Have you ever thought that it would be great if there were a couple of envoy examples that used LUA to do something real and began to at least approach what might be considered a realistic use case?
This repo aims to show:
- Inline lua examples that execute on every request
- Lua examples that use the LuaPerRoute setup to execute on specific routes
- Included lua addons to extend the base functaionlity
- A simple translation that converts xml->json and then json->xml if the appropriate headers are set
- A library that's referenced from the code so that everything isn't embedded
as a monster inside the
envoy.yamlfile. - A simple docker-compose setup to make it all work
So checkout this repo and then run:
docker-compose build && docker-compose upThat's it. If you'd like to turn on debug logging then edit the docker
composition and change: LOGLEVEL to debug
proxy:
build:
context: .
dockerfile: ./Dockerfile-envoy
environment:
LOGLEVEL: "debug"Once it's up you can test it
Running the following will send a get request to httpbin.org and then add
a new header called X-Apigee-Bar which is just a dynamic copy of the user-agent.
Run it like so:
docker exec -it envoy-filter-experiments_proxy_1 curl http://localhost:10000/getwhich should yield something like:
{
"args": {},
"headers": {
"Accept": "*/*",
"Host": "httpbin.org",
"User-Agent": "curl/7.58.0",
"X-Amzn-Trace-Id": "Root=1-606de78c-1e4a4e15124016f82293e01f",
"X-Apigee-Bar": "curl/7.58.0",
"X-Envoy-Expected-Rq-Timeout-Ms": "15000"
},
"origin": "1.2.3.4",
"url": "http://httpbin.org/get"
}If you'd like to test a post and a dynamic conversion of xml -> json then then back again run something like this:
docker exec -it envoy-filter-experiments_proxy_1 curl -i http://localhost:10000/post -X POST -d '<xml><foo>bar</foo></xml>' -H "content-type: application/xml" -H "Accept: application/xml"
Which yields:
<body>
<args>
</args>
<origin>1.2.3.4</origin>
<url>http://httpbin.org/post</url>
<headers>
<X-Envoy-Expected-Rq-Timeout-Ms>15000</X-Envoy-Expected-Rq-Timeout-Ms>
<User-Agent>curl/7.58.0</User-Agent>
<X-Amzn-Trace-Id>Root=1-606de87f-49b9391d5ad7c47928347487</X-Amzn-Trace-Id>
<Content-Length>21</Content-Length>
<Content-Type>application/json</Content-Type>
<Accept>application/xml</Accept>
<Host>httpbin.org</Host>
</headers>
<data>{"xml":{"foo":"bar"}}</data>
<json>
<xml>
<foo>bar</foo>
</xml>
</json>
<files>
</files>
<form>
</form>
</body>Running it with an accept header of appliation/json will keep it all in json as expected.
docker exec -it envoy-filter-experiments_proxy_1 curl -i http://localhost:10000/post -X POST -d '<xml><foo>bar</foo></xml>' -H "content-type: application/xml" -H "Accept: application/json"
And yields:
{
"args": {},
"data": "{\"xml\":{\"foo\":\"bar\"}}",
"files": {},
"form": {},
"headers": {
"Accept": "application/json",
"Content-Length": "21",
"Content-Type": "application/json",
"Host": "httpbin.org",
"User-Agent": "curl/7.58.0",
"X-Amzn-Trace-Id": "Root=1-606de89e-5805b64047517ba04082bd9a",
"X-Envoy-Expected-Rq-Timeout-Ms": "15000"
},
"json": {
"xml": {
"foo": "bar"
}
},
"origin": "1.2.3.4",
"url": "http://httpbin.org/post"
}And what if you wanted to setup a GET request that transforms the request to a
SOAP/POST? This example does just that. The backend is not a real SOAP service,
but it does send a real SOAP request to the mocked backend. I simply copied
the currencies example available online. In the future I may redeploy a real SOAP
service i've used in the past and connect this to that backend. It changes nothing
about the capabilities illustrated in this example.
Maybe you don't want any code in envoy.yaml at all. That's easily accomplished by specifying the source like so:
source_codes:
xform.lua:
filename: ./xform.luaThe xform.lua script still uses the same envoy_on_request and envoy_on_response
stream handlers to do its work. However, in this final case we're also taking an
inbound GET request, transforming it to a POST and then sending a SOAP payload.
Then, if the Accept header is set to application/json the response is converted
to json before sending back.
That example is executed like so:
docker exec -it envoy-filter-experiments_proxy_1 curl -i http://localhost:10000/xform -H "accept: application/json"And yields:
{"ArrayOfString":{"_attr":{"xmlns":"http://tempuri.org/","xmlns:xsd":"http://www.w3.org/2001/XMLSchema","xmlns:xsi":"http://www.w3.org/2001/XMLSchema-instance"},"string":["AED","AFN","ALL","AMD","ANG","AOA","ARS","AUD","AWG","AZN","BAM","BBD","BDT","BGN","BHD","BIF","BND","BOB","BRL","BSD","BWP","BYN","BZD","CAD","CDF","CHF","CLP","CNY","COP","CRC","CUP","CVE","CYP","CZK","DJF","DKK","DOP","DZD","EEK","EGP","ERN","ETB","EUR","FJD","GBP","GEL","GHS","GIP","GMD","GNF","GTQ","GYD","HKD","HNL","HRK","HTG","HUF","IDR","ILS","INR","IQD","IRR","ISK","JMD","JOD","JPY","KES","KGS","KHR","KMF","KRW","KWD","KZT","LAK","LBP","LKR","LRD","LSL","LTL","LVL","LYD","MAD","MDL","MGA","MKD","MMK","MNT","MOP","MRO","MRU","MTL","MUR","MVR","MWK","MXN","MYR","MZN","NAD","NGN","NIO","NOK","NPR","NZD","OMR","PAB","PEN","PGK","PHP","PKR","PLN","PYG","QAR","RON","RSD","RUB","RWF","SAR","SBD","SCR","SDG","SEK","SGD","SIT","SKK","SLL","SOS","SRD","SSP","STN","SVC"]}}What if you need to grab an incoming request, make another request in flight, use some part of that response and add it to the next requst. Like say for a login. Well this login example shows that.
The login.lua script uses the same apigee proxy from the previous example to make
a call (a POST), grab that output and then add it to a header. This obviously
could be an actual login, but in this case it's just showing the basic flow.
The key is this piece in the envoy_on_request method:
local h,b = rh:httpCall(
"apigee",
{
[":method"] = "POST",
[":path"] = "/foobar/snarf",
[":authority"] = "emea-poc15-test.apigee.net",
["accept"] = "application/json",
["Content-Type"] = "application/json"
},
"{\"msg\": \"I am a little teapot\" }",
0)That makes an additional callout to another envoy defined cluster: apigee
Execute like so:
docker exec -it envoy-filter-experiments_proxy_1 curl -i http://localhost:10000/calloutAnd that yields the following:
{
"args": {},
"headers": {
"Accept": "*/*",
"Host": "httpbin.org",
"User-Agent": "curl/7.58.0",
"X-Amzn-Trace-Id": "Root=1-6076d847-120b2e2c3036e57a3fdf4ccd",
"X-Apigee-Message": "I am a little teapot",
"X-Envoy-Expected-Rq-Timeout-Ms": "15000",
"X-Envoy-Original-Path": "/callout"
},
"origin": "1.2.3.4",
"url": "http://httpbin.org/get"
}We could obviously do a lot more, but I think this repo shows it's possible to build real, body-touching examles with envoy that shoudld be able to accomplish at least simple mediation.