communication-keys/bin/update_sops.sh

#/usr/bin/env bash
# Purpose: manage .sops.yaml based on gpg keys in the same dir _and_ verify correct configuration
set -euo pipefail

function fn_gpg_extract_fpr(){
  gpgkeyfile=$1;shift;
  # fingerprint
  # caveat: restrict to netgo.de email, use-case:
  # uid ... <...@mehrwerk.net>
  # uid ... <...@netgo.de>
  # fancy gpg src: https://unix.stackexchange.com/a/731872
  fpr="$(gpg --show-keys --list-options show-only-fpr-mbox "${gpgkeyfile}" | grep '@netgo.de' | awk "{print \$1}")"
  echo "${fpr}"
}

function fn_gpg_extract_uid(){
  gpgkeyfile=$1;shift;
  # user id
  # caveat: restrict to netgo.de email, use-case:
  # uid ... <...@mehrwerk.net>
  # uid ... <...@netgo.de>
  # fancy gpg src: https://unix.stackexchange.com/a/731872
  uid="$(gpg --show-keys --with-colons "${gpgkeyfile}" | awk -F':' '$1=="uid" {print $10}' | grep '@netgo.de')"
  echo "${uid}"
}

function fn_sops_locate_config_in_git_repo(){
  # Returns path sops config to be updated; defaults to returning "$(git rev-parse --show-toplevel)/.sops.yaml"
  # sops locates config by recursively walking _up_ the tree from the execeution dir context,
  # + _but_ does not have a mechanism to update the sops config
  # This function does the same in order to locate the correct sops config to update

  # starting dir, default: PWD. Note: 'realpath' to normalise the dir
  start_dir="$(realpath "${1:-"${PWD}"}")";
  stop_dir="$(git rev-parse --show-toplevel)"
  >&2 echo "# ---"
  >&2 echo "# start_dir: "${start_dir}""
  >&2 echo "# stop_dir:  "${stop_dir}""

  # BEGIN
  search_dir="${start_dir}"
  contender="${search_dir}/.sops.yaml"
  # base case - located the file OR stopping condition - at top of repo
  if [[ -e "${contender}" ]]; then
    >&2 echo "# BASE CASE: found ${contender}"
    echo "${contender}"
  elif [[ "${search_dir}" == "${stop_dir}" ]]; then
    >&2 echo "# STOPPING CONDITION: no sops config found, suggesting: ${contender}"
    echo "${contender}"
  else
    >&2 echo "# walk up one dir..."
    fn_sops_locate_config_in_git_repo "$(dirname "${search_dir}")"
  fi
}

function fn_sops_generate_config(){
  # sops.yaml doc: https://github.com/getsops/sops?tab=readme-ov-file#using-sops-yaml-conf-to-select-kms-pgp-and-age-for-new-files
  # CAVEAT: dirty hacks, as DRY as feasible within bash

  # hack: 2D list workaround, i.e. difficult to have list-of-lists
  fpr_list=()
  uid_list=()
  type_list=()
  for gpgkeyfile in *automation*gpg.pub; do
    type_list+=( "autom" )
    fpr_list+=( "$(fn_gpg_extract_fpr "${gpgkeyfile}")" )
    uid_list+=( "$(fn_gpg_extract_uid "${gpgkeyfile}")" )
  done
  for gpgkeyfile in $(ls *gpg.pub | grep -v automation); do
    type_list+=( "human" )
    fpr_list+=( "$(fn_gpg_extract_fpr "${gpgkeyfile}")" )
    uid_list+=( "$(fn_gpg_extract_uid "${gpgkeyfile}")" )
  done


  # header
  echo "# Fingerprint | User Type | User ID"
  # entries/rows
  for ind in "${!fpr_list[@]}"; do
    printf "# %s | %s | %s\n" \
      "${fpr_list[${ind}]}" \
      "${type_list[${ind}]}" \
      "${uid_list[${ind}]}"
  done
  echo "# keys in https://git.dev-at.de/smardigo-hetzner/communication-keys"

  cat <<EOM
creation_rules:
  # list of keys for encryption in stage
  - pgp: >-
EOM

  # all but last line get comma
  ind_2nd_last=$((${#fpr_list[@]} - 1))
  for fpr in ${fpr_list[@]:0:${ind_2nd_last}}; do
    echo "      ${fpr},"
  done
  # last line no comma
  # echo "      ${fpr_list[-1]}," # requires bash v4.1
  echo "      ${fpr_list[${ind_2nd_last}]}"
}

fn_sops_updatekeys_and_verify(){
  # call 'sops updatekeys' and dump contents of file so end user can visually verify functionality
  sops_enc_file="${1}";shift;
  # update keys in secrets file
  test -e "${sops_enc_file}" || exit 1

  # "update the keys of SOPS files using the config file"
  sops updatekeys "${sops_enc_file}"

  # verify: dump secrets, GPG_TTY src: https://www.varokas.com/secrets-in-code-with-mozilla-sops/
  GPG_TTY=$(tty) sops -d "${sops_enc_file}"
}

function main(){
  if [[ ! -n "${@}" ]]; then
    # if empty args, remove
    shift
  fi
  # "anchor" for actions relevant to this script
  repo_root="$(realpath $(dirname "${BASH_SOURCE[0]}")/..)"
  # OPTIONS: ARGPARSING and VALIDATION
  # assume location of script as running directly from repo with keys (instead of as a standalone packaged tool)
  keyfiles_dir="${repo_root}"
  # assume location of secrets config file in pwd
  sops_config_dir="${PWD}"
  # path to group definitions
  groups_def_dir="${repo_root}/groups"
  # optional:
  opt_list_groups=0
  # optional: specify "groups"
  groups_list=()
  # optional: secrets files to be updated
  secrets_file_list=()

  while (( $# >= 1 ));do
    cur="${1}";
    case $cur in
      # ARGS: print this help
      -h|--help) echo "# ARGUMENTS:"; grep -A 1 '# ARGS:' "${BASH_SOURCE[0]}"; exit 0 ;;
      # ARGS: dir containing gpg keyfiles
      -k|--key|--keyfiles) keyfiles_dir="${2}"; shift ;;
      # ARGS: dir containing .sops.yaml (sops config file)
      -c|--config_dir) sops_config_dir="${2}"; shift ;;
      # ARGS: [optional] show list of groups and exit
      -lg|--list_groups) opt_list_groups=1 ;;
      # ARGS: [optional] [list] specify "groups" which correspond to e.g. job groups, projects, etc
      -g|--group) groups_list+=( "${2}" ); shift ;;
      # ARGS: [optional] [list] specify files containing sops-encrypted secrets
      -s|--secrets_file|-f|--file) secrets_file_list+=( "${2}" ); shift ;;
      # ARGS: [optional] [list] specify files containing sops-encrypted secrets
      *) secrets_file_list+=( "${cur}" )
    esac
    shift;
  done

  # Resolve Parameters
  # ... i.e. combine,override,etc options which interact
  if [[ "${#groups_list[@]}" -eq 1 ]]; then
    # simply change keyfiles_dir to the "groups" dir
    keyfiles_dir="${groups_def_dir}/${groups_list[0]}"
  elif [[ "${#groups_list[@]}" -gt 1 ]]; then
    >&2 echo "# ERROR: only specify one group"
    exit 1
  fi

  # VALIDATE INPUTS
  keyfiles_dir="$(realpath "${keyfiles_dir}")"
  test -d "${keyfiles_dir}" || (echo "E: specify dir containing keyfiles; invalid dir: '${keyfiles_dir}'" && exit 1)
  sops_config_dir="$(realpath "${sops_config_dir}")"
  test -d "${sops_config_dir}" || (echo "E: specify dir containing .sops.yaml, invalid dir: '${sops_config_dir}'" && exit 1)
  sops_config="${sops_config_dir}/.sops.yaml"
  # locate appropriate sops config if default assumption not found
  if [[ ! -e "${sops_config}" ]]; then
    # dev note: '2> /dev/null' to disable debug output
    sops_config="$(fn_sops_locate_config_in_git_repo 2> /dev/null)"
  fi
  if [[ "${#secrets_file_list[@]}" != "0" ]]; then
    for secrets_file in "${secrets_file_list[@]}"; do
      test -e "${secrets_file}" || (echo "E: could not locate file with secrets, tried: ${secrets_file}" && exit 1)
    done
  fi
  # /VALIDATE INPUTS
  # /OPTIONS: ARGPARSING and VALIDATION

  # BEGIN
  if [[ "${opt_list_groups}" -eq 1 ]]; then
    # list available groups and exit
    pushd "${groups_def_dir}" > /dev/null 2>&1
    >&2 echo "# INFO: listing groups"
    ls -1d *
    exit 0
    popd > /dev/null 2>&1
  fi

  # UPDATE SOPS CONFIG

  # update sops config
  # TODO: remove the 'pushd;popd' workaround and make the functions aware of the dir being read
  pushd "${keyfiles_dir}" > /dev/null 2>&1
  (fn_sops_generate_config) > "${sops_config}"
  popd > /dev/null 2>&1

  # VERIFY
  if [[ "${#secrets_file_list[@]}" != "0" ]]; then
    # import keys
    pushd "${keyfiles_dir}" > /dev/null 2>&1
    gpg --import *.gpg.pub
    popd > /dev/null 2>&1
    # update
    for secrets_file in "${secrets_file_list[@]}"; do
      fn_sops_updatekeys_and_verify "${secrets_file}"
    done
    echo "# SUCESS: all users with keys in this dir should have functional keys"
  else
    echo "# WARN: no secrets file passed in, make sure to call 'sops updatekeys' on secrets files"
  fi
}

# pass-through, set default value
main "${@-}"
exit