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Tedge node-red plugin

Pre-requisites

You need to have node-red already installed on your device. If you don't already have it then check out the Node-RED documentation.

Plugin summary

Install/remove node-red projects on a device using thin-edge.io software management plugin.

Technical summary

The following details the technical aspects of the plugin to get an idea what systems it supports.
Languages shell (posix compatible)
CPU Architectures all/noarch. Not CPU specific
Supported init systems N/A
Required Dependencies -
Optional Dependencies (feature specific) -

How to do I get it?

The following linux package formats are provided on the releases page and also in the tedge-community repository:

Operating System Repository link
Debian/Raspian (deb) Latest version of 'tedge-nodered-plugin' @ Cloudsmith
Alpine Linux (apk) Latest version of 'tedge-nodered-plugin' @ Cloudsmith
RHEL/CentOS/Fedora (rpm) Latest version of 'tedge-nodered-plugin' @ Cloudsmith

What will be deployed to the device?

  • The following software management plugins which is called when installing and removing nodered projects via Cumulocity IoT
    • nodered - Deploy a project using the node-red project structure (e.g. git repository containing a flow)

Activating a project

Node-red supports deploying multiple projects to a device however only one project can be active at one time. The tedge-nodered-plugin supports installing multiple projects, and the active project can be controlled by a special (magic) package name

A project can be activated by using a special package name and version.

Name Version SoftwareType
active-project <project_name> nodered

The reasoning behind having the magic package was to allow users to deploy projects to devices and decide whether it should be activated or not. Sometimes not automatically activating a project can be useful if you want to download the project to all the devices but wait to activate it at a later point in time.

Plugin Dependencies

The following packages are required to use the plugin:

  • jq
  • curl
  • node-red
  • npm (requirement of node-red)

Known issues

  • Activating a new project for the first time does not seem to work for reasons unknown, however restarting the nodered service seems to fix this. The root cause should be investigated as it is probably a sign that an API call is missing or the install sequence is wrong.

Development

Start demo

  1. Start the demo

    just up

  2. Open the exposed container port http://localhost:1880

Stop demo

just down

Design

Proposed workflow of a node-red project

The following workflow details how node-red projects could be deployed to a fleet of devices. It shows the development process through to the deployment to devices.

  1. Create git repo for a node-red project (containing a flow)

  2. Build/test the flow using a github runner or run on a device

  3. Publish the flow to Cumulocity using go-c8y-cli to the software package (with new version)

  4. Manually create a bulk operation to deploy the new flow to the fleet of devices

Package format

Option1: Configuration file containing the URL of the project

A single file containing the git URL which can be used to clone the project on the device.

REPO=https://github.com/reubenmiller/nodered-demo.git

Option 2: Single tarball (tar.gz) file containing a snapshot of the project

The single tarball which contains the exported project's files.

  • flow.json

  • settings.js (used to parameterize the flow.json)

  • dependencies.txt (text file containing each dependency one per line) this will be used to install npm modules

  • version file containing the version of the snapshot on the first line

    1.0.0

Packaging a node-red project

Instructions how to create an offline installable node-red project. It will export a git project and create a tarball (.tar.gz) that can be used with this plugin.

Archive the full directory

COMMIT=$(git rev-parse --short HEAD);
BRANCH=$(git rev-parse --abbrev-ref HEAD);
VERSION="$BRANCH@$COMMIT";
ARCHIVE="$(basename $(pwd))__$VERSION".tar.gz;
tar cvzf "$ARCHIVE" .

Archive current branch

  1. Create an archive using git (requires a recent version of git which supports the --add-virtual-file flag)

    cd my-project
COMMIT=$(git rev-parse --short HEAD);
BRANCH=$(git rev-parse --abbrev-ref HEAD);
VERSION="$BRANCH@$COMMIT";
ARCHIVE="$(basename $(pwd))__$VERSION".tar.gz;
git archive --format=tar.gz --add-virtual-file=version:"$VERSION" -o "$ARCHIVE" HEAD;

  2. Create the software item and upload the version to the Cumulocity software repository

    c8y software create --name nodered-demo --description "Node red flow" --data softwareType=nodered

    Then add the version

    c8y software versions create --software nodered-demo --version "$VERSION" --file ./nodered-demo__master@32256bb.tar.gz

# Or using wildcards
c8y software versions create --software nodered-demo --version "$VERSION" --file ./nodered-demo__*@*.tar.gz

  3. Create an active flow software entry to control which item should be active. There should be one per flow

    c8y software create --name active-flow --description "Active node-red flow" --data softwareType=nodered
c8y software versions create --software active-flow --version "nodered-demo" --url " "

Uploading a project using an external URL

  1. Create a configuration file containing the url

    REPO=https://github.com/reubenmiller/nodered-demo

  2. Create a software version item in Cumulocity IoT

    c8y software versions create --software nodered-demo --version "latest" --file ./tests/testdata/nodered-demo.cfg

Future ideas

  • How to spawn to node-red instances to support applying multiple flows on the same device. Each instance must use a different port / service.