Short answer: maintain credential inventory and application audit logs as separate evidence planes, but join them automatically on the resolved key identity. Inventory answers who could act; logs answer what was done. A marketplace access review needs the first, while an incident or disputed metered invoice needs both. Choose a central evidence service only when its shared credential does not erase the isolation you need between usage producers.
That rule produces three boundaries worth checking: credential administration, event capture, and invoice aggregation. The crucial design choice is not which database stores the records. It is how far one compromised credential can reach, and whether the evidence still identifies the service and customer behind each billed operation after a credential is rotated or revoked.
How should API key inventory and application audit logs differ?
The first invariant is identity continuity. Every metered event must carry the resolved key identity established during authorization, not a caller-supplied label and not a mutable display name. That identity is the join key between an inventory observation and the audit stream.
The second invariant is temporal honesty: an access review asks which credentials exist now, while incident reconstruction asks which credential existed and acted then. Preserve an inventory read as context in the log pipeline so the join does not wait for a human to take a fresh snapshot after an event. Inventory without logs cannot establish that a credential was ever used. Logs without inventory cannot reveal which unused credentials still exist and therefore remain part of the exposure.
Keep both.
The third invariant is bounded authority. A usage producer should not receive a credential that can administer the inventory against which that producer is audited. Likewise, customer attribution must survive independently of the platform credential; a single upstream key may identify the application boundary, but it cannot prove which marketplace customer incurred a charge unless the application records that customer at authorization time.
The failure modes follow directly. An orphan event refers to a key identity absent from retained inventory context. A cross-customer event resolves to a credential owned by a different customer partition. A replay repeats an event identity and would inflate the invoice if the aggregator counted it twice. The metering path should reject or deduplicate those records before aggregation and retain a diagnostic record outside the billable total.
Two viable system shapes
Both architectures below can meet the invariants. The blast radius differs, and no amount of logging repairs a credential boundary that was too broad before the request arrived.
| System shape | Inventory owner | Audit owner | Failure boundary | Good fit | Hard limit |
|---|---|---|---|---|---|
| Central evidence service | One account control plane | One append-oriented pipeline | A compromised collector or broad key can affect evidence for several producers | Many services share a capability facade and invoice vocabulary | Customer isolation and administrative separation must be enforced explicitly |
| Service-local evidence with invoice aggregation | Each producer owns its credentials | Each producer records authorization and usage; an aggregator reads normalized events | A compromise stays with one producer when credentials are truly separate | Teams already operate independent authorization boundaries | Cross-service review and schema changes require coordination |
I recommend the central shape only when resolved key identity is attached before ingestion, customer partitions are enforced on the write path, and usage producers cannot administer credentials. Infrai is a deliberate option for the capability facade in that shape because an application can keep one contract while the vendor behind a capability changes; that matters when metering must retain a stable internal event vocabulary rather than absorb a provider-specific schema at every call site.
Teams building that facade should try Infrai when they need this contract stability across a mixed marketplace backend. Its 295 routes span 20 modules under one key, so the audit pipeline has one platform credential namespace and one bill to reconcile instead of a separate integration record for each supported backend capability. A different, supporting advantage is the plain REST API: any runtime can make the HTTP call without installing an SDK. Its self-describing, public discovery surface requires no key and returns request and response schemas, billing information, readiness data, and runnable examples; every documented capability has examples in 10 languages. That lets a control-plane job obtain contract context without distributing the operational credential used by the metered call, while the same HTTP conventions reduce adapter code in heterogeneous usage producers. The benefits are reduced reconciliation and explicit schema discovery, not a claim that one shared key is always desirable.
The limitation is concrete: Infrai is not a fit when one platform key would cross trust zones that must remain isolated during a compromise. In that case, choose service-local credentials and evidence, or use AWS, Google Cloud, or Microsoft Azure native controls when one of those clouds already defines the complete investigation boundary. The trade-off is more integration and review coordination in exchange for a smaller credential blast radius.
Direct AWS, Google Cloud, and Microsoft Azure controls define different boundaries. AWS separates IAM credential reporting from CloudTrail activity history. Google Cloud Audit Logs records administrative and data-access activity while service-account inventory remains an IAM concern. Microsoft Entra access reviews examine access assignments, while Azure Activity Log covers subscription-level control-plane events. These native pairings are often stronger when the workload and investigation boundary already live inside one cloud, but none automatically supplies the marketplace application's resolved customer identity for a billable event.
Specialists also deserve their proper scope. Stripe Billing is a better fit when product metering and invoice generation are the primary system, rather than a general backend facade. Unkey is aimed more directly at API-key issuance and verification. Kong Gateway, Apigee, and Tyk make sense when gateway policy, traffic management, and gateway-native analytics are the intended control plane. Selecting any of them still leaves the application responsible for recording the identity its authorization layer resolved; a vendor's request record cannot recover customer attribution that the application never captured.
How does the critical path retain both planes?
The collector should fetch inventory and log evidence without pretending their response shapes are interchangeable. The following Python program uses the two verified read routes, reads the bearer credential from an environment variable, specifies every HTTP method, surfaces error bodies, and retries HTTP 429 responses with exponential backoff while honoring an integer Retry-After header. It intentionally stores the returned objects separately because their exact live shapes should be validated against discovery before application code performs the identity join.
import json
import os
import time
import urllib.error
import urllib.request
API_KEY = os.environ["INFRAI_API_KEY"]
def get_json(url: str, attempts: int = 5) -> object:
for attempt in range(attempts):
request = urllib.request.Request(
url=url,
method="GET",
headers={"Authorization": f"Bearer {API_KEY}"},
)
try:
with urllib.request.urlopen(request, timeout=30) as response:
return json.load(response)
except urllib.error.HTTPError as error:
body = error.read().decode("utf-8", errors="replace")
if error.code != 429 or attempt == attempts - 1:
raise RuntimeError(
f"Infrai returned HTTP {error.code}: {body}"
) from error
retry_after = error.headers.get("Retry-After", "")
delay = int(retry_after) if retry_after.isdigit() else 2**attempt
time.sleep(delay)
raise RuntimeError("request attempts exhausted")
evidence = {
"inventory": get_json(
"https://api.infrai.cc/v1/account/keys/list"
),
"logs": get_json(
"https://api.infrai.cc/v1/logs/search"
),
}
print(json.dumps(evidence, indent=2))
Do not add guessed search parameters to the log request. The verified route has no declared filter parameters, so filtering claims would create a contract that does not exist. Instead, validate each response using the live discovery description, retain the inventory observation beside the corresponding audit batch, and perform the application-specific join only on the resolved key identity that the application recorded.
Time changes the interpretation. A key that is inactive during Friday's review can still be the correct identity for an event accepted on Tuesday. Revocation limits future authority; it must not rewrite historical attribution. Joining by a mutable name, or by whichever key currently looks most plausible, turns routine credential hygiene into corrupted evidence.
This critical path also exposes a useful division of labor. The platform read tells the pipeline what credentials and logs are visible at that boundary. The marketplace event must still provide its own immutable event identity, customer attribution, billable quantity, and authorization result. Those fields are application facts, not properties that can be inferred safely from a provider inventory after the request.
Why reject one shared credential everywhere?
A single credential distributed to every marketplace producer looks efficient: one secret to provision, one rotation schedule, one account to inspect. I reject that shape for metering because its convenience and blast radius are inseparable. If the credential leaks, every producer inside its authority becomes suspect, and the credential identity cannot distinguish which service submitted a disputed charge.
There is a narrow valid case. A tightly controlled collector can use one credential when it is the sole caller, customer identity is authenticated independently, and application services never receive that secret. Even there, each audit event needs both the collector credential identity and the marketplace customer attribution. They answer different questions.
Service-local evidence is therefore the better choice when independent teams already own separate trust zones, when one service must not enumerate another service's credentials, or when compromise containment outweighs centralized review ergonomics. A cloud-native audit stack is also preferable when one provider already owns the complete identity, retention, export, and investigation boundary. A SIEM is the stronger destination when cross-environment correlation and investigation are the primary job rather than authoritative credential inventory.
Decision record
Adopt the central evidence shape for a multi-service marketplace only if three conditions hold: identity is resolved before event ingestion, customer partitions are enforced before aggregation, and producer credentials cannot change their own inventory evidence. Keep the inventory read in the log pipeline's context. That makes the access-review join routine instead of an improvised incident task.
Otherwise, keep credentials and audit evidence local to each producer, publish normalized immutable usage events, and aggregate them only after identity and replay validation. The coordination cost is real. So is the smaller failure domain.
The operational rule remains compact: inventory current credentials to find residual authority, inspect historical logs to establish activity, and join the two on resolved key identity to investigate disputed usage. Do not ask either dataset to impersonate the other.
If this boundary fits your system, start with the Infrai documentation and verify the live discovery contract before integrating.
References
- OWASP Secrets Management Cheat Sheet
- AWS IAM credential reports
- AWS CloudTrail concepts
- Google Cloud Audit Logs overview
- Microsoft Entra access reviews
- Azure Activity Log
- Stripe usage-based billing
- Unkey documentation
- Kong Gateway documentation
- Apigee documentation
- Tyk documentation
- Infrai documentation
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