I'm using kubernetes, and I want to create tool which have the ability to do tcpdump on some interfaces.
The problem is that this tool is controlled from container container_A in POD_A which doesn't have tcpdump installed in it (and I can't change it at this point), while tcpdump ability can be executed from container_B in POD_B (different from POD_A)
So the solution I choosed is to create tcpdump on different container (container_B in POD_B) and then move the dump file from container_B to container_A.
For this I used something close to solution which is provided here:
Copy file from pod to host by using kubernetes python client
The problem now is that for using this solution I understand that the dump file should be closed on origin container before I copy it to the destination container. This can be causing a high disk usage on container_A which has a low disk space attached to it while container_B has a big disk space attached to it.
I will paste the code from the link here for reference
def stream_copy_from_pod(self, pod_name, name_space, source_path, destination_path):
"""
Copy file from pod to the host.
:param pod_name: String. Pod name
:param name_space: String. Namespace
:param source_path: String. Pod destination file path
:param destination_path: Host destination file path
:return: bool
"""
command_copy = ['tar', 'cf', '-', source_path]
with TemporaryFile() as tar_buffer:
exec_stream = stream(self.coreClient.connect_get_namespaced_pod_exec, pod_name, name_space,
command=command_copy, stderr=True, stdin=True, stdout=True, tty=False,
_preload_content=False)
# Copy file to stream
try:
reader = WSFileManager(exec_stream)
while True:
out, err, closed = reader.read_bytes()
if out:
tar_buffer.write(out)
elif err:
logger.debug("Error copying file {0}".format(err.decode("utf-8", "replace")))
if closed:
break
exec_stream.close()
tar_buffer.flush()
tar_buffer.seek(0)
with tarfile.open(fileobj=tar_buffer, mode='r:') as tar:
member = tar.getmember(source_path)
tar.makefile(member, destination_path)
return True
except Exception as e:
raise manage_kubernetes_exception(e)
My question is can I use somehow the exec_stream with addaptaion provided in the example (or another kubernetes-client python api) and tcpdump command om container_B to stream the tcpdump straight to some tarball file (or another type of file) on container_A?
My assumption is that I just need to open stream container_B and send command="tcpdump ..." in a way that it will be stream the tcpdump to stdout of this container and "fetch" + "handle" this stdout from the stream into file in container_A, but is there a better way to do it?
