---
id: sceptre-cmd-resolver
version: "2.0.0"
license: Apache2
license_treatment: permissive
maintenance: active
---

# sceptre-cmd-resolver — Sceptre resolver to execute generic shell commands

License: permissive · Maintenance: active · Downloads: 115.5K/mo

## What it is and what it does

This is a plugin for Sceptre, the CloudFormation orchestration tool, that lets you use the `!rcmd` YAML tag to execute arbitrary shell commands and inject their output as CloudFormation stack parameters. Instead of hardcoding values, you can run commands at deploy time—pulling secrets from Vault, querying AWS APIs for the latest AMI IDs, reading files, or piping output through standard Unix tools like jq and grep.

The resolver runs commands with the same AWS profile and credentials that Sceptre uses, and you can override the profile, region, or IAM role on a per-parameter basis. This makes it useful for dynamic lookups that depend on your deployment environment, secrets management integration, or any external data source accessible via the command line.

Use it for:

- Fetch the latest Ubuntu AMI ID from AWS Systems Manager Parameter Store at stack deployment time
- Retrieve database passwords or API keys from Vault or similar secret management tools
- Read configuration or secrets from local files using cat, jq, or other Unix utilities
- Query AWS APIs (S3, EC2, etc.) to populate stack parameters with live data
- Generate deployment metadata like timestamps or usernames to include in stack tags or comments

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

A Sceptre resolver plugin that executes shell commands to dynamically resolve CloudFormation stack parameters at deployment time.

Yes, if you use Sceptre and need to inject dynamic values into CloudFormation stacks at deploy time. The low install friction, active maintenance, permissive license, and zero known vulnerabilities make it safe to adopt. The single dependency on sceptre itself keeps the footprint minimal. Install it when you want to move beyond static parameters and integrate external tools or APIs into your infrastructure-as-code workflow.

## Install

pip install sceptre-cmd-resolver
uv add sceptre-cmd-resolver
poetry add sceptre-cmd-resolver

## Installing sceptre-cmd-resolver

Before you install: Low friction install with a single runtime dependency on sceptre. The package is actively maintained with recent commits and supports Python 3.7 through 3.10.

License in practice: Apache2 permissive license allows use in commercial and proprietary projects without significant restrictions.

Quickstart:

pip install sceptre-cmd-resolver

# In a Sceptre config YAML file:
parameters:
  DatabasePassword: !rcmd cat .env/password
  LatestAmiId: !rcmd aws ssm get-parameters --names /aws/service/canonical/ubuntu/server/20.04/stable/current/amd64/hvm/ebs-gp2/ami-id --query 'Parameters[0].[Value]' --output text

Verify before relying:

- Whether the resolver works reliably with Windows PowerShell or only Unix-like shells
- Performance characteristics when resolving many parameters or executing long-running commands
- Whether environment variables and AWS credentials are properly inherited during command execution

## Package facts

- License: Apache2 (permissive)
- Python support: unspecified
- Install friction: low
- Maintenance: active
- Downloads: 115.5K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

sceptre resolver shell command, dynamic parameter resolution cloudformation, sceptre plugin command execution, yaml tag shell command resolver, runtime parameter injection sceptre, bash command cloudformation parameters, sceptre rcmd tag resolver, cloudformation, infrastructure-as-code, sceptre-plugin

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