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Introducing --chdir: Simplify Your Multi-Repo Workflows

· 6 min read
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We're excited to announce a new global flag that makes working with Atmos across multiple repositories and directories significantly easier: --chdir (or -C for short).

The Problem​

If you've ever worked with Atmos in a multi-repository setup or during development, you've probably faced these scenarios:

  • Development workflow: You're building a new Atmos binary and want to test it against your infrastructure repo without installing it globally
  • CI/CD complexity: Your build runs in one directory, but your infrastructure code lives elsewhere
  • Multi-repo operations: You need to quickly check configurations across different infrastructure repositories
  • Script complexity: Your automation scripts have to change directories manually, making them harder to read and maintain

Previously, you had to either:

  • Manually cd to each directory before running Atmos
  • Write wrapper scripts to handle directory changes
  • Modify your PATH or use absolute paths to atmos binaries
  • Copy binaries to specific locations

The Solution​

The new --chdir flag (and its short form -C) changes Atmos's working directory before any other operations, including configuration loading. This mirrors the familiar behavior of tools like git -C and make -C.

Basic Usage​

# Long form
atmos --chdir=/path/to/infrastructure describe stacks

# Short form (preferred for brevity)
atmos -C /infra terraform plan vpc -s prod

# Relative paths work too
atmos --chdir=../other-repo list components

Development Workflow​

Testing a development build against your infrastructure is now trivial:

# Build your changes
make build

# Point the dev binary at your infrastructure repo
./build/atmos -C ~/projects/my-infrastructure describe stacks

# No need to change directories or modify PATH
./build/atmos -C ~/projects/my-infrastructure terraform plan vpc -s dev

CI/CD Pipelines​

Your CI/CD workflows become cleaner and more explicit:

# Before: Manual directory management
cd /infrastructure
atmos terraform plan vpc -s prod
cd -

# After: Explicit and clear
atmos -C /infrastructure terraform plan vpc -s prod

Environment Variable Support​

For scripts and CI/CD environments, you can use the ATMOS_CHDIR environment variable:

export ATMOS_CHDIR=/infrastructure

# All atmos commands now run in that directory
atmos terraform plan vpc -s prod
atmos describe stacks
atmos list components

The CLI flag takes precedence over the environment variable, allowing you to override the default when needed:

export ATMOS_CHDIR=/default-infra

# Use the default
atmos describe stacks

# Override for specific command
atmos -C /other-infra describe stacks

How It Works with --base-path​

It's important to understand the difference between --chdir and --base-path:

  • --chdir: Changes the working directory (like running cd first)
  • --base-path: Overrides the Atmos project root (where atmos.yaml lives)

Processing Order​

  1. --chdir executes first, changing the working directory
  2. --base-path is then resolved relative to the new working directory
  3. All other configuration loading and operations proceed

Example​

# Change to /infra directory, then look for atmos.yaml in ./config subdirectory
atmos -C /infra --base-path=./config terraform plan vpc -s dev

# This is equivalent to:
# cd /infra
# atmos --base-path=./config terraform plan vpc -s dev

When to Use Each​

  • Use --chdir when you want Atmos to run as if you had changed directories first
  • Use --base-path when your Atmos project root is in a non-standard location
  • Combine them when your working directory and Atmos project root are in different places
# Just change working directory (atmos.yaml is in the root)
atmos -C /path/to/infra terraform plan vpc -s prod

# Just override project root (stay in current directory)
atmos --base-path=/custom/location terraform plan vpc -s prod

# Both: change directory AND override project root
atmos -C /infra --base-path=./custom terraform plan vpc -s prod

Real-World Examples​

Multi-Repo Infrastructure Management​

# Check production infrastructure
atmos -C ~/projects/prod-infra describe affected

# Compare with staging
atmos -C ~/projects/staging-infra describe affected

# All without leaving your current directory

Development and Testing​

# Test local changes against test environment
./build/atmos -C ~/infra terraform plan vpc -s test

# Once satisfied, use installed version for production
atmos -C ~/infra terraform apply vpc -s prod

Automated Scripts​

#!/bin/bash
# Script can stay in your tools repo while operating on infrastructure

INFRA_DIR="/path/to/infrastructure"

echo "Validating stacks..."
atmos -C "$INFRA_DIR" validate stacks

echo "Checking for drift..."
atmos -C "$INFRA_DIR" terraform plan vpc -s prod --detailed-exitcode

echo "Generating documentation..."
atmos -C "$INFRA_DIR" docs generate

Error Handling​

Atmos provides clear error messages when things go wrong:

  • Directory doesn't exist: Clear message with the path that was attempted
  • Path is a file, not a directory: Explicit error explaining the issue
  • Permission denied: OS-level error with context
  • Invalid path: Path resolution errors are caught and reported

Platform Compatibility​

The --chdir flag works consistently across:

  • Linux - All distributions
  • macOS - All versions
  • Windows - Native support

Both absolute and relative paths work as expected on all platforms, with proper path separator handling.

Technical Details​

For those interested in the implementation:

  • Execution order: --chdir → config loading → --base-path resolution → command execution
  • Path resolution: Relative paths are resolved from the current working directory
  • Symlinks: Symlinks to directories work correctly
  • Environment variable: ATMOS_CHDIR follows the same precedence rules as other Atmos env vars
  • Flag precedence: CLI flag > environment variable > current directory

Getting Started​

The --chdir flag is available starting in Atmos vX.X.X. To start using it:

# Upgrade to the latest version
brew upgrade atmos  # macOS
# or download from GitHub releases

# Start using the flag immediately
atmos --chdir=/your/infra describe stacks

# Or set it as an environment variable for your session
export ATMOS_CHDIR=/your/infra

Conclusion​

The --chdir flag is a small addition that makes a big difference in daily workflows. It removes friction from multi-repo operations, development workflows, and automation scripts.

We designed it to feel natural if you've used similar flags in other tools (git -C, make -C, tar -C), while integrating seamlessly with Atmos's existing flag system.

Try it out and let us know what you think! We'd love to hear how you're using it in your workflows.

Resources​

Have feedback or questions? Join our Slack community or open an issue on GitHub.