Add API client for Azure custom vnet (#271)

* Update vendor for azure vent support

* Add support for Azure custom vnets.

Use pointers intead of values. This allows the client to pass back
returned data from Azure.

providers/azure/client/network/subnet.go

@@ -0,0 +1,154 @@
+package network
+
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+	"net/url"
+
+	"github.com/Azure/azure-sdk-for-go/services/network/mgmt/2018-05-01/network"
+	"github.com/pkg/errors"
+	"github.com/virtual-kubelet/virtual-kubelet/providers/azure/client/api"
+)
+
+const (
+	subnetPath = "subscriptions/{{.subscriptionId}}/resourcegroups/{{.resourceGroupName}}/providers/Microsoft.Network/virtualNetworks/{{.vnetName}}/subnets/{{.subnetName}}"
+)
+
+// Subnet represents an Azure subnet
+type Subnet struct {
+	Name       string
+	ID         string
+	Properties *SubnetProperties
+}
+
+// SubnetProperties are the properties for a subne
+type SubnetProperties struct {
+	AddressPrefix string `json:"addressPrefix,omitempty"`
+
+	// IPConfigurationProfiles and Delegations are new fields not available in the SDK yet
+	IPConfigurationProfiles []SubnetIPConfigurationProfile `json:"ipConfigurationProfiles"`
+	Delegations             []Delegation
+
+	// copied from official go SDK, none of these are used here except to make sure we don't nil out some data on fetched objects.
+	// NetworkSecurityGroup - The reference of the NetworkSecurityGroup resource.
+	NetworkSecurityGroup *network.SecurityGroup `json:"networkSecurityGroup,omitempty"`
+	// RouteTable - The reference of the RouteTable resource.
+	RouteTable *network.RouteTable `json:"routeTable,omitempty"`
+	// ServiceEndpoints - An array of service endpoints.
+	ServiceEndpoints *[]network.ServiceEndpointPropertiesFormat `json:"serviceEndpoints,omitempty"`
+	// IPConfigurations - Gets an array of references to the network interface IP configurations using subnet.
+	IPConfigurations *[]network.IPConfiguration `json:"ipConfigurations,omitempty"`
+	// ResourceNavigationLinks - Gets an array of references to the external resources using subnet.
+	ResourceNavigationLinks *[]network.ResourceNavigationLink `json:"resourceNavigationLinks,omitempty"`
+	// ProvisioningState - The provisioning state of the resource.
+	ProvisioningState *string `json:"provisioningState,omitempty"`
+}
+
+// SubnetIPConfigurationProfile stores the ID for an assigned network profile
+type SubnetIPConfigurationProfile struct {
+	ID string
+}
+
+// Delegation stores the subnet delegation details
+type Delegation struct {
+	Name       string
+	ID         string
+	ETag       string
+	Properties DelegationProperties
+}
+
+// DelegationProperties stores the properties for a delegation
+type DelegationProperties struct {
+	ServiceName string
+	Actions     []string
+}
+
+// GetSubnet gets the subnet from the specified resourcegroup/vnet
+func (c *Client) GetSubnet(resourceGroup, vnet, name string) (*Subnet, error) {
+	urlParams := url.Values{
+		"api-version": []string{apiVersion},
+	}
+
+	// Create the url.
+	uri := api.ResolveRelative(baseURI, subnetPath)
+	uri += "?" + url.Values(urlParams).Encode()
+
+	req, err := http.NewRequest("GET", uri, nil)
+	if err != nil {
+		return nil, errors.Wrap(err, "creating subnet get uri request failed")
+	}
+
+	if err := api.ExpandURL(req.URL, map[string]string{
+		"subscriptionId":    c.auth.SubscriptionID,
+		"resourceGroupName": resourceGroup,
+		"subnetName":        name,
+		"vnetName":          vnet,
+	}); err != nil {
+		return nil, errors.Wrap(err, "expanding URL with parameters failed")
+	}
+
+	// Send the request.
+	resp, err := c.hc.Do(req)
+	if err != nil {
+		return nil, errors.Wrap(err, "sending subnet get request failed")
+	}
+	defer resp.Body.Close()
+
+	// 200 (OK) is a success response.
+	if err := api.CheckResponse(resp); err != nil {
+		return nil, err
+	}
+
+	var subnet Subnet
+	if err := json.NewDecoder(resp.Body).Decode(&subnet); err != nil {
+		return nil, err
+	}
+	return &subnet, nil
+}
+
+// CreateOrUpdateSubnet creates a new or updates an existing subnet in the defined resourcegroup/vnet
+func (c *Client) CreateOrUpdateSubnet(resourceGroup, vnet string, subnet *Subnet) error {
+	urlParams := url.Values{
+		"api-version": []string{apiVersion},
+	}
+
+	// Create the url.
+	uri := api.ResolveRelative(baseURI, subnetPath)
+	uri += "?" + url.Values(urlParams).Encode()
+
+	// Create the request.
+	b, err := json.Marshal(subnet)
+	if err != nil {
+		return errors.Wrap(err, "marshallig networking profile failed")
+	}
+
+	req, err := http.NewRequest("PUT", uri, bytes.NewReader(b))
+	if err != nil {
+		return errors.New("creating subnet create uri request failed")
+	}
+
+	// Add the parameters to the url.
+	if err := api.ExpandURL(req.URL, map[string]string{
+		"subscriptionId":    c.auth.SubscriptionID,
+		"resourceGroupName": resourceGroup,
+		"subnetName":        subnet.Name,
+		"vnetName":          vnet,
+	}); err != nil {
+		return errors.Wrap(err, "expanding URL with parameters failed")
+	}
+
+	// Send the request.
+	resp, err := c.hc.Do(req)
+	if err != nil {
+		return errors.Wrap(err, "sending create subnet request failed")
+	}
+	defer resp.Body.Close()
+
+	// 200 (OK) is a success response.
+	if err := api.CheckResponse(resp); err != nil {
+		return err
+	}
+
+	return errors.Wrap(json.NewDecoder(resp.Body).Decode(subnet), "error decoding create subnet response")
+}