Packaging a headless MCP tool-server (multi-profile) as a Margo application — Application Description questions

[zw008]

A spec question on the Application Description (margo.org/v1-alpha1), grounded in a concrete candidate app.

Industrial-AIOps (iaiops, MIT, on PyPI + the MCP Registry) is a headless, pure-Python OT diagnostics workload that runs as a governed MCP server — a vendor-neutral, read-first tap across ~14 field protocols (OPC-UA, Modbus, S7comm, EtherNet/IP, PROFINET-DCP, BACnet/IP, MTConnect, MQTT-Sparkplug, HART-IP, …) plus a cross-protocol RCA "brain", all exposed as MCP tools with audit / budget / risk-tier / undo governance. A site enables one profile selecting which connectors load.

I've drafted a margo.yaml to the v1-alpha1 schema — shape below:

apiVersion: margo.org/v1-alpha1
kind: ApplicationDescription
id: io-github-industrial-aiops-iaiops
deploymentProfiles:
  - type: compose
    id: iaiops-compose
    components:
      - name: iaiops
        properties: { packageLocation: <signed compose.tar.gz>, keyLocation: <pubkey> }
    requiredResources:
      cpu: { cores: 0.5, architectures: [amd64, arm64] }
      memory: 512Mi
parameters:
  profile:            # edition -> env var; SelectValidationSchema (fab|factory|process|building|water)
    value: factory
    targets: [{ pointer: IAIOPS_MCP, components: [iaiops] }]
  masterPassword:     # no secret-typed parameter in the spec yet -- see Q3
    targets: [{ pointer: IAIOPS_MASTER_PASSWORD, components: [iaiops] }]

Three questions:

1. Runtime shape — the app exposes an MCP stdio/socket tool surface rather than an HTTP UI. Does the Application Description care about the interface, or purely about container + config + lifecycle?
2. Profiles / variants — I've modeled the editions as one application with a profile parameter (SelectValidationSchema → IAIOPS_MCP env var). Is that the intended idiom, or would you expect N app packages (one per profile)?
3. Secret + least-privilege — v1-alpha1 seems to have no secret-typed parameter; how should a workload declare a secret param, plus "read-first, outbound-only to configured OT endpoints, no inbound"? Governance is core to this app.

Happy to open-source the full margo.yaml + a hardened container recipe as a worked example for a "governed, read-only OT tool app." Thanks!

[phil-abb]

I've answered the questions on Discourse: https://discourse.margo.org/t/governed-mcp-based-ot-diagnostics-as-a-margo-edge-application-reference-feedback/43/2?u=philip_presson_abb

This is where we'd like to keep public communication, so I'm closing this discussion thread. Please post follow-up questions on Discourse.