Neutron Ports: Add support for extra_dhcp_opts

[bugosiphionah]

For #511

Links to the line files in the OpenStack (Neutron) source code that support the code in this PR:

• https://github.com/openstack/neutron/blob/e6dc39518ccfef79ecf9beae0b3a2c094b4c220b/neutron/agent/linux/dhcp.py
• https://github.com/openstack/neutron/blob/7b4ad21cb53c57b31f093ba9f6babb8e0f27e9f6/neutron/db/extradhcpopt_db.py

[coveralls]

Coverage increased (+0.1%) to 71.796% when pulling 6435e8f on bugosiphionah:issue_511 into 273b98b on gophercloud:master.

[bugosiphionah]

@jtopjian This is ready for review.

[jtopjian]

@bugosiphionah Thanks for working on this - this is good start.

The two source code files you found are correct. In the first one, it shows further information about extra_dhcp_opts being imported:

https://github.com/openstack/neutron/blob/e6dc39518ccfef79ecf9beae0b3a2c094b4c220b/neutron/agent/linux/dhcp.py#L24

which can be found here:

https://github.com/openstack/neutron-lib/blob/master/neutron_lib/api/definitions/extra_dhcp_opt.py#L25-L44

According to that file, extra_dhcp_opts looks to have a more structured format. So I think we will need to create a special type for this. Something like:

type ExtraDHCPOpts struct {
  OptName   string                `json:"opt_name"`
  OptValue  string                `json:"opt_value"`
  IPVersion gophercloud.IPVersion `json:"ip_version"`
}

I think running some commands in a devstack environment will help a lot with implementing this PR. For example:

$ neutron help port-create
$ neutron --debug port-create --extra-dhcp-opt opt_name=tftp-server,opt_value=192.168.0.3,ip_version=4 ...

Using --debug will display the HTTP request and response bodies which will help with adding this to Gophercloud.

You can find some examples of valid DHCP options here:

https://github.com/openstack/neutron/blob/779a8d31e7afcd20671e7a09309f68339471f1d9/neutron/tests/unit/agent/linux/test_dhcp.py#L773-L804

Let me know if you have any questions :)

[coveralls]

Coverage increased (+0.3%) to 71.947% when pulling 198c6a4 on bugosiphionah:issue_511 into 273b98b on gophercloud:master.

[bugosiphionah]

@jtopjian This is ready for review.

[jtopjian]

@bugosiphionah Nice work! The new ExtraDHCPOpts struct is exactly what I had in mind :)

Please see the comments I left.

In addition, I recommend either adding a new unit test for "Create" or modifying the existing Create unit test.

For the Update unit test, I recommend creating a whole new unit test so there are two unit tests for update: one with ExtraDHCPOpts specified and one without. This way, we can test if omitempty is working correctly.

For both Create and Update unit tests, I recommend adding some values to the ExtraDHCPOpts struct instead of testing an empty struct.

You'll have to modify existing create/update fixtures and make new fixtures.

Let me know if you have any questions or need any help.

[jtopjian]

Are you sure ExtraDHCPOpts is a valid option for list operations? Can you verify this by providing the Neutron code that shows it or the equivalent neutron command?

[jtopjian]

ExtraDHCPOPTS should be ExtraDHCPOpts.

[jtopjian]

ExtraDHCPOPTS should be ExtraDHCPOpts.

[jtopjian]

ExtraDHCPOPTS should be ExtraDHCPOpts.

[jtopjian]

Remember to make sure there is a space after // in comments or the comment will not be rendered as documentation in godoc.

Also instead of using "This is..." I recommend using the field name: "ExtraDHCPOpts represents extra..."

[jtopjian]

This was implemented in #804