraform/modules/0cf2d4dab02de8de33c7058799b6f81e/aws_db_instance.tf

@@ -6,7 +6,7 @@ resource "aws_db_instance" "mysql" {
   allocated_storage    = 10
   engine               = "mysql"
   engine_version       = "5.6.17"
-  instance_class       = "${var.mysql_types[0]}}"   // aws_db_instance_invalid_type
+  instance_class       = "${var.mysql_types[0]}"   // aws_db_instance_invalid_type
   name                 = "mydb"
   username             = "foo"
   password             = "secret_password"          // aws_db_instance_readable_password

integration/general/result.json

@@ -67,7 +67,7 @@
   },
   {
     "type": "ERROR",
-    "message": "\"t1.micro}\" is invalid instance type.",
+    "message": "\"t1.micro\" is invalid instance type.",
     "line": 9,
     "file": "github.com/wata727/example-module/aws_db_instance.tf"
   },
@@ -86,7 +86,13 @@
   {
     "type": "WARNING",
     "message": "Module source \"github.com/wata727/example-module\" is not pinned",
-    "line": 35,
+    "line": 49,
+    "file": "template.tf"
+  },
+  {
+    "type": "ERROR",
+    "message": "\"percent\" is invalid unit.",
+    "line": 43,
     "file": "template.tf"
   }
 ]

integration/general/template.tf

@@ -31,6 +31,20 @@ resource "aws_route" "multiple_specified" {
   egress_only_gateway_id = "eigw-1234abcd"
 }
 
+resource "aws_cloudwatch_metric_alarm" "rds-writer-memory" {
+  alarm_name                = "terraform-test-foobar5"
+  comparison_operator       = "GreaterThanOrEqualToThreshold"
+  evaluation_periods        = "2"
+  metric_name               = "CPUUtilization"
+  namespace                 = "AWS/EC2"
+  period                    = "120"
+  statistic                 = "Average"
+  threshold                 = "80"
+  unit                      = "percent" // aws_cloudwatch_metric_alarm_invalid_unit
+  alarm_description         = "This metric monitor ec2 cpu utilization"
+  insufficient_data_actions = []
+}
+
 module "ec2_instance" {
   source         = "github.com/wata727/example-module" // terraform_module_pinned_source
   instance_types = "${var.instance_type}"