@clsinit
class LinuxNode(ResourceManager):
+ """
+ .. class:: Class Args :
+
+ :param ec: The Experiment controller
+ :type ec: ExperimentController
+ :param guid: guid of the RM
+ :type guid: int
+
+ .. note::
+
+ There are different ways in which commands can be executed using the
+ LinuxNode interface (i.e. 'execute' - blocking and non blocking, 'run',
+ 'run_and_wait').
+
+ Brief explanation:
+
+ * 'execute' (blocking mode) :
+
+ HOW IT WORKS: 'execute', forks a process and run the
+ command, synchronously, attached to the terminal, in
+ foreground.
+ The execute method will block until the command returns
+ the result on 'out', 'err' (so until it finishes executing).
+
+ USAGE: short-lived commands that must be executed attached
+ to a terminal and in foreground, for which it IS necessary
+ to block until the command has finished (e.g. if you want
+ to run 'ls' or 'cat').
+
+ * 'execute' (NON blocking mode - blocking = False) :
+
+ HOW IT WORKS: Same as before, except that execute method
+ will return immediately (even if command still running).
+
+ USAGE: long-lived commands that must be executed attached
+ to a terminal and in foreground, but for which it is not
+ necessary to block until the command has finished. (e.g.
+ start an application using X11 forwarding)
+
+ * 'run' :
+
+ HOW IT WORKS: Connects to the host ( using SSH if remote)
+ and launches the command in background, detached from any
+ terminal (daemonized), and returns. The command continues to
+ run remotely, but since it is detached from the terminal,
+ its pipes (stdin, stdout, stderr) can't be redirected to the
+ console (as normal non detached processes would), and so they
+ are explicitly redirected to files. The pidfile is created as
+ part of the process of launching the command. The pidfile
+ holds the pid and ppid of the process forked in background,
+ so later on it is possible to check whether the command is still
+ running.
+
+ USAGE: long-lived commands that can run detached in background,
+ for which it is NOT necessary to block (wait) until the command
+ has finished. (e.g. start an application that is not using X11
+ forwarding. It can run detached and remotely in background)
+
+ * 'run_and_wait' :
+
+ HOW IT WORKS: Similar to 'run' except that it 'blocks' until
+ the command has finished execution. It also checks whether
+ errors occurred during runtime by reading the exitcode file,
+ which contains the exit code of the command that was run
+ (checking stderr only is not always reliable since many
+ commands throw debugging info to stderr and the only way to
+ automatically know whether an error really happened is to
+ check the process exit code).
+
+ Another difference with respect to 'run', is that instead
+ of directly executing the command as a bash command line,
+ it uploads the command to a bash script and runs the script.
+ This allows to use the bash script to debug errors, since
+ it remains at the remote host and can be run manually to
+ reproduce the error.
+
+ USAGE: medium-lived commands that can run detached in
+ background, for which it IS necessary to block (wait) until
+ the command has finished. (e.g. Package installation,
+ source compilation, file download, etc)
+
+ """
_rtype = "LinuxNode"
@classmethod
if not self.localhost:
# Build destination as <user>@<server>:<path>
dst = "%s@%s:%s" % (self.get("username"), self.get("hostname"), dst)
-
result = self.copy(src, dst)
# clean up temp file
tty = tty)
# check no errors occurred
- if proc.poll() and err:
+ if proc.poll():
msg = " Failed to run command '%s' " % command
self.error(msg, out, err)
if raise_on_error:
# wait until command finishes to execute
self.wait_run(pid, ppid)
- (out, err), proc = self.check_errors(home, ecodefile, stderr)
+ (out, err), proc = self.check_errors(home,
+ ecodefile = ecodefile,
+ stdout = stdout,
+ stderr= stderr)
# Out is what was written in the stderr file
- if out or err:
+ if err:
msg = " Failed to run command '%s' " % command
self.error(msg, out, err)
""" Saves the command as a bash script file in the remote host, and
forces to save the exit code of the command execution to the ecodefile
"""
-
- # Prepare command to be executed as a bash script file
- # Make sure command ends in ';' so the curly brackets syntax is correct
- if not command.strip()[-1] == ';':
- command += " ; "
+ if not (command.strip().endswith(";") or command.strip().endswith("&")):
+ command += ";"
+
# The exit code of the command will be stored in ecodefile
- command = " { { %(command)s } ; echo $? > %(ecodefile)s ; } " % {
+ command = " { %(command)s } ; echo $? > %(ecodefile)s ;" % {
'command': command,
'ecodefile': ecodefile,
}
# Export environment
- environ = "\n".join(map(lambda e: "export %s" % e, env.split(" "))) \
- if env else ""
+ environ = self.format_environment(env)
# Add environ to command
command = environ + command
dst = os.path.join(home, shfile)
return self.upload(command, dst, text = True)
+ def format_environment(self, env, inline = False):
+ """Format environmental variables for command to be executed either
+ as an inline command
+ (i.e. export PYTHONPATH=src/..; export LALAL= ..;python script.py) or
+ as a bash script (i.e. export PYTHONPATH=src/.. \n export LALA=.. \n)
+ """
+ if not env: return ""
+ env = env.strip()
+
+ sep = ";" if inline else "\n"
+ return sep.join(map(lambda e: " export %s" % e, env.split(" "))) + sep
+
def check_errors(self, home,
ecodefile = "exitcode",
+ stdout = "stdout",
stderr = "stderr"):
"""
Checks whether errors occurred while running a command.
It first checks the exit code for the command, and only if the
exit code is an error one it returns the error output.
+
"""
- out = err = ""
proc = None
+ err = ""
+ # retrive standard output from the file
+ (out, oerr), oproc = self.check_output(home, stdout)
- # get Exit code
+ # get exit code saved in the 'exitcode' file
ecode = self.exitcode(home, ecodefile)
if ecode in [ ExitCode.CORRUPTFILE, ExitCode.ERROR ]:
elif ecode > 0 or ecode == ExitCode.FILENOTFOUND:
# The process returned an error code or didn't exist.
# Check standard error.
- (out, err), proc = self.check_output(home, stderr)
-
- # If the stderr file was not found, assume nothing happened.
- # We just ignore the error.
+ (err, eerr), proc = self.check_output(home, stderr)
+
+ # If the stderr file was not found, assume nothing bad happened,
+ # and just ignore the error.
# (cat returns 1 for error "No such file or directory")
if ecode == ExitCode.FILENOTFOUND and proc.poll() == 1:
- out = err = ""
-
+ err = ""
+
return (out, err), proc
def wait_pid(self, home, pidfile = "pidfile", raise_on_error = False):
git://git.onelab.eu / nepi.git / blobdiff