updated node/docs/cert.md

Author: DergachevE

node/docs/cert.md

@@ -0,0 +1,92 @@
+### Get certificate configuration by using [AZURE-PIPELINES-TASK-LIB](https://github.com/Microsoft/azure-pipelines-task-lib) method (Min Agent Version 2.122.0)
+
+#### Node.js Lib
+
+Method for retrieve certificate settings in node.js lib
+``` typescript
+export function getHttpCertConfiguration(): CertConfiguration {
+}
+```
+`CertConfiguration` has following fields
+```typescript
+export interface CertConfiguration {
+     caFile?: string;
+     certFile?: string;
+     keyFile?: string;
+     certArchiveFile?: string;
+     passphrase?: string;
+ }
+```
+
+In the following example, we will retrieve certificate configuration information and use VSTS-Node-Api to make a Rest Api call back to VSTS/TFS service, the Rest call will use the certificates you configured in agent.
+```typescript
+// MyCertExampleTask.ts
+import tl = require('azure-pipelines-task-lib/task');
+import api = require('vso-node-api');
+import VsoBaseInterfaces = require('vso-node-api/interfaces/common/VsoBaseInterfaces');
+
+async function run() {
+
+    // get cert config
+    let cert = tl.getHttpCertConfiguration();
+
+    // TFS server url
+    let serverUrl = "https://mycompanytfs.com/tfs";
+
+    // Personal access token
+    let token = "<YOUR_TOKEN_HERE>";
+    let authHandler = api.getPersonalAccessTokenHandler(token);
+
+    // Options for VSTS-Node-Api, 
+    // this is not required if you want to send http request to the same TFS
+    // instance the agent currently connect to.
+    // VSTS-Node-Api will pick up certificate setting from azure-pipelines-task-lib automatically 
+    let option: VsoBaseInterfaces.IRequestOptions = {
+        cert: {
+                caFile: "C:\\ca.pem",
+                certFile: "C:\\client-cert.pem",
+                keyFile: "C:\\client-cert-key.pem",
+                passphrase: "test123",
+            }
+        };
+    
+    // Make a Rest call to VSTS/TFS
+    let vsts: api.WebApi = new api.WebApi(serverUrl, authHandler, option);
+    let connData: lim.ConnectionData = await vsts.connect();
+    console.log('Hello ' + connData.authenticatedUser.providerDisplayName);
+
+    // You should only use the retrieved certificate config to call the TFS instance your agent current connect to or any resource within your cooperation that accept those certificates.
+}
+
+run();
+```
+
+#### PowerShell Lib
+
+On Windows the CA certificate needs to be installed into the `Trusted CA Store` of `Windows Certificate manager` first.
+So the PowerShell lib will only expose the client certificate information
+
+Method for retrieve client certificate settings in PowerShell lib
+``` powershell
+function Get-ClientCertificate {
+    [CmdletBinding()]
+    param()
+
+    # Return a new X509Certificate2 object to the client certificate
+    return New-Object -TypeName System.Security.Cryptography.X509Certificates.X509Certificate2
+}
+```
+
+In the following example, we will retrieve client certificate configuration information and print it out first, then we will use PowerShell lib method to get `VssHttpClient` and make a Rest Api call back to TFS service's `Project` endpoint and retrieve all team projects. The Rest call will use the client certificate you configured in agent.
+
+```powershell
+# retrieve cert config
+$cert = Get-VstsClientCertificate
+Write-Host $cert
+
+# get project http client (the client will have proxy hook up by default)
+$projectHttpClient = Get-VstsVssHttpClient -TypeName Microsoft.TeamFoundation.Core.WebApi.ProjectHttpClient -OMDirectory "<Directory that contains required .dlls>"
+
+# print out all team projects
+$projectHttpClient.GetProjects().Result
+```