OVN/OVS Code Split
This is a rough proof of concept for a separation of OVN from its parent project, OVS. If you are interested in using OVN or OVS, please visit the OpenvSwitch official github page at https://github.com/openvswitch/ovs.git
Please feel free to try this out. For the moment, specific issues with the build are good to note, but it's not worth filing a bug report since this entire tree will likely be thrown away and redone.
For now, the best feedback would be about the viability of the overall approach. What was done well? What can be improved. Below, I've compiled a list of issues that I know about.
Approach
This repo was created by taking a clone of the OVS repo from the official upstream repository and then pushing it into an empty new github project. This was done to preserve the history of OVN files.
Next, a clone of the OVS master branch was added as a git subtree. This is the ovs/ subdirectory in this repo.
Next, files and subdirectories that were clearly OVS-only were removed from the repo. This includes the following directories:
- datapath
- datapath-windows
- include
- lib
- ofproto
- ovsdb
- utilities
- vswitchd
- vtep
- windows
Next, the ovn/ subdirectory had its contents moved to the top level, and the ovn/ subdirectory was removed.
Next, the build was stabilized. This mostly included altering Makefiles so that the project would build successfully.
Next, the ovn tests were verified to work. This mostly involved altering expected paths for files so that the tests could succeed.
Finally, the ovs sandbox was verified to run properly. This again consisted of altering paths in the ovs-sandbox in order to get everything running successfully.
What all works in this repo
OVN can be built using the make command.
All tests that match the -k ovn keyword pass.
You can run the ovs-sandbox with OVN by running make sandbox SANDBOXFLAGS="--ovn"
Installation of OVN using make install has not been tested, nor have any
additional build options. The build has only been tested on a Linux system, so
there may be build issues on BSD, Windows, or other systems currently supported
by OVS/OVN.
Instructions for building
Clone the ovn repo:
git clone https://github.com/putnopvut/ovn.git
Run the bootsrap and configure scripts:
./boot.sh ./configure.sh
Touch the manpages.mk file (we'll discuss this later):
touch manpages.mk
Build ovn:
make
Alternately, you can run OVN in a sandbox:
make sandbox SANDBOXFLAGS="--ovn"
Further work
As has been stated, this is a rough proof of concept. While some of the work will likely be reflected in the final product, there are a lot of areas that need improvement. These are detailed further in the sections below
Obvious improvements
At this point, the OVS subtree is completely untouched. In actuality, all OVN- specific content from the OVS subtree will need to be removed. Similarly, there is still some content in the OVN tree that can be removed. For instance, a great deal of the tests/ directory can be pruned. Also, repeated files in the Documentation/ directory can be removed.
Because repeated tests have not been removed, it results in some unexpected behaviors. If you attempt to run a test, then it will run the test first from within the ovs/tests/ directory, and then in the tests/ directory. This will partly be fixed by removing repeated tests. However, this points to an overarching issue where it would be best if we could completely ignore the ovs/ subtree when running tests.
During the build process, you currently must touch manpages.mk. If you do
not do this, then you will see the following errors when attempting to build:
lib/daemon-syn.man not found in: . . . lib/vlog-syn.man not found in: . . . lib/ssl-syn.man not found in: . . . lib/ssl-bootstrap-syn.man not found in: . . . lib/ssl-connect-syn.man not found in: . . . lib/common-syn.man not found in: . . . ovsdb/ovsdb-schemas.man not found in: . . . lib/table.man not found in: . . . lib/daemon.man not found in: . . . lib/vlog.man not found in: . . . lib/ssl.man not found in: . . . lib/ssl-bootstrap.man not found in: . . . lib/ssl-connect.man not found in: . . . lib/common.man not found in: . . . lib/daemon-syn.man not found in: . . . lib/service-syn.man not found in: . . . lib/vlog-syn.man not found in: . . . lib/ssl-syn.man not found in: . . . lib/ssl-bootstrap-syn.man not found in: . . . lib/ssl-peer-ca-cert-syn.man not found in: . . . lib/ssl-connect-syn.man not found in: . . . lib/unixctl-syn.man not found in: . . . lib/common-syn.man not found in: . . . lib/daemon.man not found in: . . . lib/service.man not found in: . . . lib/vlog.man not found in: . . . lib/ssl.man not found in: . . . lib/ssl-bootstrap.man not found in: . . . lib/ssl-peer-ca-cert.man not found in: . . . lib/ssl-connect.man not found in: . . . lib/unixctl.man not found in: . . . lib/common.man not found in: . . . lib/vlog-unixctl.man not found in: . . . lib/memory-unixctl.man not found in: . . . lib/coverage-unixctl.man not found in: . . . lib/vlog-syn.man not found in: . . . lib/common-syn.man not found in: . . . ovsdb/ovsdb-schemas.man not found in: . . . lib/vlog.man not found in: . . . lib/common.man not found in: . . . make: *** [Makefile:4022: manpages.mk] Error 1
These errors are cryptic. Grepping for the referenced file names gives nothing to go on, as far as I could see. For whatever reason, touching the manpages.mk file makes these errors go away. Why? Hell if I know.
As has been mentioned, aside from ensuring tests pass and the the sandbox works, other use cases are untested. For instance, it's highly likely that building packages currently does not work.
Less Obvious Improvements
There are some files in the tree that are currently specific to OVS, but removing them might not be the best choice. For instance, it might be a good idea to revise the Vagrantfile so that it is focused on installing OVN instead of installing OVS. Something similar could probably be done for files in the poc/ and xenserver/ subdirectories.
Moving the contents of the ovn/ subdirectory to the top level makes sense given the context of the new repo. However, some files that exist at the top level now may make sense to shove into a subdirectory. For instance, the ovsschema files for the north and southbound database are at the top level now. It may make sense to put them in a subdirectory.
The way include paths are handled may be a bit more slapdash than necessary. It would probably be best if OVN source files made it explicit when they were including OVN headers vs OVS headers. For instance:
#include "ovs/lib/smap.h" #include "ovs/include/openvswitch/hmap.h"
Currently, these are just done as:
#include "smap.h" #include "openvswitch/hmap.h"
Doing this would require some changes to how IDL files are auto-generated since they generate include directives with assumptions about the include path.
I didn't quite 100% grok how auto-generation of the IDL files is done. In order to build the north- and south-bound IDL C files, I ended up copying the ovsdb automake.mk file from OVS into the lib/ directory for OVN and fixing the paths. There is likely a much easier way to generate the IDL C files.
In a similar vein, there likely is a decent amount of Makefile instructions that can be removed. I didn't bother removing stuff unless it was very clear that it needed to be removed.
Running OVN in a sandbox currently works, but the way it works could be improved. It would probably be better if OVN called into the OVS script to get the OVS components started and then start the OVN components locally. Currently, the script is copied wholesale.
The commits in this repo are a mess. They are not grouped very well and they have minimal commit messages. It would be a good idea to rebase all of the commits so that they are arranged logically and have good explanations.