NOTE
StrongLoop Arc and slc are no longer under active development, and will soon be deprecated. Arc's features are being included in the IBM API Connect Developer Toolkit: Please use it instead.
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With Arc, you can manage applications running under control of StrongLoop Process Manager on multiple server hosts and configure an Nginx load balancer to route traffic to the hosts.

Prerequisites

Install and run StrongLoop Process Manager on each remote host where you want to run applications.  See Setting up a production host for details.

If you want to use an Nginx load balancer (optional), see Configuring Nginx load balancer for setup instructions.

Adding hosts

Click Process Manager in module picker to display Arc Process Manager:

The page lists all the known hosts running StrongLoop PM.

To add a new host:

  1. Click Add PM Host.

  2. Enter the fully-qualified domain name of the host, or select from the list of previously-used hosts.

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    Make sure you enter only the host name. Don't include "http://".
    For example, to connect to a Process Manager running on the local system, just enter "localhost", not "http://localhost". 

  3. Enter the port number on which StrongLoop PM is running on the host. 
    App Status for the host displays “Inactive.” 
  4. Click Activate to connect to Process Manager on that server.

Once the host has been found, App Status changes to “Active”, and the Processes column lists the number of processes running on the host and their process IDs.

The name of the app running on the host appears in the header.

  • The first PM Host activated will set the application for the Process Manager.  All subsequent PM Hosts added MUST be running the same application and version.  The application and version are read from the Node application's package.json file.

  • Click the context menu button next to the app name, to display controls for managing the app (Start, Stop, and Restart).

Deleting a host

To delete a host, highlight the row by clicking on the row in a non-input area: A “delete” button (x) appears at the end of the row.  Click (error) to delete the host from the list.

Deleting a host here simply removes it from Arc Process Manager; it does not shut down any processes or services on the host.

Adding a load balancer

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Using an Nginx load balancer is optional. StrongLoop integrates with Nginx and Arc provides an Nginx Controller.

You can use a different load balancer or none at all, but in that case you are responsible for routing traffic to your hosts appropriately.

Once you have installed and configured Nginx and the StrongLoop Nginx Controller, add the load balancer in Arc Manger.

Click Load Balancer in the Arc Process Manager module:

Enter the host name and port number where the StrongLoop Nginx controller is listening for control messages, then click Save.  These are the hostname and port specified with the -c option to the sl-nginx-ctl and sl-nginx-ctl-install commands.  See Managing multi-server apps (Adding a load balancer) for more information.

NOTE: You must have already installed and configured the Nginx load balancer and StrongLoop Nginx controller on the host.  See Configuring Nginx load balancer for more information.

 

Once you've add an Nginx load balancer as shown above, it will automatically distribute client requests evenly to your application (API) running under StrongLoop Process Manager on multiple hosts.  You can subsequently add additional hosts, and the configured load balancer will then route requests to the new hosts as well.

Controlling applications

Click  next to a Process Manager instance to control the application that Process Manager is running.

On the menu that appears, click:

  • Stop to stop the application running in that Process Manager.
  • Restart to restart the application; this is a "hard restart" that will stop and then start all the application worker processes.  If changes were done to the application's configuration, the new configuration settings would take affect.
  • Cluster-restart to perform a "rolling restart" of the application; this enables you to restart the application with zero downtime with the current application configuration.
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When you re-deploy an application, StrongLoop Process Manager will automatically perform a rolling restart so that the application is updated with no downtime. You don't have to manually restart it.

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