Debugging

Debugging Copybara

Techniques for troubleshooting workflows.

Verbose Output

Increase logging verbosity:

java -jar copybara.jar migrate copy.bara.sky export -v
java -jar copybara.jar migrate copy.bara.sky export -vv  # More verbose

Dry Run

See what would happen without making changes:

java -jar copybara.jar migrate copy.bara.sky export --dry-run

Local Testing

Use folder destination to preview output:

java -jar copybara.jar migrate copy.bara.sky export \
  --folder-destination /tmp/output

Then inspect:

find /tmp/output -type f
diff -r /tmp/output expected/

Validate Configuration

Check config before running:

java -jar copybara.jar validate copy.bara.sky export

Test Transforms

Create a test workflow:

core.workflow(
    name = "test-transforms",
    origin = folder.origin(),
    destination = folder.destination(),
    authoring = authoring.overwrite("Test <test@example.com>"),
    transformations = [
        # Your transforms here
    ],
)

Run locally:

java -jar copybara.jar migrate copy.bara.sky test-transforms \
  --folder-origin /path/to/source \
  --folder-destination /tmp/output

Check State

Find last synced commit:

# In destination repo
git log --grep="GitOrigin-RevId" -1

# Shows:
# GitOrigin-RevId: abc123def456

Debug Globs

Test which files match:

# Temporarily use very specific include
origin_files = glob(["src/specific-file.txt"])

Then expand as needed.

Console Logging

In dynamic transforms:

def _my_transform(ctx):
    ctx.console.info("Processing files...")
    for f in ctx.run(glob(["**"])):
        ctx.console.info("Found: " + f)
    return ctx.success()

Save Output

Save console output to file:

java -jar copybara.jar migrate copy.bara.sky export \
  --console-file-path copybara.log 2>&1 | tee copybara.log

Common Debug Scenarios

Check what files are included

java -jar copybara.jar migrate copy.bara.sky export \
  --folder-destination /tmp/test
find /tmp/test -type f

Verify replacements

java -jar copybara.jar migrate copy.bara.sky export \
  --folder-destination /tmp/test
grep -r "old_text" /tmp/test  # Should not find
grep -r "new_text" /tmp/test  # Should find

Check commit message

java -jar copybara.jar migrate copy.bara.sky export \
  --folder-destination /tmp/test
cd /tmp/test
git log -1

Test regex patterns

Use a regex tester or:

# Python
import re
pattern = r"your_pattern"
text = "your text"
print(re.findall(pattern, text))

Workflow Info

Get information about a workflow:

java -jar copybara.jar info copy.bara.sky export