Pretty print json payloads in the printer function.

[welteki]

Description

Update the printer function to support pretty printing of json payloads.

If the env variable RAW=true it will print the raw payload.

How has this been tested

Deployed the printer function:

SERVER=ttl.sh OWNER=welteki faas-cli up --filter printer

Invoked the function with a json payload:

curl -i $OPENFAAS_URL/function/printer \
  -d '{ "foo": "bar", "greeting": "hello" }' \
  -H 'Content-Type: application/json'

Verified the logs to see the payload was printed correctly:

2023-12-15T17:26:00Z User-Agent=[curl/7.81.0]
2023-12-15T17:26:00Z Accept-Encoding=[gzip]
2023-12-15T17:26:00Z X-Forwarded-Host=[gw.exit.welteki.dev]
2023-12-15T17:26:00Z X-Forwarded-Proto=[https]
2023-12-15T17:26:00Z X-Start-Time=[1702661160444470811]
2023-12-15T17:26:00Z Accept=[*/*]
2023-12-15T17:26:00Z X-Forwarded-For=[94.105.108.156, 127.0.0.1]
2023-12-15T17:26:00Z X-Forwarded-Uri=[/function/printer]
2023-12-15T17:26:00Z Content-Type=[application/json]
2023-12-15T17:26:00Z X-Call-Id=[dc321b80-f5d8-4d9f-adea-5f23823abf07]
2023-12-15T17:26:00Z X-Inlets-Id=[303f46d3442a456892f74d55d51debb9]
2023-12-15T17:26:00Z 
2023-12-15T17:26:00Z {
2023-12-15T17:26:00Z     "foo": "bar",
2023-12-15T17:26:00Z     "greeting": "hello"
2023-12-15T17:26:00Z }

Verified the raw payload is printed when the env variable RAW=true
Verified the raw payload is printed if the request does not set the header Content-Type: application/json:

curl -i $OPENFAAS_URL/function/printer \
  -d '{ "foo": "bar", "greeting": "hello" }'