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ManageYourDevices.md

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Node.js microServiceBus.com

Manage your devices

Life is good when everything is up running and performing as expected, -Not so good when it fails, but much worse if you can't solve it remotely...

In the first lab we learned how to build a solution. In this lab we're going to look into managing and trouble-shooting.

Scenario

The scenario we're going to work with, is that the data you sent upstream in the first lab, is also being sent to a back-end system. The system owner of that back-end system has filed an issue saying they get the wrong information in the computer field from your reading. This is critical for their system to work:

Drawing

We are going to follow a series of steps to identify and resolve this issue:

Step 1 - Enable tracking

No payload-data ever passes microServiceBus.com unless the user enables tracking. Tracking is a tool that provides us with insight into the process and helps us identify the problem.

  1. Navigate to the Nodes page, and click the Tracking toggle-button for your Node. Observe in the console/terminal window that is says: mSB: Tracking: enabled.
  2. Navigate to the Management page, and click Tracking from the top menu.
  3. Expand the "Detailed search" pane by clicking on it. Click the "Add new record" button. Let the Property field be "Node" and set the "Value" field to the name of your Node and click Search.
  4. Click View details of second or third records in the list.

Tracking details are being streamed as they are executed and if you take the first in the list (the last event), it might not be competed, hence you might not get all the details.

  1. The Tracking Details window shows you all the events that has happened on this instance of the flow. -Click the View itinerary button for the Completed event.
  2. The Itinerary window shows you where in the Flow you are, what the message looks like along with variables and properties. - Click on the Message tab.

From what we can see, the computer field seems to be set to the platform rather than the name of the computer. In this case it's tempting to just go straight to the Script page, but we're going to pretend this is a more complex issue.

Step 1 - Remote debugging

Remote debugging is a very powerful option which can provide you with valuable insight to your Service. You can also run profiling on your Node to find potential memory leaks or high memory/CPU contention.

  1. Navigate to the Node page. Click the ACTIONS button and select Debug, then click START DEBUG.

The Node will now get restarted in "Debug mode". Wait a few seconds and you'll be presented a debug URL.

IMPORTANT! Due to some updates in Chrome, you will not be able to use the URL directly in Chrome.

  1. Copy the IP and port from the URL.

E.g chrome-devtools://devtools/bundled/js_app.html?experiments=true&v8only=true&ws=192.168.1.20:9231/89c91da1-a799-42db-8c1f-5956367ead8d

  1. Open a new tab and type:
chrome://inspect
  1. Click the Configure button and paste the IP and port. Click Done
  2. Wait a few seconds for the debugger to attach then click "Sources" from the menu.
  3. In the left pane, navigate to your Service. Should be under file://[HOME directory]/microServiceBus/services/[Name of your service].js. Double-click to open.
  4. Set a breakpoint at approx row 36 (var computer = os.platform();) by clicking the row number in the gutter of the editor. Wait a few seconds and the breakpoint should hit.
  5. Step over the line by hitting F10, and hover the computer variable and view the value.

The problem is that you use os.platform() rather than os.hostname(). Easy enough to fix. Let's head over to the Scripts & Services again. -But first, in Node page, make sure to stop debugging by click on the STOP DEBUG button in the debugging window before you proceed. Go back to the Chrome Debug Tool and hit the resume button.

Fix issue and Restart Node

  1. Navigate to the Scripts & Services page by hitting CTRL + R to get the command prompt. Type "scripts" and hit Enter.
  2. Open your Service and edit the script. Replace var computer = os.platform(); with var computer = os.hostname();.
  3. Hit CTRL + R again, and type restart [YOUR NODE] Eg.:
restart device1
  1. Switch to the console/terminal window to see the Node restarting and make sure it sends the correct data.

Other management task...

There are times where issues might not reside in your application, but in other services or resources on your device. In such cases you need shell access to properly investigate and track down the issue.

There are two ways to open an SSH session into the device.

Remote terminal

Provided you are either an Owner of the Organization or the "Allow everyone in the team to use remote terminal" option has been enabled, you can access a device terminal through the ACTION menu in the Node page.

  1. From the ACTION menu onn your Node, click Open terminal.

This step will cause the Node to download some additional packages. If the terminal window is not opening right away, just give it a couple of minutes and try again.

IMPORTANT! Remote terminal requires Python to be installed on the device.

Direct access

Direct access require the microservicebus-dam (Device Access Manager) to be installed. The main difference from using the Remote terminal is that you will access the Node using your own account, rather than as the service user running the Node agent.

Although this package is available on NPM, we will only cover the process in this lab.

To get direct access you need to create a SSH user. This can be done on your account page, where you can add and manage your keys in the SSH Keys tab. Once the user is created, you can grant yourself access to the Node from the ACTION menu in the Node page.

Although the microservicebus-node process is very resilient, -IF it should crash and for any reason not recover, the Direct access is your only remote option.

Well done, you've finished lab 2.

Back to main page.