manage

#!/usr/bin/env bash

# A NixOps Wrapper for Git Projects
# ---------------------------------
#
# Repo: https://github.com/grafted-in/nixops-manager
#
# This tool is a simple wrapper around NixOps. The goal is to make it easier to use NixOps when you
# want to share your deployment state between members of a team.
#
# To achieve this, this wrapper gives every deployment as a separate state file which is placed
# in the same directory as this script. The files have the `.nixops` extension.
#
# You are expected to keep these files in version control. It's also *highly* recommended that you
# use a tool like git-crypt to keep them encrypted with this entry in .gitattributes:
#
#    *.nixops   binary filter=git-crypt diff=git-crypt
#
# This tool also enforces a per-repository version of Nixpkgs via a `nixpkgs-version.sh` file in the
# same directory as the script. This ensures that all users have a consistent version of NixOps and
# deploy a consistent set of packages to servers.
#
# Most commands work identically to NixOps. However, instead of specifying deployments with
# the `--deployment/-d` flag, you select a deployment in the first argument. In other words, instead
# of the normal NixOps usage of
#
#   nixops deploy -d stage --check  # Normal nixops usage.
#
# You'd run:
#
#   ./manage stage deploy --check   # Manage script usage.
#
# This assume there is a file ./stage.nixops where this state is being stored.
#
# Use `./manage --help` to see normal NixOps help.
# Use `./manage {deployment} .shell` to open a Nix shell where the environment is set up to use
# `nixops` directly with the same behavior as running `./manage` commands.

set -e

# Check for Nix tools.
command -v nix-shell >/dev/null 2>&1 || {
  nix_profile="$HOME/.nix-profile/etc/profile.d/nix.sh"
  if [ -e "$nix_profile" ]; then
    source "$nix_profile"
  else
    >&2 echo "Failed to find 'nix-shell' on PATH or a Nix profile to load. Have you installed Nix?"
    exit 1
  fi
}

here=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
repo_root=$(cd "$here" && git rev-parse --show-toplevel)  # Use Git to find repo root.

deployment="$1"
command="$2"
state_file="$here/${deployment}.nixops"

source "$here/nixpkgs-version.sh"

export NIX_PATH=nixpkgs="$nixpkgs_snapshot":"$repo_root":.
export NIXOPS_STATE="$state_file"
export NIXOPS_DEPLOYMENT="$deployment"

withNixops="nix-shell -p $nixops_version --run"

# Arg list trick:
# https://stackoverflow.com/questions/3104209
# ARGS=$(printf "%q"" " "$@")

if [[ $deployment == --* ]]; then
  ARGS=$(printf "%q"" " "$@")
  $withNixops "nixops $ARGS"
  exit $?
elif [ "$command" == ".shell" ]; then
  nix-shell -p "$nixops_version"
elif [ ! -e "$state_file" ] && [ "$command" != "create" ]; then
  >&2 echo "You're trying to use a deployment that doesn't exist yet. Try running $0 $deployment create"
  exit 1
elif [ -e "$state_file" ] && [ "$command" == "create" ]; then
  >&2 echo "You're trying to create a deployment that already exists."
  exit 1
else
  ARGS=$(printf "%q"" " "${@:2}")
  $withNixops "nixops $ARGS"
fi