Capture Mode v3.9.0

capture is replay mode plus automatic recording of upstream misses.

⚠️ EXPERIMENTAL FEATURE: capture mode is part of the experimental upstream modes feature set and may change without notice.

Behavior

For each request:

1. Try local stub match first.
2. If local match exists, return local response.
3. If no local match, forward request to upstream.
4. Record upstream response/error as a local stub.

Recorded stubs are immediately available for later local replay.

What gets recorded

Capture stores request and upstream result in stub form:

• request input (input/inputs)
• request headers (filtered user headers)
• response data/stream
• grpc error code/message/details (when present)
• response headers
• session context (if present)

URL schemes

• grpc+capture://host:port
• grpcs+capture://host:port

Query parameters

Parameter	Default	Description
timeout	5s	Timeout for upstream requests.
bearer	—	Bearer token to include in upstream requests.
serverName	—	Override TLS server name (SNI).
insecureSkipVerify	false	Skip upstream TLS certificate verification.
recordDelay	false	Record response latency as delay in captured stubs.

Example with delay recording enabled:

GRPC_PORT=4770 HTTP_PORT=4771 gripmock "grpc+capture://orders.api.local:4770?recordDelay=true"

Order Service example

Goal: quickly mock OrderService with minimal manual stub authoring.

Start capture mode against the real upstream:

GRPC_PORT=4770 HTTP_PORT=4771 gripmock "grpcs+capture://orders.api.local:8443?serverName=orders.api.local"

Then point your application/test environment to localhost:4770 and run normal workflows.

Runtime effect:

• matched local stubs are reused;
• unmatched requests are proxied to upstream;
• upstream responses/errors are recorded into GripMock storage.

After enough traffic, you get broad local coverage and can switch environments to replay/local-first behavior.

When to choose capture

• You need fastest bootstrap for large or legacy services.
• You want to convert real traffic into reusable stubs.
• You want to replace upstream dependency progressively with local mocks.