Added clean exec functionality + ACI implementation - V2 (#244)

* Stubs and vkubelet changes

* added dependencies

* Azure provider exec implementation

* added missing dependencies

* added vkubelet imports

* added huawei exec stub

* Fixed exec tab functionality / stdin buffer length

* Removed unused import

* Added provider function GetPodFullName + ACI implementation

* Added error handling in ACI provider exec

providers/azure/client/aci/exec.go

@@ -0,0 +1,84 @@
+package aci
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"net/url"
+
+	"github.com/virtual-kubelet/virtual-kubelet/providers/azure/client/api"
+	"k8s.io/client-go/tools/remotecommand"
+)
+
+type TerminalSizeRequest struct {
+	Width  int
+	Height int
+}
+
+// Starts the exec command for a specified container instance in a specified resource group and container group.
+// From: https://docs.microsoft.com/en-us/rest/api/container-instances/startcontainer/launchexec
+func (c *Client) LaunchExec(resourceGroup, containerGroupName, containerName, command string, terminalSize remotecommand.TerminalSize) (ExecResponse, error) {
+	urlParams := url.Values{
+		"api-version": []string{apiVersion},
+	}
+
+	// Create the url to call Azure REST API
+	uri := api.ResolveRelative(baseURI, containerExecURLPath)
+	uri += "?" + url.Values(urlParams).Encode()
+
+	var xc ExecRequest
+
+	xc.Command = command
+	xc.TerminalSize.Rows = int(terminalSize.Height)
+	xc.TerminalSize.Cols = int(terminalSize.Width)
+
+	var xcrsp ExecResponse
+	xcrsp.Password = ""
+	xcrsp.WebSocketUri = ""
+
+	b := new(bytes.Buffer)
+
+	if err := json.NewEncoder(b).Encode(xc); err != nil {
+		return xcrsp, fmt.Errorf("Encoding create launch exec body request failed: %v", err)
+	}
+
+	req, err := http.NewRequest("POST", uri, b)
+	if err != nil {
+		return xcrsp, fmt.Errorf("Creating launch exec uri request failed: %v", err)
+	}
+
+	// Add the parameters to the url.
+	if err := api.ExpandURL(req.URL, map[string]string{
+		"subscriptionId":     c.auth.SubscriptionID,
+		"resourceGroup":      resourceGroup,
+		"containerGroupName": containerGroupName,
+		"containerName":      containerName,
+	}); err != nil {
+		return xcrsp, fmt.Errorf("Expanding URL with parameters failed: %v", err)
+	}
+
+	// Send the request.
+	resp, err := c.hc.Do(req)
+	if err != nil {
+		return xcrsp, fmt.Errorf("Sending launch exec request failed: %v", err)
+	}
+	defer resp.Body.Close()
+
+	// 200 (OK) is a success response.
+	if err := api.CheckResponse(resp); err != nil {
+		return xcrsp, err
+	}
+
+	// Decode the body from the response.
+	if resp.Body == nil {
+		return xcrsp, errors.New("Create launch exec returned an empty body in the response")
+	}
+
+	if err := json.NewDecoder(resp.Body).Decode(&xcrsp); err != nil {
+		return xcrsp, fmt.Errorf("Decoding create launch exec response body failed: %v", err)
+	}
+
+	return xcrsp, nil
+}