On Tue, Mar 18, 2025 at 05:36:03PM +0100, Peter Krempa wrote:
> From: Peter Krempa <pkre...@redhat.com>
>
> As no argument parsing is employed the script is hard to use and when
> running without arguments it blurbs:
>
> $ ./scripts/render_block_graph.py
> Traceback (most recent call last):
> File "/home/pipo/git/qemu.git/./scripts/render_block_graph.py", line 135,
> in <module>
> obj = sys.argv[1]
> ~~~~~~~~^^^
> IndexError: list index out of range
>
> instead of an actionable error. The user then usually needs to read the
> script to understand arguments.
>
> Implement proper argument parsing via 'argparse'. The following
> arguments will be supported:
>
> $ ./scripts/render_block_graph.py --help
> usage: render_block_graph.py [-h] [--socket SOCKET] [--vm VM] [--uri URI]
> [--output OUTPUT]
>
> Tool that renders the qemu block graph into a image.
>
> options:
> -h, --help show this help message and exit
> --socket SOCKET direct mode - path to qemu monitor socket
> --vm VM libvirt mode - name of libvirt VM
> --uri URI libvirt URI to connect to
> --output OUTPUT path to output image; .png suffix will be added; in
> libvirt mode default is the name of the VM
>
> Usage then requires one of '--vm' or '--socket'. In libvirt mode the
> output file is by default populated from the VM name and the '--uri'
> parameter allows overriding the libvirt connection uri.
>
> Signed-off-by: Peter Krempa <pkre...@redhat.com>
> ---
> scripts/render_block_graph.py | 53 ++++++++++++++++++++++++++++-------
> 1 file changed, 43 insertions(+), 10 deletions(-)
>
> diff --git a/scripts/render_block_graph.py b/scripts/render_block_graph.py
> index 14b2d02ec2..7a6738410c 100755
> --- a/scripts/render_block_graph.py
> +++ b/scripts/render_block_graph.py
> @@ -23,6 +23,7 @@
> import subprocess
> import json
> from graphviz import Digraph
> +import argparse
>
> sys.path.append(os.path.join(os.path.dirname(__file__), '..', 'python'))
> from qemu.qmp import QMPError
> @@ -91,13 +92,19 @@ def render_block_graph(qmp, filename, format='png'):
>
>
> class LibvirtGuest():
> - def __init__(self, name):
> + def __init__(self, name, uri=None):
> self.name = name
> + self.uri = uri
>
> def cmd(self, cmd):
> # only supports qmp commands without parameters
> m = {'execute': cmd}
> - ar = ['virsh', 'qemu-monitor-command', self.name, json.dumps(m)]
> + ar = ['virsh']
> +
> + if self.uri:
> + ar += ['-c', self.uri]
> +
> + ar += ['qemu-monitor-command', self.name, json.dumps(m)]
>
> reply = json.loads(subprocess.check_output(ar))
>
> @@ -108,15 +115,41 @@ def cmd(self, cmd):
>
>
> if __name__ == '__main__':
> - obj = sys.argv[1]
> - out = sys.argv[2]
> + parser = argparse.ArgumentParser(
> + description='Tool that renders the qemu block graph into a
> image.')
> +
> + parser.add_argument('--socket',
> + help='direct mode - path to qemu monitor socket')
> +
> + parser.add_argument('--vm', help='libvirt mode - name of libvirt VM')
> + parser.add_argument('--uri', help='libvirt URI to connect to')
> +
> + parser.add_argument('--output',
> + help='path to output image (.png suffix added);'
> + 'in libvirt mode default is the name of the VM')
> +
> + args = parser.parse_args()
>
> - if os.path.exists(obj):
> - # assume unix socket
> - qmp = QEMUMonitorProtocol(obj)
> + if (args.socket and args.vm) or (not args.socket and not args.vm):
> + print("One of --socket or --vm is required.", file=sys.stderr)
> + parser.print_help()
> + sys.exit(1)
It's possible to do with argparse as well:
modegroup = parser.add_mutually_exclusive_group(required=True)
modegroup.add_argument('--socket',
help='direct mode - path to qemu monitor socket')
modegroup.add_argument('--vm', help='libvirt mode - name of libvirt VM')
The only difference is that it will print usage `parser.print_usage()`.
> +
> + if args.socket:
> + qmp = QEMUMonitorProtocol(args.socket)
> qmp.connect()
> - else:
> - # assume libvirt guest name
> - qmp = LibvirtGuest(obj)
> +
> + if args.vm:
> + qmp = LibvirtGuest(args.vm, args.uri)
> +
> + if args.output:
> + out = args.output
> + else:
> + out = args.vm
> +
> + if not out:
This needs to use args.output otherwise python will complain that it
doesn't know `out` variable.
> + print("--output required", file=sys.stderr)
> + parser.print_help()
Probably use `parser.print_usage()` if you decide to use the
add_mutually_exclusive_group().
Pavel
> + sys.exit(1)
>
> render_block_graph(qmp, out)
> --
> 2.48.1
>
>
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