O-RAN-SC Non-RealTime RIC CAPIF Core implementation

This product is a Go implementation of the CAPIF Core function, based on the 3GPP "29.222 Common API Framework for 3GPP Northbound APIs (CAPIF)" interfaces, see https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=3450.

The, almost, complete data model for CAPIF is shown in the diagram below.

The data used within CAPIF Core for registering rApps that both provides and consumes services is shown in the diagram below.

Some examples of interactions between components using the CAPIF interface are shown in the sequence diagram below.

NOTE! It has not been decided that CAPIF Core will actually do the Helm chart installation. This is just provided in the prototype as an example of what CAPIF Core could do.

If Helm is used, before publishing a service, the chart that belongs to the service must be registered in ChartMuseum. When publishing the service the following information should be provided in the ServiceAPIDescription::description attribute; "namespace", "repoName", "chartName", "releaseName". An example of the information: "Description of rApp helloWorld,namespace,repoName,chartName,releaseName".

Generation of API code

The CAPIF APIs are generated from the OpenAPI specifications provided by 3GPP. The generate.sh script downloads the specifications from 3GPP, fixes them and then generates the APIs. It also generates the mocks needed for unit testing. The specifications are downloaded from the following site; https://www.3gpp.org/ftp/Specs/archive/29_series. To see the APIs in swagger format, see the following link; https://github.com/jdegre/5GC_APIs/tree/Rel-16#common-api-framework-capif. NOTE! The documentation in this link is for release 16 of CAPIF, the downloaded specifications are for release 17.

To fix the specifications there are three tools:

• commoncollector, collects type definitions from peripheral specifications to keep down the number of dependencies to other specifications. The types to collect are listed in the definitions.txtfile. Some fixes are hard coded.
• enumfixer, fixes enumeration definitions so they can be properly generated.
• specificationfixer, fixes flaws in the specifications so they can be properly generated. All fixes are hard coded.

Steps to add a new dependency to the commoncollector

When a dependency to a new specification is introduced in any of the CAPIF specifications, see example below, the following steps should be performed:

For the CAPIF specification "TS29222_CAPIF_Discover_Service_API" a new dependency like the following has been introduced.

websockNotifConfig:
    $ref: ✅TS29122_CommonData.yaml#/components/schemas/WebsockNotifConfig✅'

1. Copy the part between the checkboxes of the reference and add it to the definitions.txt file. This step is not needed if the type is already defined in the file.
2. Look in the generate.sh script, between the "<replacements_start>" and "<new_replacement>" tags, to see if "TS29122_CommonData" has already been replaced in "TS29222_CAPIF_Discover_Service_API".
3. If it has not been replaced, add a replacement above the "<new_replacement>" tag by copying and adapting the two rows above the tag.

Build and test

To generate mocks manually, run the following command:

go generate ./...

NOTE! The helmmanagement package contains two mocks from the helm.sh/helm/v3 product. If they need to be regenerated, their interfaces must be copied into the helm.go file and a generation annotation added before running the generation script.

To build the application, run the following command:

go build

To run the unit tests for the application, run the following command:

go test ./...

The application can also be built as a Docker image, by using the following command:

docker build . -t capifcore

Run

To run the Core Function from the command line, run the following commands from this folder. For the parameter chartMuseumUrl, if it is not provided CAPIF Core will not do any Helm integration, i.e. try to start any Halm chart when publishing a service.

./capifcore [-port <port (default 8090)>] [-secPort <Secure port (default 4433)>] [-chartMuseumUrl <URL to ChartMuseum>] [-repoName <Helm repo name (default capifcore)>] [-loglevel <log level (default Info)>] [-certPath <Path to certificate>] [-keyPath <Path to private key>]

To run CAPIF Core as a K8s pod together with ChartMuseum, start and stop scripts are provided. The pod configurations are provided in the configs folder. CAPIF Core is then available on port 31570.