Resources

Resources are files an integration imports alongside its config: .env-convention files that feed the environment, and template files that flows render. Declared under resources:, they load when the config loads, so a missing or malformed file fails at deployment.

Declaring resources

env:
  - name: GREETING
    required: true          # supplied by the .env.dev resource below

resources:
  env:
    - .env.dev              # merged into the runtime environment
  templates:
    - resource: templates/welcome.tmpl
      as: welcome           # short alias for blocks and CEL

Resource paths resolve relative to the config directory.

Env resources

resources.env lists .env-convention files (KEY=VALUE lines, # comments) combined into the runtime environment in order: a later file overlays an earlier one, and all overlay the built-in ./.env chain. A missing env resource is skipped silently; a required variable it was supposed to supply still fails the load. See Environment and Configuration for the full precedence.

GREETING=Hello from .env.dev

Template resources

resources.templates declares the template files the config renders, each named by file (resource) and optionally by a short alias (as); without an alias the template is referenced by its path. Every declared template is parsed at load time. Templates are plain text with embedded {{ CEL }} expressions evaluated against the current message, with body, vars, env, and now available:

{{ env.GREETING }}, {{ body.name }}!

A span is ordinary CEL, so every custom function works inside one, including templateResource, which lets a template pull in another:

{{ templateResource("header") }}
<p>{{ toJson(body) }}</p>

Nesting is capped at 8 levels, so a template that renders itself fails with a clear error.

Rendering a template

There are two ways to render a declared template.

The template-resource block

The block renders a template against the current message and writes the result to a variable (target) or, when target is empty, to the message body:

flows:
  - name: greet
    process:
      - type: template-resource
        settings:
          id: welcome          # the `as` alias (or the resource path)
          target: rendered     # write to vars.rendered; empty replaces the body

For non-JSON output (HTML, XML, CSV) set rawBody: true and a contentType. The rendered text becomes a raw-content body {contentType, rawData}, which the HTTP source serves with that Content-Type instead of JSON:

resources:
  templates:
    - resource: templates/page.tmpl
      as: page

flows:
  - name: page
    source:
      connector: api
      type: http
      settings:
        path: /page/{name}          # {name} -> vars.name
    process:
      - type: template-resource
        settings:
          id: page
          rawBody: true
          contentType: text/html; charset=utf-8

The templateResource() CEL function

Inside any expression, templateResource("alias") renders the template against the current message and returns the text, for when the rendered string is one piece of a larger value:

- type: set-payload
  settings:
    value: |
      {
        "viaBlock": vars.rendered,
        "viaCel": templateResource("welcome")
      }

Pick the block when the rendered text is the output, and the function when composing it into something else.

Where templates show up next

An ai-agent's skills and an mcp-router's resources and prompts are also declared template resources. On the platform, resources are managed per integration; see Resources and Secrets.