update_modules

#!/usr/bin/env bash

# A script for atomically updating the module files (via symlinks), without tempting people to modify them in place.
#
# by Ian Kirker, 2015
#
# Updated user detection stuff - OK, 20160225

moduledirs_path=/shared/ucl/apps
become_path="$(command -v become  2>/dev/null)"
ops_user=ccspapp

# OK what we want to do:

# 1 am I ccspapp?
# 2 am I in ccsprcop
# 3 if 2, does become exist?

if [ "$(whoami)" == "${ops_user}" ]; then
  echo "I am ops user ${ops_user}.  No need to use become."
elif (id -Gn | grep -v '\bccsprcop\b' >/dev/null 2>/dev/null); then
  echo "Error: user should be in ccsprcop group to use this script." >&2
  exit 1
elif [ ! -x "$become_path" ]; then
  echo "Error: No become path provided." >&2
  exit 3
else
  echo "Becoming ${ops_user} and re-running..." >&2
  if [[ "${0:0:1}" != "/" ]] && [[ "${0}" =~ ^[^\ ]*/ ]]; then
    echo "Warning: relative paths will not work when this script has to change user" >&2
  fi
  $become_path $ops_user <<EOF
  $0 "$@"
EOF
  exit
fi

scriptname="$(basename "$0")"
usage="
Usage: $scriptname [-h] [-f|-i] [-r]

    -h  Prints this help
    -f  Force update even if it would be the same
    -i  Do not treat it as an error if the update would be the same
    -k  Do not remove old module trees after update

Branches:
    If a file named 'modulefiles_branch_override' exists in the target
     directory, it will be read and its contents used as the name of the
     branch to check out from the modulefiles repository.
"

# Mode defaults
force_update="n"
idempotent="n"
remove_old_mfs="true"

# Parse options
while getopts ":hfik" opt; do
  case ${opt} in
    h )
        printf "%s" "$usage"
        exit 0
    ;;
    f )
        ## Force mode -- deploys even if the current deployment is the same as the most recent
        force_update="y"
    ;;
    i )
        ## Idempotent mode -- does not treat it as an error if the current deployment is the same as the most recent
        idempotent="y"
    ;;
    k )
        ## Keep module_dirs older than 7 days after deployment -- default is to remove them
        remove_old_mfs="false"
    ;;
    \? ) 
        printf "%s" "$usage"
        exit 2
      ;;
  esac
done


# Don't try to continue if something breaks
set -e

cd $moduledirs_path

if [[ ! -L "modulefiles" ]]; then
  if [[ "$force_update" != "y" ]]; then
    echo "Warning: this directory does not contain an existing modulefiles symlink. Attempting to run this script here may not do something sensible. Use \"-f\" to force run anyway."
    exit 2
  fi
  if [[ -d "modulefiles" ]]; then
    echo -e "Warning: an existing modulefiles directory is present. \n This script will attempt to move it out of the way, but this operation is not atomic and module accesses happening during the (hopefully very quick) transition may fail." >&2
    RENDIR=modulefiles_prevcs_$(date +%Y-%m-%d)
    mv -bv modulefiles "${RENDIR}" && ln -Tfs "${RENDIR}" modulefiles
  fi
fi


# Repo config info

branch="master"
repo_url="https://github.com/UCL-RITS/rcps-modulefiles.git"

override_file="$moduledirs_path/modulefiles_branch_override"
if [[ -r "$override_file" ]]; then
    echo "Found branch override file, reading..." >&2
    branch="$(tr -d '\n' <"$override_file")"
    echo "Set branch to: $branch" >&2
else
    echo "No branch override file found, using default: $branch" >&2
fi

echo "Getting latest commit hash for ${branch} branch..." >&2
latest_sha=$(git ls-remote --exit-code "${repo_url}" "${branch}" | cut -f 1)

if [[ -n "$DEBUG" ]]; then
  echo "latest_sha: ${latest_sha}" >&2
fi

req_commit_sha=${latest_sha}

short_sha=${req_commit_sha:0:10}
if [[ -n "$DEBUG" ]]; then
  echo "short_sha: ${short_sha}" >&2
fi

if [[ "${short_sha}" == "" ]]; then
  echo "Error: could not get SHA of latest commit " >&2
  exit 2
fi


# Fail or reformat directory name if dir already exists

echo "Checking for existing directory from latest commit..." >&2

target_dir=.mf_${short_sha}

if [[ -d "$target_dir" || -d "$target_dir.*" ]]; then
  if [[ "${force_update}" == "n" ]]; then
    if [[ "$idempotent" == "y" ]]; then
      exit
    else
      echo "Module files are already up-to-date: use \"-f\" to force the creation of a new copy and relinking." >&2
      exit 2
    fi
  else
    echo "Forcing update..." >&2
    suffix_number=0
   
    new_target_dir=${target_dir} 
    while [[ -a "${new_target_dir}" ]]; do
      new_target_dir=${target_dir}.${suffix_number}
      suffix_number=$(( suffix_number + 1 ))
    done
    target_dir=${new_target_dir}
  fi
fi


git clone --depth=1 -b "${branch}" https://github.com/UCL-RITS/rcps-modulefiles.git "${target_dir}"
echo "${req_commit_sha}" >"${target_dir}/.commit_sha"

most_recent_log="$(cd "${moduledirs_path}/${target_dir}" && git log -n 1 --no-decorate --oneline)"

# We remove the repo information to dissuade people performing git operations on the prod copy
echo "Removing superfluous repo information..." >&2
rm -Rf "${target_dir:-/if_you_see_this_it_means_target_dir_variable_was_empty_somehow}/.git"

echo "Linking..." >&2
ln -Tfs "${target_dir}" modulefiles

if [[ "$remove_old_mfs" == "true" ]]; then
    echo "Removing module dirs older than 7 days..." >&2
    rm_count=0
    skip_count=0
    for dir in $(find -L \
                    "${moduledirs_path:?error: no module dirs path set}" \
                    -maxdepth 1 \
                    -type d \
                    -name ".mf_*" \
                    -ctime +7 \
                    | grep -v "${target_dir}" )
    do
        if [[ ! -a "$dir/.keep" ]]; then
            'rm' -rf "${dir}"
            rm_count=$(( rm_count + 1 ))
        else
            skip_count=$(( skip_count + 1 ))
        fi
    done
    echo "Removed $rm_count dirs, skipped $skip_count dirs marked to keep." >&2
fi

echo "--Done--" >&2

num_old_module_dirs="$(find -L "$moduledirs_path" -maxdepth 1 -type d -name ".mf_*" | wc -l)"
echo "Module dirs in ${moduledirs_path}: ${num_old_module_dirs}" >&2
echo "Most recent log in active dir: $most_recent_log"