node-red-contrib-gatekeeper

A tiny Node-RED node that opens or closes the gate for passing messages forward.
You choose a property (from msg, flow, global, env, or a jsonata expression).
If that value is true (or the string "true"), the gate closes (message dropped).
Otherwise, the gate opens and the message continues.

Features

• ✅ Simple allow/deny logic in one node
• ✅ Supports msg, flow, global, env, or jsonata
• ✅ Clear status: open (green) / closed (red)
• ✅ No external deps

Install

From your Node-RED user directory (~/.node-red):

npm install node-red-contrib-gatekeeper

Or via Manage palette → Install → search for node-red-contrib-gatekeeper.

Usage

1. Drag Gatekeeper into your flow.

2. Set Property to check:

   • msg/flow/global/env: provide the property/key (e.g., payload, allow, FEATURE_FLAG)
   • jsonata: provide a JSONata expression (e.g., payload.allow = true)

3. If the evaluated value is true or the string "true" → gate closed (message not forwarded). Anything else → gate open (message forwarded).

Status

• green dot — open (message passes)
• red dot — closed (message blocked)
• red ring — error

Properties

| Field | Type | Description | | ------------ | --------------------------- | ------------------------------------------------------------------------ | | Name | string | Optional label shown under the node. | | Property | msg/flow/global/env/jsonata | The value to check. If it resolves to true (or "true"), gate closes. |

Examples:

• msg + payload → checks msg.payload
• flow + allow → checks flow.get("allow")
• global + feature.enabled → checks global.get("feature.enabled") (if you store an object)
• env + FEATURE_FLAG → checks process.env.FEATURE_FLAG
• jsonata + payload.level > 10 → evaluates expression on the incoming msg

Example flows

1) Simple boolean in msg.payload

[
  { "id":"inject1","type":"inject","name":"allow=false","props":[{"p":"payload"}],"payload":"false","payloadType":"bool" },
  { "id":"gate1","type":"gatekeeper","name":"Gate","property":"payload","propertyType":"msg" },
  { "id":"debug1","type":"debug","name":"Passed","complete":"true" }
]

• payload=false → gate open → message passes
• Set payload=true → gate closed → message dropped

2) JSONata condition

[
  { "id":"inject2","type":"inject","name":"payload={ level: 12 }","props":[{"p":"payload"}],"payload":"{\"level\":12}","payloadType":"json" },
  { "id":"gate2","type":"gatekeeper","name":"Level Gate","property":"payload.level > 10","propertyType":"jsonata" },
  { "id":"debug2","type":"debug","name":"Passed","complete":"true" }
]

• Expression resolves to true → gate closed (blocked)
• Change to payload.level > 99 → resolves false → gate open

Notes

• The node treats boolean true and string "true" as closed; everything else is open.
• With jsonata, the expression is evaluated against the current msg. Any exception is shown as error status.

License

MIT © AIOUBSAI