gvso / configurable-server-response

Configurable Server Response

This is a simple webservice that have configurable parameters for 500 errors and latency to allow manipulating the values needed to test things like metrics.

This was initially built to test metrics for GoogleCloudPlatform/cloud-run-release-manager.

Environment variables

The following environment variables are used to determine the webservice's behavior:

• PERCENT_500_RESPONSES: Percentage of requests that would received an HTTP 500 error
• LATENCY_P99: The minimum latency for the 99th percentile (in ms).
• LATENCY_P95: The minimum latency for the 95th percentile (in ms).
• LATENCY_P50: The minimum latency for the 50th percentile (in ms).

Turning environment variables on/off

The above environment variables can be turned off at the beginning to test a healthy service, and then turned on to start the behavior set with the variables in the above section.

For this, this web service relies on the Runtime Configurator:

1. Create Runtime Configurator resource:

   gcloud beta runtime-config configs create [CONFIG_NAME]

2. Set a variable on whether the behavior set the by the environment variables above should be followed:

   gcloud beta runtime-config configs variables set respect-variables \
   "no" --config-name [CONFIG_NAME] --is-text

3. Update this webservice's environment variable, so it knows which runtime configurator resource and variables to use.

   gcloud run services update [SERVICE] \
     --update-env-vars PROJECT=<YOUR_PROJECT>,CONFIG_NAME=<CONFIG_NAME>

4. Starts sending requests to your service (e.g. using hey).

5. Once you want your service to respect the environment variables set in the above section, update the Runtime Configurator resource's variable to yes:

     gcloud beta runtime-config configs variables set respect-variables \
       "yes" --config-name [CONFIG_NAME] --is-text