cf-tcp-test-app

Test app for Cloud Foundry app lifecycle & health check debugging.

What it does

The app offers various endpoints that allow for fine control over its health state & responses on TCP level.

It also logs every request it receives, plus various lifecycle events.

/togglehealth:

Toggles App Health State and returns new app health state.

/health:

Returns a 200 if the app is healthy, drops/closes the connection otherwise.

/drop:

Always drops the Connection. Results in Gorouter error-code 502 with x_cf_routererror:"endpoint_failure (EOF (via idempotent request))".

/always_up:

Always returns a 200 response even when the app is unhealthy.

All others

Returns a 200 if the app is healthy, drops/closes the connection otherwise. Also writes the HTTP Method into the response

How to Build

go build

How to Run

Either run the binary or push it to CloudFoundry with the given manifest.yml.

Use health-check-type: process for process healthchecks, or the following for HTTP health checks:

    health-check-type: http
    health-check-http-endpoint: /health

The following environment variables affect the apps behaviour and can be specified in the manifest (see example).

INITIAL_HEALTH

If INITIAL_HEALTH: false is specified, the app will start with failing Health endpoint (i.e. cf push will fail)

Customizable Wait Periods

flowchart LR
    start["Process started"] --->|START_DELAY| listens["listener starts"] -.-|App runs| crash["SIGTERM received"] --->|DRAIN_DELAY| drain["listener stopped"] --->|STOP_DELAY| stop["Process stopped"]

START_DELAY, DRAIN_DELAY and STOP_DELAY can be set to durations, e.g. "10s", "5m".

How to use

After pushing the app to CF, use cf logs cf-tcp-test-app to see the detailed log output of every request/health-check/event.

References

• Health Check Lifecycle in CF Docs