# `mix fly_deploy.blue_green`

Performs a blue-green deploy via peer nodes.

This is equivalent to `mix fly_deploy.hot --mode blue_green`. It builds
a full release tarball (beams, configs, NIFs, static assets) and triggers
each machine's PeerManager to boot a new peer with the new code, then
gracefully shut down the old peer.

## Quick Start

    mix fly_deploy.blue_green

    # Use staging config
    mix fly_deploy.blue_green --config fly-staging.toml

    # Pass Docker build arguments
    mix fly_deploy.blue_green --build-arg ELIXIR_VERSION=1.18.2

    # Preview without executing
    mix fly_deploy.blue_green --dry-run

## Options

Accepts all the same options as `mix fly_deploy.hot` except `--mode`:

  * `--config` - Path to fly.toml file (default: "fly.toml")
  * `--skip-build` - Skip building and use existing image (requires --image)
  * `--image` - Use specific pre-built image
  * `--build-arg` - Pass build-time variables to Docker (can be used multiple times)
  * `--dry-run` - Show what would be done without executing
  * `--force` - Override deployment lock (use with caution)
  * `--lock-timeout` - Lock expiry timeout in seconds (default: 300)

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*Consult [api-reference.md](api-reference.md) for complete listing*