Merge lp:~strikov-deactivatedaccount/curtin/multipath-2 into lp:~curtin-dev/curtin/trunk

[Scott Moser]

[Scott Moser (smoser)]

So, some thoughts here.
a.) we're using 'strip' on the output of /lib/udev/scsi_id which is less than ideal. that was done to drop the trailing '\n'. the result is that we'd recognize ' DISK 1 ' and 'DISK 1' as the same device and take the "enable_multipath" path. Both not very likely and not very big deal, but odd. I guess probably we should:
  if len(scsi_id) and scsi_id[-1] == '\n':
     scsi_id = scsi_id[0:-1]

  not a big deal, but worth fixing

b.) the other hting i'm concerned about is if the image / environment that we're installing in has multipath-tools installed, it may see that /dev/sda (and /dev/sde) is used by /dev/dm-0. and then choose not to install to it, or not realize that and fail to install.

in that scenario, i think the first install possibly works, while subsequent ones fail.
we may need a way to un-setup the dm devices so we can install to the "raw" ones.

[Scott Moser (smoser)]

oh yeah, and 'c'
i'm not sure if this works or not in python3.
a test would be nice to make sure.

[lp:~strikov-deactivatedaccount/curtin/multipath-2]

211. By Oleg Strikov on 2015-06-04

block: multipath: Do not strip scsi_id, just remove trailing newlines.

Two devices may have similar scsi_ids with the only difference in the
exact amount of spaces in the beginning or in the end. By using strip()
we treat these devices as multipath ones. That's wrong because multipath
assumes identical scsi_ids of the devices.

212. By Oleg Strikov on 2015-06-05

block_meta: Stop all multipath devices before installing the system.

Multipath devices might be automatically assembled if multipath-tools
package is available in the installation environment. We need to stop
all multipath devices to exclusively use one of paths as a target disk.

213. By Oleg Strikov on 2015-06-05

block, block_meta: Stylistic changes.

214. By Oleg Strikov on 2015-06-05

curthooks: multipath: Few changes to the way multipath.conf is generated.

a) Don't overwrite multipath.conf provided by the installation image.
b) Add header to the file which state that file was generated by curtin.

=== modified file 'curtin/block/__init__.py'
--- curtin/block/__init__.py	2015-05-13 13:30:56 +0000
+++ curtin/block/__init__.py	2015-06-05 16:58:55 +0000
@@ -22,6 +22,7 @@
 import tempfile
 
 from curtin import util
+from curtin.log import LOG
 
 
 def get_dev_name_entry(devname):
@@ -179,6 +180,58 @@
     return ret
 
 
+def stop_all_unused_multipath_devices():
+    """
+    Stop all unused multipath devices.
+    """
+    multipath = util.which('multipath')
+
+    # Command multipath is not available only when multipath-tools package
+    # is not installed. Nothing needs to be done in this case because system
+    # doesn't create multipath devices without this package installed and we
+    # have nothing to stop.
+    if not multipath:
+        return
+
+    # Command multipath -F flushes all unused multipath device maps
+    cmd = [multipath, '-F']
+    try:
+        util.subp(cmd)
+    except util.ProcessExecutionError as e:
+        LOG.warn("Failed to stop multipath devices: %s", e)
+
+
+def detect_multipath():
+    """
+    Figure out if target machine has any multipath devices.
+    """
+    # Multipath-tools are not available in the ephemeral image.
+    # This workaround detects multipath by looking for multiple
+    # devices with the same scsi id (serial number).
+    disk_ids = []
+    bdinfo = _lsblock(['--nodeps'])
+    for devname, data in bdinfo.items():
+        # Command scsi_id returns error while running against cdrom devices.
+        # To prevent getting unexpected errors for some other types of devices
+        # we ignore everything except hard disks.
+        if data['TYPE'] != 'disk':
+            continue
+
+        cmd = ['/lib/udev/scsi_id', '--replace-whitespace',
+               '--whitelisted', '--device=%s' % data['device_path']]
+        try:
+            (out, err) = util.subp(cmd, capture=True)
+            scsi_id = out.rstrip('\n')
+            # ignore empty ids because they are meaningless
+            if scsi_id:
+                disk_ids.append(scsi_id)
+        except util.ProcessExecutionError as e:
+            LOG.warn("Failed to get disk id: %s", e)
+
+    duplicates_found = (len(disk_ids) != len(set(disk_ids)))
+    return duplicates_found
+
+
 def get_root_device(dev, fpath="curtin"):
     """
     Get root partition for specified device, based on presence of /curtin.

=== modified file 'curtin/commands/block_meta.py'
--- curtin/commands/block_meta.py	2015-05-07 03:58:10 +0000
+++ curtin/commands/block_meta.py	2015-06-05 16:58:55 +0000
@@ -146,6 +146,11 @@
     # Remove duplicates but maintain ordering.
     devices = list(OrderedDict.fromkeys(devices))
 
+    # Multipath devices might be automatically assembled if multipath-tools
+    # package is available in the installation environment. We need to stop
+    # all multipath devices to exclusively use one of paths as a target disk.
+    block.stop_all_unused_multipath_devices()
+
     if len(devices) == 0:
         devices = block.get_installable_blockdevs()
         LOG.warn("'%s' mode, no devices given. unused list: %s",

=== modified file 'curtin/commands/curthooks.py'
--- curtin/commands/curthooks.py	2015-03-11 17:03:33 +0000
+++ curtin/commands/curthooks.py	2015-06-05 16:58:55 +0000
@@ -419,6 +419,41 @@
                         maxsize=maxsize)
 
 
+def detect_and_handle_multipath(cfg, target):
+    DEFAULT_MULTIPATH_PACKAGES = ['multipath-tools-boot']
+    mpcfg = cfg.get('multipath', {})
+    mpmode = mpcfg.get('mode', 'auto')
+    mppkgs = mpcfg.get('packages', DEFAULT_MULTIPATH_PACKAGES)
+    if isinstance(mppkgs, str):
+        mppkgs = [mppkgs]
+
+    if mpmode == 'disabled':
+        return
+
+    if mpmode == 'auto' and not block.detect_multipath():
+        return
+
+    util.install_packages(mppkgs, target=target)
+
+    multipath_cfg_path = os.path.sep.join([target, '/etc/multipath.conf'])
+    # We don't want to overwrite multipath.conf file provided by the image.
+    if os.path.isfile(multipath_cfg_path):
+        return
+
+    # Without user_friendly_names option enabled system fails to boot
+    # if any of the disks has spaces in its name. Package multipath-tools
+    # has bug opened for this issue (LP: 1432062) but it was not fixed yet.
+    multipath_cfg_content = '\n'.join(
+        ['# This file was generated by curtin while installing the system.',
+         'defaults {',
+         '	user_friendly_names yes',
+         '}',
+         ''])
+    util.write_file(multipath_cfg_path, content=multipath_cfg_content)
+    # Initrams needs to be regenerated to include updated multipath.cfg
+    update_initramfs(target)
+
+
 def curthooks(args):
     state = util.load_command_environment()
 
@@ -452,6 +487,8 @@
     copy_interfaces(state.get('interfaces'), target)
     copy_fstab(state.get('fstab'), target)
 
+    detect_and_handle_multipath(cfg, target)
+
     # As a rule, ARMv7 systems don't use grub. This may change some
     # day, but for now, assume no. They do require the initramfs
     # to be updated, and this also triggers boot loader setup via