Description of problem:
When using crushtool to create a CRUSH map, it is not possible to create a complex CRUSH map, we have to edit the CRUSH map and modify it manually to do it.

Could be possible to be able to modify the CRUSH map using similar commands as the ceph osd crush { add-bucket, move or set } commands to automatically create their associated IDs and update the CRUSH map that would be generated by the crushtool --build.


Expected results:
Here is an example that would help : I'm trying to create a CRUSH map with 2 root buckets using different hosts with different number of OSDs in them.


crushtool --outfn testmap.bin --build --num_osds 60 host straw2 20 root straw2 0

Then, I would be using something similar to these commands on testmap.bin to create the new buckets

# ceph osd crush add-bucket root1 root => crushtool -i testmap.bin add-bucket root1 root
# ceph osd crush add-bucket host0-zone2 host => crushtool -i testmap.bin add-bucket host0-zone2 host
# ceph osd crush add-bucket host1-zone2 host => crushtool -i testmap.bin add-bucket host1-zone2 host
# ceph osd crush add-bucket host2-zone2 host => crushtool -i testmap.bin add-bucket host2-zone2 host

Then, something similar to this to move the buckets into their correct locations
# ceph osd crush move host0-zone2 root=root1 => crushtool -i testmap.bin move host0-zone2 root=root1
# ceph osd crush move host1-zone2 root=root1 => crushtool -i testmap.bin move host1-zone2 root=root1
# ceph osd crush move host2-zone2 root=root1 => crushtool -i testmap.bin move host2-zone2 root=root1

And, finally moving the OSDs into their correct new host similar to this :
# ceph osd crush set osd.18 <weight> root=root1 host=host0-zone2 => crushtool -i testmap.bin set osd.18 <weight> root=root1 host=host0-zone2
# ceph osd crush set osd.19 <weight> root=root1 host=host0-zone2 => crushtool -i testmap.bin set osd.19 <weight> root=root1 host=host0-zone2

# ceph osd crush set osd.38 <weight> root=root1 host=host1-zone2 => crushtool -i testmap.bin set osd.38 <weight> root=root1 host=host0-zone2
# ceph osd crush set osd.39 <weight> root=root1 host=host1-zone2 => crushtool -i testmap.bin set osd.39 <weight> root=root1 host=host0-zone2

# ceph osd crush set osd.58 <CRUSH Weight (take it from its former value)> root=root1 host=host2-zone2 => crushtool -i testmap.bin set osd.58 <weight> root=root1 host=host0-zone5
# ceph osd crush set osd.59 <CRUSH Weight (take it from its former value)> root=root1 host=host2-zone2 => crushtool -i testmap.bin set osd.59 <weight> root=root1 host=host0-zone2


Additional info:
Many Thanks,
Eric.