Add validations for K8s resource fields (#2772)

This PR adds some validation methods for K8s resource fields.

Fixes #1405.

azurerm/helpers/validate/kubernetes.go

@@ -0,0 +1,39 @@
+package validate
+
+import (
+	"fmt"
+	"regexp"
+)
+
+func KubernetesAdminUserName(i interface{}, k string) (warnings []string, errors []error) {
+	adminUserName := i.(string)
+
+	re := regexp.MustCompile(`^[A-Za-z][-A-Za-z0-9_]*$`)
+	if re != nil && !re.MatchString(adminUserName) {
+		errors = append(errors, fmt.Errorf("%s must start with alphabet and/or continue with alphanumeric characters, underscores, hyphens. Got %q.", k, adminUserName))
+	}
+
+	return warnings, errors
+}
+
+func KubernetesAgentPoolName(i interface{}, k string) (warnings []string, errors []error) {
+	agentPoolName := i.(string)
+
+	re := regexp.MustCompile(`^[a-z]{1}[a-z0-9]{0,11}$`)
+	if re != nil && !re.MatchString(agentPoolName) {
+		errors = append(errors, fmt.Errorf("%s must start with a lowercase letter, have max length of 12, and only have characters a-z0-9. Got %q.", k, agentPoolName))
+	}
+
+	return warnings, errors
+}
+
+func KubernetesDNSPrefix(i interface{}, k string) (warnings []string, errors []error) {
+	dnsPrefix := i.(string)
+
+	re := regexp.MustCompile(`^[a-zA-Z][-a-zA-Z0-9]{0,43}[a-zA-Z0-9]$`)
+	if re != nil && !re.MatchString(dnsPrefix) {
+		errors = append(errors, fmt.Errorf("%s must contain between 2 and 45 characters. The name can contain only letters, numbers, and hyphens. The name must start with a letter and must end with an alphanumeric character.. Got %q.", k, dnsPrefix))
+	}
+
+	return warnings, errors
+}

azurerm/helpers/validate/kubernetes_test.go

@@ -0,0 +1,135 @@
+package validate
+
+import (
+	"testing"
+)
+
+func TestKubernetesAdminUserName(t *testing.T) {
+	cases := []struct {
+		AdminUserName string
+		Errors        int
+	}{
+		{
+			AdminUserName: "",
+			Errors:        1,
+		},
+		{
+			AdminUserName: "Abc-123_abc",
+			Errors:        0,
+		},
+		{
+			AdminUserName: "123abc",
+			Errors:        1,
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.AdminUserName, func(t *testing.T) {
+			_, errors := KubernetesAdminUserName(tc.AdminUserName, "test")
+
+			if len(errors) != tc.Errors {
+				t.Fatalf("Expected AdminUserName to return %d error(s) not %d", tc.Errors, len(errors))
+			}
+		})
+	}
+}
+
+func TestKubernetesAgentPoolName(t *testing.T) {
+	cases := []struct {
+		AgentPoolName string
+		Errors        int
+	}{
+		{
+			AgentPoolName: "",
+			Errors:        1,
+		},
+		{
+			AgentPoolName: "ABC123",
+			Errors:        1,
+		},
+		{
+			AgentPoolName: "abc123",
+			Errors:        0,
+		},
+		{
+			AgentPoolName: "123abc",
+			Errors:        1,
+		},
+		{
+			AgentPoolName: "hi",
+			Errors:        0,
+		},
+		{
+			AgentPoolName: "hello",
+			Errors:        0,
+		},
+		{
+			AgentPoolName: "hello-world",
+			Errors:        1,
+		},
+		{
+			AgentPoolName: "helloworld123",
+			Errors:        1,
+		},
+		{
+			AgentPoolName: "hello_world",
+			Errors:        1,
+		},
+		{
+			AgentPoolName: "Hello-World",
+			Errors:        1,
+		},
+		{
+			AgentPoolName: "20202020",
+			Errors:        1,
+		},
+		{
+			AgentPoolName: "h20202020",
+			Errors:        0,
+		},
+		{
+			AgentPoolName: "ABC123!@£",
+			Errors:        1,
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.AgentPoolName, func(t *testing.T) {
+			_, errors := KubernetesAgentPoolName(tc.AgentPoolName, "test")
+
+			if len(errors) != tc.Errors {
+				t.Fatalf("Expected AgentPoolName to return %d error(s) not %d", tc.Errors, len(errors))
+			}
+		})
+	}
+}
+
+func TestKubernetesDNSPrefix(t *testing.T) {
+	cases := []struct {
+		DNSPrefix string
+		Errors    int
+	}{
+		{
+			DNSPrefix: "",
+			Errors:    1,
+		},
+		{
+			DNSPrefix: "a",
+			Errors:    1,
+		},
+		{
+			DNSPrefix: "aBc-123abc",
+			Errors:    0,
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.DNSPrefix, func(t *testing.T) {
+			_, errors := KubernetesDNSPrefix(tc.DNSPrefix, "test")
+
+			if len(errors) != tc.Errors {
+				t.Fatalf("Expected DNSPrefix to return %d error(s) not %d", tc.Errors, len(errors))
+			}
+		})
+	}
+}

azurerm/helpers/validate/network.go

@@ -3,6 +3,7 @@ package validate
 import (
 	"fmt"
 	"net"
+	"regexp"
 )
 
 func IPv6Address(i interface{}, k string) (warnings []string, errors []error) {
@@ -29,6 +30,17 @@ func validateIpv6Address(i interface{}, k string, allowEmpty bool) (warnings []s
 
 }
 
+func CIDR(i interface{}, k string) (warnings []string, errors []error) {
+	cidr := i.(string)
+
+	re := regexp.MustCompile(`^([0-9]{1,3}\.){3}[0-9]{1,3}(\/([0-9]|[1-2][0-9]|3[0-2]))?$`)
+	if re != nil && !re.MatchString(cidr) {
+		errors = append(errors, fmt.Errorf("%s must start with IPV4 address and/or slash, number of bits (0-32) as prefix. Example: 127.0.0.1/8. Got %q.", k, cidr))
+	}
+
+	return warnings, errors
+}
+
 func IPv4Address(i interface{}, k string) (warnings []string, errors []error) {
 	return validateIpv4Address(i, k, false)
 }

azurerm/helpers/validate/network_test.go

@@ -5,6 +5,44 @@ import (
 	"testing"
 )
 
+func TestCIDR(t *testing.T) {
+	cases := []struct {
+		CIDR   string
+		Errors int
+	}{
+		{
+			CIDR:   "",
+			Errors: 1,
+		},
+		{
+			CIDR:   "0.0.0.0",
+			Errors: 0,
+		},
+		{
+			CIDR:   "127.0.0.1/8",
+			Errors: 0,
+		},
+		{
+			CIDR:   "127.0.0.1/33",
+			Errors: 1,
+		},
+		{
+			CIDR:   "127.0.0.1/-1",
+			Errors: 1,
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.CIDR, func(t *testing.T) {
+			_, errors := CIDR(tc.CIDR, "test")
+
+			if len(errors) != tc.Errors {
+				t.Fatalf("Expected CIDR to return %d error(s) not %d", tc.Errors, len(errors))
+			}
+		})
+	}
+}
+
 func TestIPv6Address(t *testing.T) {
 	cases := []struct {
 		IP     string