Run background iperf3 tests with --json-stream option always

Either iperf3 is run from a pod (we recommend to use a certain centos10
pod) or from the supported Fedora 41 Advanced VM instances, iperf3
supports the --json-stream option on those environments (iperf version
greater or equal to 3.17).
This option can be used with --logfile (the output is written for every
iperf3 interval on a file) or without it (the output is written to
stdout).
This option should not be used when iperf3 is run from the test
machine/container: undercloud, devstack, tobiko pod (in case of podified
envs).

Change-Id: I0491dbff33619ca3096a9eeac70ae4a46c68b62d

tobiko/podified/_openshift.py

@@ -502,7 +502,7 @@ def start_iperf3(
     parameters = iperf3.iperf3_client_parameters(
         address=address, bitrate=bitrate,
         download=download, port=port, protocol=protocol,
-        timeout=0, logfile=iperf3.JSON_STREAM)
+        timeout=0, json_stream=True)
 
     cmd_args = iperf3.get_iperf3_client_command(
             parameters).as_list()[1:]

tobiko/shell/iperf3/__init__.py

@@ -20,7 +20,6 @@ from tobiko.shell.iperf3 import _execute
 from tobiko.shell.iperf3 import _interface
 from tobiko.shell.iperf3 import _parameters
 
-JSON_STREAM = _interface.JSON_STREAM
 
 assert_has_bandwith_limits = _assert.assert_has_bandwith_limits
 execute_iperf3_client_in_background = \

tobiko/shell/iperf3/_execute.py

@@ -89,10 +89,19 @@ def execute_iperf3_client(address: typing.Union[str, netaddr.IPAddress],
         params_timeout = 0
     elif timeout is not None:
         params_timeout = int(timeout - 0.5)
+
+    # json_stream option should be set when:
+    # - tests are run_in_background
+    # - tests are executed from a VM instance
+    # This way we avoid using that option from the test machine (undercloud,
+    # test pod, devstack, ...) where it is not supported
+    # iperf3 support this option from version 3.17
+    json_stream = run_in_background and (ssh_client is not None)
+
     parameters = _parameters.iperf3_client_parameters(
         address=address, bitrate=bitrate,
         download=download, port=port, protocol=protocol,
-        timeout=params_timeout, logfile=logfile)
+        timeout=params_timeout, json_stream=json_stream, logfile=logfile)
     command = _interface.get_iperf3_client_command(parameters)
 
     # output is a dictionary

tobiko/shell/iperf3/_interface.py

@@ -23,8 +23,6 @@ from tobiko.shell import sh
 
 LOG = log.getLogger(__name__)
 
-JSON_STREAM = "json-stream"
-
 
 def get_iperf3_client_command(parameters: _parameters.Iperf3ClientParameters):
     interface = Iperf3Interface()
@@ -68,6 +66,8 @@ class Iperf3Interface:
             options += self.get_download_option(parameters.download)
         if parameters.protocol is not None:
             options += self.get_protocol_option(parameters.protocol)
+        if parameters.json_stream is not None:
+            options += self.get_json_stream_option(parameters.json_stream)
         if parameters.logfile is not None:
             options += self.get_logfile_option(parameters.logfile)
         return options
@@ -124,7 +124,15 @@ class Iperf3Interface:
         return ['-p', port]
 
     @staticmethod
-    def get_logfile_option(logfile):
-        if logfile == JSON_STREAM:
+    def get_json_stream_option(json_stream: bool):
+        # NOTE: when iperf3 is run with --json-stream, new json
+        # entries are written for every interval
+        # This option is supported from iperf3 version 3.17:
+        if json_stream:
             return ['--json-stream']
+        else:
+            return []
+
+    @staticmethod
+    def get_logfile_option(logfile):
         return ['--logfile', logfile]

tobiko/shell/iperf3/_parameters.py

@@ -29,6 +29,7 @@ class Iperf3ClientParameters(typing.NamedTuple):
     port: typing.Optional[int] = None
     protocol: typing.Optional[str] = None
     timeout: typing.Optional[int] = None
+    json_stream: typing.Optional[bool] = None
     logfile: typing.Optional[str] = None
 
 
@@ -44,6 +45,7 @@ def iperf3_client_parameters(
         port: int = None,
         protocol: str = None,
         timeout: int = None,
+        json_stream: bool = None,
         logfile: str = None):
     """Get iperf3 client parameters
     mode allowed values: client or server
@@ -68,6 +70,7 @@ def iperf3_client_parameters(
                                   port=port,
                                   protocol=protocol,
                                   timeout=timeout,
+                                  json_stream=json_stream,
                                   logfile=logfile)