E-MapReduce:Create an SSH tunnel to access web UIs of open source components

Background information

The ports over which you can access the web UIs of open source components are disabled for security purposes. The open source components include Hadoop, Spark, and Flink in an E-MapReduce (EMR) cluster. You can access these web UIs from the EMR console. You can also create an SSH tunnel on your on-premises server and enable port forwarding to access these web UIs. Dynamic port forwarding and local port forwarding are supported.

For more information about how to access the web UIs of open source components from the EMR console, see Access the web UIs of open source components.

Prerequisites

• An EMR cluster is created. For more information, see Create a cluster.
• Your on-premises server is connected to the master node of the cluster. You can turn on Assign Public IP Address during cluster creation to associate an elastic IP address (EIP) with your cluster. You can also assign a fixed public IP address or an EIP address to the master node of your cluster in the ECS console after the cluster is created. For more information, see Bind an ENI.

Obtain the public IP address of the master node

1. Go to the Cluster Overview page.
   1. Log on to the Alibaba Cloud EMR console.
   2. In the top navigation bar, select the region where your cluster resides and select a resource group based on your business requirements.
   3. Click the Cluster Management tab.
   4. On the Cluster Management page, find your cluster and click Details in the Actions column.
2. In the Instance Info section of the Cluster Overview page, view the public IP address of the master node.
   

Obtain the name of the master node

1. Go to the Cluster Overview page.
   1. Log on to the Alibaba Cloud EMR console.
   2. In the top navigation bar, select the region where your cluster resides and select a resource group based on your business requirements.
   3. Click the Cluster Management tab.
   4. On the Cluster Management page, find your cluster and click Details in the Actions column.
2. In the left-side navigation pane of the Cluster Overview page, click Instances.
3. On the Instances page, view the node name that corresponds to the public IP address of the master node.
   For information about how to obtain the public IP address of the master node, see Obtain the public IP address of the master node.

Enable dynamic port forwarding

Create an SSH tunnel to allow communication between a port of your on-premises server and the master node of an EMR cluster. Run the on-premises SOCKS proxy server that listens on the port. The port data is forwarded to the master node of the EMR cluster by using the SSH tunnel.

1. Create an SSH tunnel.
   Important Keep your on-premises server running after the tunnel is created. No responses are returned.

   • Use a key:

     ssh -i <Storage path of the key file> -N -D 8157 root@<Public IP address of the master node>

   • Use a username and a password:

     ssh -N -D 8157 root@<Public IP address of the master node>

   Parameter description:

   • 8157: Port 8157 is used in this example. You can replace this port with an unoccupied port on your on-premises server in actual configuration.
   • -D: Dynamic port forwarding is enabled. Start the SOCKS proxy process to listen on the port.
   • <Public IP address of the master node>: For more information about how to obtain the public IP address of the master node, see Obtain the public IP address of the master node.
   • <Storage path of the key file>: the path where the key file is stored.
2. Configure the Google Chrome browser.

   You can use one of the following methods to configure the Google Chrome browser:

   • Use the CLI
     1. Open the CLI and go to the local installation directory of the Google Chrome browser client.

        The default installation directory of Google Chrome depends on the operating system.

        Operating system	Google Chrome installation directory
        Mac OS X	/Applications/Google Chrome.app/Contents/macOS/Google Chrome
        Linux	/usr/bin/google-chrome
        Windows	C:\Program Files (x86)\Google\Chrome\Application\

     2. Run the following command in the default installation directory of Google Chrome:

        chrome --proxy-server="socks5://localhost:8157" --host-resolver-rules="MAP * 0.0.0.0 , EXCLUDE localhost" --user-data-dir=/tmp/

        Parameter description:

        • /tmp/: For Windows, replace /tmp/ with a path similar to /c:/tmppath/. For Linux and macOS, the format of a file directory is /tmp/.
        • 8157: Port 8157 is used in this example. You can replace this port with an unoccupied port on your on-premises server in actual configuration.
     3. Enter http://<Name of the master node>:<Port number> in the address bar of the browser and press Enter to access a specific web UI.

        For more information about the ports of components, see Common ports of services. For more information about how to obtain the name of the master node, see Obtain the name of the master node.

        For example, enter http://emr-header-1:8088 in the address bar of the browser and press Enter to access the web UI of YARN.

   • Use a Google Chrome extension

     Extensions allow you to easily manage and use proxies in your web browser. You can use an extension to browse web pages and access web UIs at the same time.

     1. Add the Google Chrome extension Proxy SwitchyOmega.
     2. Click this extension and select Options from the shortcut menu.
     3. On the SwitchyOmega page, click New profile in the left-side navigation pane. In the New Profile dialog box, enter a profile name, such as SSH tunnel, in the Profile name field, select PAC Profile, and then click Create.
     4. Enter the following content in the PAC Script editor:

        function regExpMatch(url, pattern) {    
          try { return new RegExp(pattern).test(url); } catch(ex) { return false; }    
        }
        
        function FindProxyForURL(url, host) {
            // Important: replace 172.31 below with the proper prefix for your VPC subnet
        
            if (shExpMatch(url, "*localhost*")) return "SOCKS5 localhost:8157";
            if (shExpMatch(url, "*emr-header*")) return "SOCKS5 localhost:8157";
            if (shExpMatch(url, "*emr-worker*")) return "SOCKS5 localhost:8157";
        
            return 'DIRECT';
        }

     5. In the left-side navigation pane, click Apply changes to complete the configurations.
     6. Open Google Chrome. Click the SwitchyOmega extension. Then, select the created SSH tunnel.
     7. Enter http://<Name of the master node>:<Port number> in the address bar of the browser and press Enter to access a specific web UI.

        For more information about the ports of components, see Common ports of services. For more information about how to obtain the name of the master node, see Obtain the name of the master node.

        For example, enter http://emr-header-1:8088 in the address bar of the browser and press Enter to access the web UI of YARN.

Enable local port forwarding

You can use the local port forwarding method to forward data on a port of the master node to the local port and access the web application interface running on the master node. The SOCKS proxy is not required.

1. Run the following command on your on-premises server to create an SSH tunnel:
   • Use a key:

     ssh -i <Storage path of the key file> -N -L 8157:<Name of the master node>:8088 root@<Public IP address of the master node>

   • Use a username and a password:

     ssh -N -L 8157:<Name of the master node>:8088 root@<Public IP address of the master node>

   Parameter description:

   • -L: Local port forwarding is enabled. You can specify a local port to forward data to the remote port that is hosted on the on-premises web server of the master node.
   • 8088: the port that is used to access ResourceManager on the master node. You can replace this port as required.

     For more information about the ports of components, see Common ports of services. For more information about how to obtain the name of the master node, see Obtain the name of the master node.

   • 8157: Port 8157 is used in this example. You can replace this port with an unoccupied port on your on-premises server in actual configuration.
   • <Public IP address of the master node>: For more information about how to obtain the public IP address of the master node, see Obtain the public IP address of the master node.
   • <Storage path of the key file>: the path where the key file is stored.
2. Keep your on-premises server running. Open a browser, enter http://localhost:8157/ in the address bar of the browser, and then press Enter.

Common ports of services