How to register app from private repo in Spring Cloud dataflow 2.6.1 - spring-cloud

Question

I'm using SCDF 2.6.1 in Openshift 3, and I'm facing error while registering the app, error log like below :
java.lang.NullPointerException: null
at org.springframework.cloud.dataflow.configuration.metadata.container.DefaultContainerImageMetadataResolver.getRegistryRequest(DefaultContainerImageMetadataResolver.java:162)
at org.springframework.cloud.dataflow.configuration.metadata.container.DefaultContainerImageMetadataResolver.getImageLabels(DefaultContainerImageMetadataResolver.java:110)
at org.springframework.cloud.dataflow.configuration.metadata.BootApplicationConfigurationMetadataResolver.resolvePortNamesFromContainerImage(BootApplicationConfigurationMetadataResolver.java:215)
at org.springframework.cloud.dataflow.configuration.metadata.BootApplicationConfigurationMetadataResolver.listPortNames(BootApplicationConfigurationMetadataResolver.java:163)
at org.springframework.cloud.dataflow.server.controller.AppRegistryController.getInfo(AppRegistryController.java:193)
at org.springframework.cloud.dataflow.server.controller.AppRegistryController.info(AppRegistryController.java:162)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
I checked the line of code in DefaultContainerImageMetadataResolver.java:162
// Convert the image name into a well-formed ContainerImage
ContainerImage containerImage = this.containerImageParser.parse(imageName);
// Find a registry configuration that matches the image's registry host
RegistryConfiguration registryConf = this.registryConfigurationMap.get(containerImage.getRegistryHost());
// Retrieve a registry authorizer that supports the configured authorization type.
RegistryAuthorizer registryAuthorizer = this.registryAuthorizerMap.get(registryConf.getAuthorizationType());
I'm pretty sure the error is because registryConf is null as result from
RegistryConfiguration registryConf = this.registryConfigurationMap.get(containerImage.getRegistryHost());
How to put my private repo URI in registryConfigurationMap ?
I have tried to put imagePullSecret in the deployment.yml which is registered with the private repo, but I think it doesn't work because in the startup log, I still see :
2020-09-03 04:55:24.111 INFO 1 --- [ main] urationMetadataResolverAutoConfiguration :
Final Registry Configurations: {registry-1.docker.io=RegistryConfiguration{registryHost='registry-1.docker.io', user='null', secret='****'', authorizationType=dockeroauth2, manifestMediaType='application/vnd.docker.distribution.manifest.v2+json', disableSslVerification='false',
extra={registryAuthUri=https://auth.docker.io/token?service=registry.docker.io&scope=repository:{repository}:pull&offline_token=1&client_id=shell }}}

Answer 1

The only place where SCDF server downloads the container image layer is when it looks for app metadata.
Currently, this is configured to use the docker registry host (as this is where all the out-of-the-box applications are hosted).
If you want to override, you can modify these property values at the time of server startup and proceed.
Remember the fact that this configuration is only needed to download the app metadata layer of the image - not to download the entire container image at the SCDF server side.