Cloud-Synced Folders Break App Builds — Excluding Build Artifacts From Sync to Fix It for Good

Dropbox: exclude each folder with an extended attribute

Dropbox has an extended attribute that marks a folder as "do not sync." On macOS you set com.dropbox.ignored on the target folder with the xattr command. The steps are as follows.

1. Delete existing conflicted copies to clean up the state
2. Set the com.dropbox.ignored attribute on the target folder
3. Confirm the attribute is set with xattr -p

# Exclude the folder from Dropbox sync (macOS)
# Setting the value to 1 keeps it locally but stops syncing it
xattr -w com.dropbox.ignored 1 ios/Pods
xattr -w com.dropbox.ignored 1 node_modules
 
# Confirm it is set (a returned 1 means excluded)
xattr -p com.dropbox.ignored node_modules
# => 1

A note of caution: even after exclusion the folder stays local. The build works as before; it just stops uploading to the cloud. If conflicted copies are already scattered around, delete them first, then set the attribute for a clean result.

# Wipe existing conflicted copies before setting the exclusion attribute
find . -name "*conflicted copy*" | while read f; do
  echo "removing: $f"
  rm -rf "$f"
done

iCloud Drive: exclude by naming and relocation

iCloud Drive has no dedicated attribute like Dropbox. Instead there are two realistic ways to handle it.

One uses the convention that iCloud does not sync files or folders ending in .nosync. But renaming a folder makes the build tool lose its reference, so it is hard to apply to an artifact directory itself.

The other is reliable: place the working directory outside iCloud. Keep source in a non-synced location like ~/Developer/, and copy only the deliverables into iCloud when needed. In this case I choose to re-clone the whole repository into ~/Developer/. Rather than trying to pull artifacts out, it causes fewer accidents to never create them inside the synced area in the first place.

Stopping recurrence: one script to run at project creation

Excluding by hand once means forgetting the next time you create a project. I keep one small script to run at the end of every new setup, so artifacts are excluded mechanically.

#!/usr/bin/env bash
# dropbox-ignore-build-artifacts.sh
# Run at the project root to exclude regenerable directories from Dropbox sync.
set -euo pipefail
 
# Exclusion targets (list only what can be regenerated)
TARGETS=(
  "node_modules"
  "ios/Pods"
  "ios/build"
  "android/build"
  "android/.gradle"
  ".gradle"
  ".expo"
  ".expo-shared"
)
 
for dir in "${TARGETS[@]}"; do
  if [ -d "$dir" ]; then
    xattr -w com.dropbox.ignored 1 "$dir"
    echo "ignored: $dir"
  else
    # For ones not yet generated, pre-create an empty dir and set the attribute
    mkdir -p "$dir"
    xattr -w com.dropbox.ignored 1 "$dir"
    echo "pre-created & ignored: $dir"
  fi
done
 
echo "done. excluded folders stay local but will not sync."

Pre-creating an empty directory and setting the attribute is the small trick. If you set the attribute while node_modules does not yet exist, whatever the later npm install expands is excluded from the start. Locking in the exclusion before the artifacts are born is what let me create zero conflicted copies.

Confirming it works

Once the attributes are set, leave it a while and observe. I ran development and builds as usual for about three days and confirmed that not a single conflicted copy appeared.

# Periodically count whether conflicted copies are increasing
find . -name "*conflicted copy*" | wc -l
# => success if it stays at 0

If the number stays pinned at 0, the tug-of-war between sync and build is over. It is not a flashy result like a dashboard, but the single most demotivating accident — a red build first thing in the morning — was gone.

Wrapping up

Start by running find . -name "*conflicted copy*" once on the project you have open to see whether conflicted copies are mixed into node_modules. If even one shows up, that is the breeding ground for your intermittent build failures.

As an indie developer, all the effort of maintaining your own dev environment comes back to you. I myself repeated "clean and rebuild" many times without grasping the cause. Excluding artifacts from sync is an unglamorous move, but once decided it keeps working quietly. Thank you for reading.