CyberArk: Get --input-file working with machinehub mode

[wallrj-cyberark]

I wanted to get the --input-path feature working with machinehub mode. It wasn't working because the cyberark snapshot conversion requires the datareadings to have concrete types, but the existing input mode just treats the data as interface{}.

I've added tests which demo the input-file working with machinehub mode. They only run if you have the ARK_ environment variables set.

• Implemented custom JSON unmarshaling for DataReading to handle dynamic parsing of the Data field.
• Added UnmarshalJSON for GatheredResource to support strict JSON decoding.
• Introduced TestOutputModes to validate the --machine-hub mode with example configuration and input files.
• Added example files config.yaml and input.json for machinehub mode testing.

Testing

Here's an example of me running the machinehub output mode test locally.

go test -v -run='TestOutputModes$' 
...

=== RUN   TestOutputModes/machinehub
    agent_test.go:71: Running child process /tmp/go-buildXXXXXXX/b001/cmd.test -test.run=^TestOutputModes/machinehub$
    agent_test.go:80: STDOUT
        I0904 10:08:41.508879 XXXXXXX run.go:58] "Starting" logger="Run" version="development" commit=""
        I0904 10:08:41.509044 XXXXXXX config.go:448] "Output mode selected" logger="Run" mode="MachineHub" reason="--machine-hub was specified"
        I0904 10:08:41.509101 XXXXXXX run.go:116] "Healthz endpoints enabled" logger="Run.APIServer" addr=":8081" path="/healthz"
        I0904 10:08:41.509121 XXXXXXX run.go:120] "Readyz endpoints enabled" logger="Run.APIServer" addr=":8081" path="/readyz"
        I0904 10:08:41.509134 XXXXXXX run.go:269] "Pod event recorder disabled" logger="Run" reason="The agent does not appear to be running in a Kubernetes cluster." detail="When running in a Kubernetes cluster the following environment variables must be set: POD_NAME, POD_NODE, POD_UID, POD_NAMESPACE"
        I0904 10:08:41.509149 XXXXXXX run.go:308] "Reading data from local file" logger="Run.gatherAndOutputData" inputPath="/path/to/examples/machinehub/input.json"
        I0904 10:08:41.509657 XXXXXXX run.go:432] "Starting" logger="Run.APIServer.ListenAndServe" addr=":8081"
        I0904 10:08:41.813165 XXXXXXX round_trippers.go:632] "Response" logger="Run.gatherAndOutputData.postData" verb="GET" url="https://platform-discovery.integration-cyberark.cloud/api/public/tenant-discovery?bySubdomain=REDACTED" status="200 OK" milliseconds=303
        I0904 10:08:42.092198 XXXXXXX round_trippers.go:632] "Response" logger="Run.gatherAndOutputData.postData" verb="POST" url="https://REDACTED.id.integration-cyberark.cloud/Security/StartAuthentication" status="200 OK" milliseconds=278
        I0904 10:08:42.092855 XXXXXXX identity.go:292] "made successful request to StartAuthentication" logger="Run.gatherAndOutputData.postData" source="Identity.doStartAuthentication" summary="NewPackage"
        I0904 10:08:42.321967 XXXXXXX round_trippers.go:632] "Response" logger="Run.gatherAndOutputData.postData" verb="POST" url="https://REDACTED.id.integration-cyberark.cloud/Security/AdvanceAuthentication" status="200 OK" milliseconds=228
        I0904 10:08:42.322694 XXXXXXX identity.go:402] "successfully completed AdvanceAuthentication request to CyberArk Identity; login complete" logger="Run.gatherAndOutputData.postData" username="REDACTED"
        I0904 10:08:42.904233 XXXXXXX round_trippers.go:632] "Response" logger="Run.gatherAndOutputData.postData" verb="POST" url="https://REDACTED.inventory.integration-cyberark.cloud/api/ingestions/kubernetes/snapshot-links" status="200 OK" milliseconds=580
        I0904 10:08:43.335732 XXXXXXX round_trippers.go:632] "Response" logger="Run.gatherAndOutputData.postData" verb="PUT" url="https://REDACTED.s3.amazonaws.com/REDACTED.snapshot?AWSAccessKeyId=REDACTED&Signature=REDACTED&x-amz-tagging=REDACTED" status="200 OK" milliseconds=431
        I0904 10:08:43.336407 XXXXXXX run.go:417] "Data sent successfully" logger="Run.gatherAndOutputData.postData"
        I0904 10:08:43.336503 XXXXXXX run.go:446] "Shutting down" logger="Run.APIServer.ListenAndServe" addr=":8081"
        I0904 10:08:43.337512 XXXXXXX run.go:461] "Shutdown complete" logger="Run.APIServer.ListenAndServe" addr=":8081"
        
    agent_test.go:81: STDERR
        
--- PASS: TestOutputModes (1.94s)
    --- PASS: TestOutputModes/localfile (0.06s)
    --- PASS: TestOutputModes/machinehub (1.88s)
PASS
ok  	github.com/jetstack/preflight/cmd	2.014s

The test is currently skipped in CI:

• https://github.com/jetstack/jetstack-secure/actions/runs/17458740480/job/49578261718?pr=707#step:7:51

=== Skipped
=== SKIP: cmd TestOutputModes/machinehub (0.00s)
    agent_test.go:35: Skipping test because one of ARK_SUBDOMAIN, ARK_USERNAME or ARK_SECRET isn't set

=== SKIP: internal/cyberark TestCyberArkClient_PutSnapshot_RealAPI (0.00s)
    client_test.go:69: Skipping: missing environment variables: ARK_SUBDOMAIN, ARK_USERNAME, ARK_SECRET

=== SKIP: internal/cyberark/identity TestLoginUsernamePassword_RealAPI (0.00s)
    identity_test.go:53: Skipping test because one of ARK_SUBDOMAIN, ARK_USERNAME or ARK_SECRET isn't set

=== SKIP: pkg/client TestCyberArkClient_PostDataReadingsWithOptions_RealAPI/success (0.00s)
    client_cyberark_test.go:67: Skipping: missing environment variables: ARK_SUBDOMAIN, ARK_USERNAME, ARK_SECRET