def _ssh(self, command, stdin=None):
"""Run a command via SSH.
Args:
command: string or list of the command to run
stdin: optional, values to be passed in
Returns:
tuple of stdout, stderr and the return code
"""
client = self._ssh_connect()
cmd = shell_pack(command)
fp_in, fp_out, fp_err = client.exec_command(cmd)
channel = fp_in.channel
if stdin is not None:
fp_in.write(stdin)
fp_in.close()
channel.shutdown_write()
out = fp_out.read()
err = fp_err.read()
return_code = channel.recv_exit_status()
out = '' if not out else out.rstrip().decode("utf-8")
err = '' if not err else err.rstrip().decode("utf-8")
return Result(out, err, return_code)
def test_happy_path(self, m_subp):
"""Command succeeds and returns valid YAML."""
image_id = "my:image_id"
content = {"my": "data"}
m_subp.return_value = Result(yaml.dump(content), "", 0)
ret = LXDVirtualMachine(tag="test")._lxc_image_info(image_id)
assert content == ret
expected_call = mock.call(["lxc", "image", "info", image_id], rcs=())
assert [expected_call] == m_subp.call_args_list
def _ssh(self, command, stdin=None):
"""Run a command via SSH.
Args:
command: string or list of the command to run
stdin: optional, values to be passed in
Returns:
tuple of stdout, stderr and the return code
"""
cmd = shell_pack(command)
for _ in range(10):
try:
client = self._ssh_connect()
fp_in, fp_out, fp_err = client.exec_command(cmd)
break
except (ConnectionResetError, NoValidConnectionsError) as e:
last_error = e
# On OCI instances, attempting to re-connect without a longer
# sleep leaves you locked out of ssh completely
time.sleep(5)
else:
raise last_error # noqa
channel = fp_in.channel
if stdin is not None:
fp_in.write(stdin)
fp_in.close()
channel.shutdown_write()
out = fp_out.read()
err = fp_err.read()
return_code = channel.recv_exit_status()
out = '' if not out else out.rstrip().decode("utf-8")
err = '' if not err else err.rstrip().decode("utf-8")
return Result(out, err, return_code)
def test_invalid_yaml_returns_empty_dict(self, m_subp):
"""Invalid YAML even with command success returns empty dict."""
m_subp.return_value = Result("{:a}", "", 0)
assert {} == LXDVirtualMachine(tag="test")._lxc_image_info("image_id")
def test_command_failure_returns_empty_dict(self, m_subp):
"""Command failure even with valid YAML returns empty dict."""
content = {"my": "data"}
m_subp.return_value = Result(yaml.dump(content), "", 1)
assert {} == LXDVirtualMachine(tag="test")._lxc_image_info("image_id")
def subp(args,
data=None,
env=None,
shell=False,
rcs=(0, ),
shortcircuit_stdin=True):
"""Subprocess wrapper.
Args:
args: command to run
data: data to pass
env: optional env to use
shell: optional shell to use
rcs: tuple of successful exit codes, default: (0)
shortcircuit_stdin: bind stdin to /dev/null if no data is given
Returns:
Tuple of out, err, return_code
"""
devnull_fp = None
if data is not None:
stdin = subprocess.PIPE
if not isinstance(data, bytes):
data = data.encode()
elif shortcircuit_stdin:
# using devnull assures any reads get null, rather
# than possibly waiting on input.
devnull_fp = open(os.devnull)
stdin = devnull_fp
else:
stdin = None
bytes_args = _convert_args(args)
try:
process = subprocess.Popen(bytes_args,
stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
stdin=stdin,
env=env,
shell=shell)
(out, err) = process.communicate(data)
finally:
if devnull_fp:
devnull_fp.close()
rc = process.returncode
out = '' if not out else out.rstrip().decode("utf-8")
err = '' if not err else err.rstrip().decode("utf-8")
if rcs and rc not in rcs:
if err:
errmsg = err
elif out:
errmsg = out
else:
errmsg = "command failed silently"
errmsg = "Failure (rc=%s): %s" % (rc, errmsg)
raise RuntimeError(errmsg)
return Result(out, err, rc)