Unable to make a new command (like `tree`) available in configure hook

snapcraft
1

I want to use tree -p on SNAP_COMMON, SNAP_DATA, and SNAP to troubleshoot what is visible / readable / writable when running my configure hook, but what I’ve tried so far did not work:

  • First try
    override-build: | 
 apt-get install -y tree
 ...
  • Second try
    stage-packages:
  - tree

But my configure script invariably fails with

===> [  SNAP_DATA contents ]

+ tree -p /var/snap/btcd/x14
/snap/btcd/x14/meta/hooks/configure: line 23: tree: command not found

Suggestions?

2

apt-install tree can be achieved through use of build-packages, but this solution will not work as it installs packages onto the host to support the build of the snap and do not necessarily become part of the snap.

stage-packages should work, but hooks run with a different environment that that of regular entries under apps. As such, there is no default path, so I would change your tree command to something like $SNAP/usr/bin/tree (or $SNAP/bin/tree depending on where tree lives within the snap).

3

@sergiusens thx, that works but I had to create a helper function to get more visibility into what’s where.

Adding it here in case someone else needs to ‘run that script, wherever that script happens to be’

function banner() {
  echo -e "\n===> [" "$@" "]\n" 1>&2
}
function whereis() {
  local name="$1" && shift 1
  local cmd_path=""

  local cmd_from_find=$(find "${SNAP}" -type f -executable -name "${name}")
  if [[ -n "${cmd_from_find}" ]]; then
    cmd_path="${cmd_from_find}"
  fi

  local cmd_from_path=$(command -v "${name}")
  if [[ -n "${cmd_from_path}" ]]; then
    cmd_path="${cmd_from_path}"
  fi

  banner "whereis '${name}'"
  echo "find says: ${cmd_from_find:-not found}" 1>&2
  echo "PATH says: ${cmd_from_path:-not found}" 1>&2
  echo "using: ${cmd_path}" 1>&2
  echo "permissions: $(ls -la "${cmd_path}")" 1>&2
  echo "${cmd_path}"
}
...

Then I can actually do what it is I wanted to do, which is, again, to get more visibility into what’s going on (you can see the theme here)

function dump_manifest() {
  local _tree=$(whereis "tree")
  for dir in SNAP_COMMON SNAP_DATA; do
    banner "${dir}"
    eval "${_tree}" -puglFCh --du --inodes "\${${dir}}" | eval tee "${hook_dir}/${dir}.manifest"
  done
}
trap dump_manifest EXIT
1 Like