devshell

#!/usr/bin/env bash

set -euo pipefail

script_dir=$(dirname $(readlink -f $0))
base_dir=$(git rev-parse --show-toplevel 2>/dev/null || pwd)

project_name="general"
default_variant="ubuntu"
default_container_name="none"
default_home_volume="none"
default_args=("/usr/bin/env" "zsh")
default_ro_paths=(".git" ".local")
default_masked_paths=()

variant=${DEVSHELL_VARIANT:-$default_variant}
dockerfile=Dockerfile.${variant}
container_name=${DEVSHELL_CONTAINER_NAME:-${default_container_name}}
home_volume=${DEVSHELL_HOME_VOLUME:-${default_home_volume}}
cache_enabled=${CACHE:-"yes"}

### Check dependencies
if (( BASH_VERSINFO[0] < 5 )); then
  echo >&2 "WARNING: Your bash version is quite old."
fi

required_tools=("docker" "jq" "sha256sum")
missing_tools=()
for tool in "${required_tools[@]}"; do
  if ! command -v "$tool" >/dev/null; then
    missing_tools+=("$tool")
  fi
done
if (( ${#missing_tools[@]} > 0 )); then
  echo >&2 "Please install the following and try again:"
  for tool in "${missing_tools[@]}"; do
    echo >&2 "* $tool"
  done
  exit 1
fi

### Figure out if we need to rebuild the docker image

image_source_files=(
  $dockerfile
  entrypoint.sh
  entrypoint-user.sh
)
image_source_hash=$(
  for file in ${image_source_files[@]}; do
    cat "$script_dir/$file"
  done | sha256sum
)
image_source_hash=${image_source_hash%% *}

image_name="${project_name}-devshell:${variant}"
need_to_build="yes"

if [[ $cache_enabled != "no" && -n $(docker images -q $image_name) ]]; then
  image_source_hash_label=$(
    docker image inspect $image_name | \
      jq -r '.[0].Config.Labels."org.opencontainers.image.devshell.source-hash"'
  )
  if [[ $image_source_hash_label == $image_source_hash ]]; then
    need_to_build="no"
  fi
fi

if [[ $need_to_build == "yes" ]]; then
  echo "Building docker image..."
  no_cache=$([[ $cache_enabled == "no" ]] && echo "--no-cache" || echo)
  docker build \
    $no_cache \
    --file "$script_dir/$dockerfile" \
    --build-arg SOURCE_HASH="${image_source_hash}" \
    --tag "$image_name" \
    "$script_dir"
fi

### Options

if [[ -v DEVSHELL_DOCKER_OPTS ]]; then
  docker_opts=($DEVSHELL_DOCKER_OPTS)
else
  docker_opts=("-i")
  if [[ -t 0 && -t 1 ]]; then
    docker_opts+=("-t")
  fi
fi

if (( $# > 0 )); then
  args=("$@")
else
  args=("${default_args[@]}")
fi

if [[ $container_name != "none" ]]; then
  container_id=$(docker container ls -q --filter=name=$container_name)
  if [[ -n $container_id ]]; then
    found_image_name=$(docker inspect $container_id --format="{{.Config.Image}}")
    if [[ $found_image_name != $image_name ]]; then
      echo >&2 "Running container \"${container_name}\" has a different image:" \
        "${found_image_name} vs ${image_name}."
      exit 1
    fi
  fi
fi

if [[ ${container_id:-} ]]; then
  exec docker exec "${docker_opts[@]}" "$container_id" /usr/local/bin/entrypoint.sh "${args[@]}"
else
  if [[ $container_name != "none" ]]; then
    docker_opts+=("--name" ${container_name})
  fi

  if [[ $home_volume != "none" ]]; then
    docker_opts+=("--volume" "${home_volume}:/home/user")
  fi

  if [[ ${DEVSHELL_SSH:-} == "yes" ]]; then
    if ssh_auth_sock=$(readlink -f ${SSH_AUTH_SOCK} 2>/dev/null); then
      docker_opts+=(
        "--volume" "${ssh_auth_sock}:/run/ssh-agent.sock"
        "--env" "SSH_AUTH_SOCK=/run/ssh-agent.sock"
      )
    else
      echo >&2 "DEVSHELL_SSH: Ensure that SSH_AUTH_SOCK is set. You may need" \
               "to set up ssh-agent."
      exit 1
    fi
  fi

  if [[ ${DEVSHELL_SUDO:-} == "no" ]]; then
    docker_opts+=("--security-opt" "no-new-privileges")
  fi

  if [[ ! -v DEVSHELL_RO_PATHS ]]; then
    ro_paths=("${default_ro_paths[@]}")
  else
    IFS=':' read -r -a ro_paths <<< ${DEVSHELL_RO_PATHS}
  fi
  for path_relative in "${ro_paths[@]}"; do
    path="${base_dir}/${path_relative}"
    if [[ -a $path ]]; then
      docker_opts+=("--volume" "${path}:${path}:ro")
    fi
  done

  if [[ ! -v DEVSHELL_MASKED_PATHS ]]; then
    masked_paths=("${default_masked_paths[@]}")
  else
    IFS=':' read -r -a masked_paths <<< ${DEVSHELL_MASKED_PATHS}
  fi
  for path in "${masked_paths[@]}"; do
    [[ "$path" != /* ]] && path="${base_dir}/${path}"
    if [[ -f $path ]]; then
      docker_opts+=("--volume" "/dev/null:${path}")
    elif [[ -d $path ]]; then
      docker_opts+=("--mount" "type=tmpfs,destination=${path}")
    fi
  done

  # Local ZSH config
  if [[ -d ${HOME}/.zprezto ]]; then
    docker_opts+=("--volume" "${HOME}/.zprezto:/usr/local/lib/prezto:ro")
  fi

  exec docker run --rm "${docker_opts[@]}" \
    --volume ${base_dir}:${base_dir} \
    --env TERM=${TERM} \
    --env DEVSHELL_VARIANT=${variant} \
    --env DEVSHELL_PROJECT_DIR=${base_dir} \
    "${image_name}" \
    "${args[@]}"
fi