Template syntax

How {{env}}, {{input}}, {{vars}}, {{secrets}}, and {{nodes}} resolve at runtime

String fields in nodes (URLs, headers, bodies, conditions, set values, and output maps) support mustache-style tokens. The engine replaces each {{…}} before the node runs.

The previous node’s JSON is not a template scope. It is already the next node’s execute input — use JMESPath there (body.id, products[0]). See How flows work.

Five template roots. Merge also has source keywords previous / input / vars / node ids — those are not mustache scopes.

Scopes

Token	Source	Example
`{{env.KEY}}`	Environment `variables`	`{{env.API_BASE}}`
`{{secrets.KEY}}`	Secrets file for the selected env	`{{secrets.API_TOKEN}}`
`{{input.path}}`	Flow run input (CLI `--input` / Run panel)	`{{input.username}}`
`{{vars.key}}`	Variables set by `set` nodes	`{{vars.token}}`
`{{nodes.id}}`	Full output of a prior node	`{{nodes.login}}`
`{{nodes.id.path}}`	Nested field on a prior node output	`{{nodes.login.body.id}}`

Missing paths resolve to an empty string ("").

Run input vs wire vs `input` node

Need	Use
Field from Run panel / `--input` in a string	`{{input.email}}`
Put that payload on the wire for the next node	`input` node
Field from the last step inside extract/assert/json	JMESPath `body.id`
Field from a named earlier node in a string	`{{nodes.httpId.body.id}}`
Combine bags	`merge` `sources: ["previous", "input", …]`

Dot paths

{{input.profile.age}}
{{nodes.login.body.user.id}}
{{env.API_BASE}}

Examples

URL and headers

{
  "method": "GET",
  "url": "{{env.API_BASE}}/users/{{nodes.userId}}",
  "headers": {
    "Authorization": "Bearer {{secrets.API_TOKEN}}"
  }
}

JSON body as a string

{
  "method": "POST",
  "url": "{{env.API_BASE}}/users",
  "headers": { "Content-Type": "application/json" },
  "body": "{\"username\": \"{{input.username}}\", \"email\": \"{{input.email}}\"}"
}

Object body

{
  "body": {
    "username": "{{input.username}}",
    "token": "{{secrets.API_TOKEN}}"
  }
}

Conditions (`if`)

{
  "type": "if",
  "data": {
    "condition": "{{input.active}}",
    "checks": [{ "path": "status", "op": "gte", "value": 200 }]
  }
}

checks[].path is JMESPath on the wire (e.g. status after HTTP).

`set` variables

{
  "type": "set",
  "data": {
    "variables": {
      "greeting": "Hello {{input.username}}",
      "retryCount": 3
    }
  }
}

Template node vs `{{…}}`

{{…}} tokens — string substitution in templated fields.
template node — also supports Eta (<%= it.input.name %>, <%= it.previous %>) after mustache resolution. See template node.

JMESPath (wire, not mustache)

extract, transform, assert, and json query the previous node output with JMESPath:

Goal	Expression
HTTP body id	`body.id`
First product	`body.products[0]`
Nested name	`body.user.name`