Bug: `sam build --use-container` fails with `LinkOutsideDestinationError` on 1.155.2 (npm symlink regression)

[tkd4444]

Description

After upgrading from aws-sam-cli 1.154.0 to aws-sam-cli 1.155.2, sam build --use-container started failing in AWS CodeBuild during artifact extraction from the build container with a LinkOutsideDestinationError caused by an npm symlink under node_modules/.bin.

Pinning back to aws-sam-cli==1.154.0 restores successful builds.

---

Steps to Reproduce

1. Use AWS CodeBuild on Amazon Linux 2 with Python 3.9
2. Install:

pip install awscli==1.44.52 aws-sam-cli==1.155.2

3. Have a SAM app with Node.js functions that include node_modules/.bin symlinks (e.g. is-docker)
4. Run:

sam build --use-container --template ${SAM_TEMPLATE} --debug

5. Build fails during artifact copy/extraction from the container

For comparison, the following succeeds with the same repository and build flow:

pip install awscli==1.44.49 aws-sam-cli==1.154.0

---

Expected Behavior

sam build --use-container completes successfully, as it did on 1.154.0.

---

Actual Behavior

Build aborts with:

Mounting /codebuild/output/src2979588853/src/hooks as /tmp/samcli/source:ro,delegated, inside runtime container
SAM_CONTAINER_ID: 17748ca2b368a46db0645723368639d985ed4cfc9de625d3fb60739b7a4942a5
package.json file not found. Continuing the build without dependencies.
Running NodejsNpmBuilder:CopySource

Error: './node_modules/.bin/is-docker' would link to '/codebuild/output/src2979588853/src/.aws-sam/build/is-docker/cli.js', which is outside the destination
Traceback:
  ...
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/lib/utils/tar.py", line 154, in extract_tarfile
    tar.extractall(path=unpack_dir, filter="data")
  ...
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/tarfile.py", line 805, in _get_filtered_attrs
    raise LinkOutsideDestinationError(member, target_path)

An unexpected error was encountered while executing "sam build".

Full traceback

Mounting /codebuild/output/src2979588853/src/hooks as /tmp/samcli/source:ro,delegated, inside runtime container
SAM_CONTAINER_ID: 17748ca2b368a46db0645723368639d985ed4cfc9de625d3fb60739b7a4942a5
package.json file not found. Continuing the build without dependencies.
 Running NodejsNpmBuilder:CopySource

Error: './node_modules/.bin/is-docker' would link to '/codebuild/output/src2979588853/src/.aws-sam/build/is-docker/cli.js', which is outside the destination
Traceback:
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/click/core.py", line 1082, in main
    rv = self.invoke(ctx)
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/click/core.py", line 1697, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/click/core.py", line 1443, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/click/core.py", line 788, in invoke
    return __callback(*args, **kwargs)
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/cli/cli_config_file.py", line 366, in wrapper
    return func(*args, **kwargs)
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/click/decorators.py", line 92, in new_func
    return ctx.invoke(f, obj, *args, **kwargs)
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/click/core.py", line 788, in invoke
    return __callback(*args, **kwargs)
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/lib/telemetry/metric.py", line 190, in wrapped
    raise exception
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/lib/telemetry/metric.py", line 155, in wrapped
    return_value = func(*args, **kwargs)
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/lib/utils/version_checker.py", line 43, in wrapped
    actual_result = func(*args, **kwargs)
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/cli/main.py", line 95, in wrapper
    return func(*args, **kwargs)
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/commands/build/command.py", line 172, in cli
    do_cli(
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/commands/build/command.py", line 264, in do_cli
    ctx.run()
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/commands/build/build_context.py", line 289, in run
    self._build_result = builder.build()
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/lib/build/app_builder.py", line 255, in build
    return ApplicationBuildResult(build_graph, build_strategy.build())
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/lib/build/build_strategy.py", line 415, in build
    return super().build()
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/lib/build/build_strategy.py", line 83, in build
    result.update(self._build_functions(self._build_graph))
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/lib/build/build_strategy.py", line 421, in _build_functions
    return self._run_builds_async(
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/lib/build/build_strategy.py", line 437, in _run_builds_async
    async_results = async_context.run_async()
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/lib/utils/async_utils.py", line 138, in run_async
    return run_given_tasks_async(self._async_tasks, event_loop)
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/lib/utils/async_utils.py", line 96, in run_given_tasks_async
    return event_loop.run_until_complete(_run_given_tasks_async(tasks, event_loop, executor))
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/asyncio/base_events.py", line 647, in run_until_complete
    return future.result()
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/lib/utils/async_utils.py", line 62, in _run_given_tasks_async
    raise result
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/concurrent/futures/thread.py", line 58, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/lib/build/build_strategy.py", line 448, in build_single_function_definition
    return self._delegate_build_strategy.build_single_function_definition(build_definition)
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/lib/build/build_strategy.py", line 594, in build_single_function_definition
    return self._cached_build_strategy.build_single_function_definition(build_definition)
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/lib/build/build_strategy.py", line 302, in build_single_function_definition
    build_result = self._delegate_build_strategy.build_single_function_definition(build_definition)
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/lib/build/build_strategy.py", line 167, in build_single_function_definition
    result = self._build_function(
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/lib/build/app_builder.py", line 765, in _build_function
    return self._build_function_on_container(
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/lib/build/app_builder.py", line 1037, in _build_function_on_container
    container.copy(result_dir_in_container, artifacts_dir)
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/local/docker/container.py", line 660, in copy
    extract_tarfile(file_obj=fp, unpack_dir=to_host_path, mount_symlinks=bool(self._mount_symlinks))
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/site-packages/samcli/lib/utils/tar.py", line 154, in extract_tarfile
    tar.extractall(path=unpack_dir, filter="data")
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/tarfile.py", line 2235, in extractall
    tarinfo = self._get_extract_tarinfo(member, filter_function, path)
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/tarfile.py", line 2289, in _get_extract_tarinfo
    self._handle_fatal_error(e)
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/tarfile.py", line 2287, in _get_extract_tarinfo
    tarinfo = filter_function(tarinfo, path)
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/tarfile.py", line 818, in data_filter
    new_attrs = _get_filtered_attrs(member, dest_path, True)
  File "/root/.pyenv/versions/3.9.17/lib/python3.9/tarfile.py", line 805, in _get_filtered_attrs
    raise LinkOutsideDestinationError(member, target_path)

An unexpected error was encountered while executing "sam build".

---

Root Cause (suspected)

The traceback points to samcli/lib/utils/tar.py calling tar.extractall(..., filter="data"). The "data" filter, introduced for security in Python's tarfile module, rejects symlinks whose resolved target falls outside the extraction destination. npm-generated symlinks in node_modules/.bin (e.g. is-docker -> ../is-docker/cli.js) are valid relative symlinks but appear to resolve outside the destination under this filter, causing the error.

This behavior was not present in 1.154.0, suggesting filter="data" was introduced or its handling changed in 1.155.2.

---

Environment

	Working	Failing
aws-sam-cli	1.154.0	1.155.2
awscli	1.44.49	1.44.52
boto3	1.42.26	1.42.59
botocore	1.42.59	1.42.62
OS	AWS CodeBuild / Amazon Linux 2	AWS CodeBuild / Amazon Linux 2
Python	3.9.17	3.9.17
Docker	20.10.24	20.10.24
Architecture	x86_64	x86_64

---

Workaround

Pin to aws-sam-cli==1.154.0:

pip install aws-sam-cli==1.154.0

[bnusunny]

Please add --mount-symlinks option to the sam build --use-container command. This is introduced here: #8721

[seshubaws]

Closing, please reopen if issue persists

[github-actions]

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[tkd4444]

Thanks @bnusunny. Adding --mount-symlinks option to the sam build --use-container command. resolved the issue and now all works as expected.