Use values in body sent to gateway and send them as header values to the service

[AgentGoldPaw]

Environment info:

KrakenD version: 2.5.0
System info: docker
Hardware specs: M2 mac with 64gb RAM
Backend technology: N/A
Additional environment information:
Describe what are you trying to do:
trying do what the title says. extract data from the body sent to the gateway, and use in the headers of the request to the backend service.

Your configuration file:

{
"$schema": "https://www.krakend.io/schema/krakend.json",
"version": 3,
"name": "Developer API",
"timeout": "60s",
"extra_config": {
"telemetry/logging": {
"level": "DEBUG",
"prefix": "[KRAKEND]",
"syslog": true,
"stdout": true,
"format": "logstash",
"syslog_facility": "local3"
},
"telemetry/logstash": {
"enabled": true
}
},
"timeout": "3000ms",
"cache_ttl": "300s",
"output_encoding": "json",
"debug_endpoint": true,
"echo_endpoint": true,
"endpoints": [
{
"endpoint": "/publicapi/v1/{route}",
"method": "GET",
"output_encoding": "no-op",
"backend": [
{
"url_pattern": "/publicapi/v1/{route}",
"encoding": "no-op",
"sd": "static",
"method": "GET",
"disable_host_sanitize": false,
"host": [
"https://api.localhost.com"
]
}
]
},
{
"endpoint": "/publicapi/v1/{route}",
"method": "POST",
"output_encoding": "no-op",
"backend": [
{
"url_pattern": "/publicapi/v1/{route}",
"encoding": "no-op",
"sd": "static",
"method": "POST",
"disable_host_sanitize": false,
"host": [
"https://api.localhost.com"
]
}
],
"input_headers": [
"*"
]
},
{
"endpoint": "/oauth2/authorize",
"method": "GET",
"output_encoding": "no-op",
"backend": [
{
"url_pattern": "/",
"encoding": "no-op",
"method": "GET",
"host": [
"https://signin.localhost.com"
]
}
],
"extra_config": {
"modifier/lua-proxy": {
"post": "local r = response.load(); local req = request.load(); print(req:query()); r:statusCode(301); r:headers('location', 'https://signin.localhost.com/authorize?' .. req:query())"
}
}
}
]
}

[AgentGoldPaw]

it looks like this is only possible with enterprise.... is there a trial period for enterprise so i can do a load test to see if this is something i want?

[alombarte]

Hi @AgentGoldPaw ,

You can achieve this with the open source edition. Here's an example configuration:

{
    "$schema": "https://www.krakend.io/schema/v2.5/krakend.json",
    "version": 3,
    "name": "My KrakenD API Gateway",
    "port": 8080,
    "host": ["http://localhost:8080"],
    "echo_endpoint": true,
    "endpoints": [
      {
        "endpoint": "/test",
        "method": "POST",
        "backend": [
          {
            "url_pattern": "/__echo/",
            "allow": ["req_headers"],
            "extra_config": {
                "modifier/lua-backend": {
                  "allow_open_libs": true,
                  "pre": "local r = request.load(); r:headers('X-Body1', r:body())"
                }
              }
          }
        ]
      }
    ]
  }

And the output is:

curl -XPOST -d 'hithere' http://localhost:8080/test   
{"req_headers":{"Accept-Encoding":["gzip"],"Content-Type":["application/x-www-form-urlencoded"],"User-Agent":["KrakenD Version 2.5.0"],"X-Body1":["hithere"],"X-Forwarded-For":["172.17.0.1"],"X-Forwarded-Host":["localhost:8080"]}}

If your body is in JSON or another format, you will additionally need to parse the body (because it comes as a string) if you want a specific field, but other than that you can see this is feasible in CE.

If you want to test the EE version you can get in touch with sales@krakend.io

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