Phantom

Phantom listens on a port and exposes prometheus metrics about requests being posted to it.

The response will always be 200, the body content will be read and ignored.

The service will record into a counter the contents of the X-Forwarded-For header as labels called origin and proxies if available.

The address to listen to, the header to be used as origin and log levels are configurable, see usage below.

Example

# HELP metrics_posts_received_total The total number of received posts for metrics
# TYPE metrics_posts_received_total counter
metrics_posts_received_total{origin="1.2.3.4",proxies=""} 1
metrics_posts_received_total{origin="1.2.3.4",proxies="5.6.7.8"} 1
metrics_posts_received_total{origin="unknown",proxies=""} 1
metrics_posts_received_total{origin="10.0.0.1",proxies="",path="hosts.10.0.0.1.cpu.idle"} 1

Usage

Usage of ./phantom:
  -debug
    	print path information
  -header string
    	request address header (default "X-Forwarded-For")
  -listen string
    	ip:port for listening to web requests (default ":7777")
  -log.level string
    	debug, info, warn, error (default "info")

Debugging

It's useful to identify paths on this very specific use-case where the body of the request is posting JSON arrays.

When Debugging is enabled the metric exposed will include a path label with parsed value from the request body for a JSON format of:

[
  { "path" : "a.path.for.metric",
    "value" : <ignored>
    "timestamp" : <ignored>
  }
]

To toggle debugging on and off send a USR1 signal to the running process.

Local Build

go mod download && go build

Docker local build

docker build . -t phantom:local

Docker local run

docker run --rm -p 7777:7777 phanton:local

Testing

go test -v
=== RUN   TestHandler
level=debug msg="request received from origin" origin=10.1.1.1
--- PASS: TestHandler (0.00s)
=== RUN   TestEmptyBody
--- PASS: TestEmptyBody (0.00s)
PASS
ok  	github.com/marcosvm/phantom	0.316s

and

go test -bench -cpu=1,2,4,8,16,32 -run=^$ -bench ^BenchmarkPost$ github.com/marcosvm/phantom
goos: darwin
goarch: arm64
pkg: github.com/marcosvm/phantom
BenchmarkPost-10    	 2593036	       464.3 ns/op	    1135 B/op	       7 allocs/op
PASS
ok  	github.com/marcosvm/phantom	1.830s

Production and other environments

Please follow the best practices and workflows for building and publishing.

marcosvm / phantom