GOV.UK PaaS LogCacheAdapter

Application for collecting metrics from GOV.UK PaaS via log-cache in the following formats:

• Prometheus text format

How to run

This application requires the log-cache API URL to be provided. It can be passed in as LOG_CACHE_API environment variable or as -log-cache-api / -a flag.

make run
# or
go run main.go handlers.go middleware.go server.go utils.go # make sure to list all files

Available flags

Environment Variable	Flag	Description	Default
LOG_CACHE_API	-log-cache-api, -a	Required. The log-cache API URL.	N/A
PORT	-port, -p	The port server should be running on.	"8080"
DEBUG	-verbose, -v	Run the server in debugging mode.	"false"

Testing

To run test, simply execute the following command:

make test

If you run into problems with go test caching, set the enviornment variable GOCACHE=off.

API

The application exposes single endpoint, /metrics - root. It requires two headers to be provided, in order for it to work as expected. These are:

Accept header

Which tells the application at what format would you like to receive the logs. Currently only one formats is recognised:

• Prometheus: text/plain

Authorization header

In format of:

bearer ${JWT_WEB_TOKEN}

Which tells the application, what metrics should you have access to.

It can work to your advantage, if you create an user with restricted access, to target only the applications and instances you want.

For instance, you can obtain that token with the use of CLI command:

cf oauth-token

Example

If you put everything together and execute the following curl command:

curl -H "Accept: text/plain" -H "Authorization: $(cf oauth-token)" http://localhost:8080/

You should retreive the Prometheus text of different metrics your user has access to.