replace subprocess call with os.execvpe if run as separate process (#78)

Author: dfangl

README.md

@@ -92,7 +92,7 @@ pip install https://github.com/boto/botocore/archive/v2.zip https://github.com/a
 
 ## Change Log
 
-* v0.21: Use placeholder credentials and region only if Boto cannot not find them
+* v0.21: Use placeholder credentials and region only if Boto cannot not find them, fix output streaming for logs tail call
 * v0.20: Small fixes for Python 2.x backward compatibility
 * v0.19: Patch botocore to skip adding `data-` host prefixes to endpoint URLs
 * v0.18: Pass `SYSTEMROOT` env variable to fix "_Py_HashRandomization_Init" error on Windows

bin/awslocal

@@ -31,7 +31,7 @@ if os.path.isdir(os.path.join(PARENT_FOLDER, '.venv')):
     sys.path.insert(0, PARENT_FOLDER)
 
 # names of additional environment variables to pass to subprocess
-ENV_VARS_TO_PASS = ['PATH', 'PYTHONPATH', 'SYSTEMROOT', 'HOME']
+ENV_VARS_TO_PASS = ['PATH', 'PYTHONPATH', 'SYSTEMROOT', 'HOME', 'TERM', 'PAGER']
 
 from localstack_client import config  # noqa: E402
 
@@ -54,24 +54,13 @@ def usage():
     print(__doc__.strip())
 
 
-def run(cmd, env={}):
-
-    def output_reader(pipe, out):
-        out_binary = os.fdopen(out.fileno(), 'wb')
-        with pipe:
-            for line in iter(pipe.readline, b''):
-                out_binary.write(line)
-                out_binary.flush()
-
-    process = subprocess.Popen(
-        cmd, env=env,
-        stderr=subprocess.PIPE, stdout=subprocess.PIPE, stdin=subprocess.PIPE)
-
-    Thread(target=output_reader, args=[process.stdout, sys.stdout]).start()
-    Thread(target=output_reader, args=[process.stderr, sys.stderr]).start()
-
-    process.wait()
-    sys.exit(process.returncode)
+def run(cmd, env=None):
+    """
+    Replaces this process with the AWS CLI process, with the given command and environment
+    """
+    if not env:
+        env = {}
+    os.execvpe(cmd[0], cmd, env)
 
 
 def awscli_is_v1():