#  Local Stacks

A Stack defines a set of platform configuration options that will get applied to each Node-RED instance when it is created.

For the Local deployment model, this covers two things:

• memory - the value to apply (in MB) to the Node.js max-old-space-size option. This defines the point where Node.js will start freeing unused memory. It is not a hard limit - Node-RED's memory usage will not be capped - but this is useful when running on a memory constrained device such as a Raspberry Pi. Recommended minimum 256.
• nodered - the version number of Node-RED to use. This should match the value used in the steps following.

The FlowFuse installer will create a default stack using the latest stable release of Node-RED.

The stacks are stored under /opt/flowforge/var/stacks or c:\flowforge\var\stacks on Windows.

#  Creating a Stack

When a new version of Node-RED is released, it can be added to your FlowFuse platform by creating a new stack.

For a local install there are two steps required:

1. Install a new Node-RED version

   In the FlowFuse Home directory, run the provided install script. You must provide the full Node-RED version number, eg 3.0.2, or use latest to install the most recent stable version.

   Linux/Mac:

   cd /opt/flowforge
   ./bin/ff-install-stack.sh 3.0.2

   Windows

   cd c:\flowforge
   bin\ff-install-stack.bat 3.0.2

2. Creating the Stack

   Log into the FlowFuse platform as an administrator. Navigate to the Admin Settings -> Stacks section.

   If this new stack should be offered as a direct upgrade of an existing stack, select the 'Create new version' option from the dropdown menu of the stack you want to replace. Node-RED instances that use the old stack will offer the new stack as a one-click upgrade option.

   Alternatively, click 'Create stack' to create an entirely new stack.

   When prompted for the Node-RED version, provide the exact version that was installed. For example, if you ran the script with latest and it resulted in 3.0.2 being installed, you should enter 3.0.2. This must match the directory name created in your stacks directory.

#  Development Only

If you are developing FlowFuse having checked it out from GitHub then you can run the following command in the repository root to install a stack:

npm run install-stack --vers=3.0.2