disks: add per-host override using --disks=host:[device[,device]*]

Fills the role of --sr_disk, except that:
- it is per-host
- the default is "all disks", use empty device list to forbid all disks
  on a host

Signed-off-by: Yann Dirson <[email protected]>

Author: ydirson

conftest.py

@@ -8,12 +8,12 @@
 import tempfile
 
 from packaging import version
-from typing import Dict, Generator
+from typing import Dict, Generator, Iterable
 
 import lib.config as global_config
 
 from lib import pxe
-from lib.common import DiskDevName
+from lib.common import DiskDevName, HostAddress
 from lib.common import callable_marker, shortened_nodeid, prefix_object_name
 from lib.common import wait_for, vm_image, is_uuid
 from lib.common import setup_formatted_and_mounted_disk, teardown_formatted_and_mounted_disk
@@ -75,6 +75,14 @@ def pytest_addoption(parser):
         default=20,
         help="Max lines to output in a ssh log (0 if no limit)"
     )
+    parser.addoption(
+        "--disks",
+        action="append",
+        default=[],
+        help="HOST:DISKS to authorize for use by tests. "
+             "DISKS is a possibly-empty comma-separated list. "
+             "No mention of a given host authorizes use of all its disks."
+    )
     parser.addoption(
         "--sr-disk",
         action="append",
@@ -219,6 +227,14 @@ def cleanup_hosts():
 
     cleanup_hosts()
 
+@pytest.fixture(scope='session')
+def pools_hosts_by_name_or_ip(hosts: list[Host]) -> Generator[dict[HostAddress, Host]]:
+    """All hosts of all pools, each indexed by their hostname_or_ip."""
+    yield {host.hostname_or_ip: host
+           for pool_master in hosts
+           for host in pool_master.pool.hosts
+           }
+
 @pytest.fixture(scope='session')
 def registered_xo_cli():
     # The fixture is not responsible for establishing the connection.
@@ -331,10 +347,32 @@ def local_sr_on_hostB1(hostB1):
     yield sr
 
 @pytest.fixture(scope='session')
-def disks(hosts: list[Host]) -> Generator[dict[Host, list[DiskDevName]], None, None]:
-    ret = {host: host.disks()
-           for pool_master in hosts
-           for host in pool_master.pool.hosts
+def disks(pytestconfig, pools_hosts_by_name_or_ip: dict[Host, Host]
+          ) -> Generator[dict[Host, list[DiskDevName]]]:
+    def _parse_disk_option(option_text: str) -> tuple[HostAddress, list[DiskDevName]]:
+        parsed = option_text.split(sep=":", maxsplit=1)
+        assert len(parsed) == 2, f"--disks option {option_text!r} is not <host>:<disk>[,<disk>]*"
+        host_address, disks_string = parsed
+        devices = disks_string.split(',') if disks_string else []
+        return host_address, devices
+
+    cli_disks = dict(_parse_disk_option(option_text)
+                     for option_text in pytestconfig.getoption("disks"))
+
+    def _host_disks(host: Host, hosts_cli_disks: list[DiskDevName] | None) -> Iterable[DiskDevName]:
+        host_disks = host.disks()
+        # no disk specified = allow all
+        if hosts_cli_disks is None:
+            yield from host_disks
+            return
+        # check all disks in --disks=host:... exist
+        for cli_disk in hosts_cli_disks:
+            assert cli_disk in host_disks, \
+                f"no {cli_disk!r} disk on host {host.hostname_or_ip}, has {','.join(host_disks)}"
+            yield cli_disk
+
+    ret = {host: list(_host_disks(host, cli_disks.get(host.hostname_or_ip)))
+           for host in pools_hosts_by_name_or_ip.values()
            }
     logging.debug("disks collected: %s", {host.hostname_or_ip: value for host, value in ret.items()})
     yield ret