Compress otlp payload with zlib

Fixes #71

Also updates the otel-collector configuration file:

* The `logging` exporter was renamed to `debug`
* Jaeger now supports receiving OTLP traffic which makes things simpler

Dockerfile

@@ -1,9 +1,10 @@
 FROM openresty/openresty:1.21.4.1-0-centos
 
-RUN yum install -y gcc
+RUN yum install -y gcc git zlib-devel
 RUN yum -y --enablerepo=powertools install libyaml-devel libffi-devel
 RUN luarocks install lua-resty-http 0.16.1-0
 RUN luarocks install lua-protobuf 0.3.3
+RUN luarocks install lua-zlib 1.2
 RUN luarocks install busted 2.0.0-1
 RUN luarocks --server=http://rocks.moonscript.org install lyaml
 

docker-compose.yml

@@ -17,20 +17,23 @@ services:
     image: jaegertracing/all-in-one
     ports:
       - 26686:16686
+      - 4319-4320:4317-4318
     networks:
       - opentelemetry-lua
   otel-collector:
     image: otel/opentelemetry-collector-contrib-dev:latest
     command: [ "--config=/etc/otel-collector-config.yaml" ]
+    ports:
+      - 4317:4317
     volumes:
       - ./otel-collector-config.yaml:/etc/otel-collector-config.yaml
-    depends_on:
-      - jaeger
     networks:
       - opentelemetry-lua
   test-server:
     build:
       context: ./examples/server
+    ports:
+      - 10080:80
     depends_on:
       - otel-collector
     networks:

lib/opentelemetry/trace/exporter/http_client.lua

@@ -1,5 +1,5 @@
 local http = require("resty.http")
-
+local zlib = require("zlib")
 local _M = {
 }
 
@@ -13,9 +13,10 @@ local mt = {
 -- @address             opentelemetry collector: host:port
 -- @timeout             export request timeout second
 -- @headers             export request headers
+-- @httpc               openresty http client instance
 -- @return              http client
 ------------------------------------------------------------------
-function _M.new(address, timeout, headers)
+function _M.new(address, timeout, headers, httpc)
     headers = headers or {}
     headers["Content-Type"] = "application/x-protobuf"
 
@@ -28,29 +29,43 @@ function _M.new(address, timeout, headers)
         uri = uri,
         timeout = timeout,
         headers = headers,
+        httpc = httpc,
     }
     return setmetatable(self, mt)
 end
 
-function _M.do_request(self, body)
-    local httpc = http.new()
-    httpc:set_timeout(self.timeout * 1000)
+function _M.do_request(self, body, encode_gzip)
+    self.httpc = self.httpc or http.new()
+
+    encode_gzip = encode_gzip or false
+    self.httpc:set_timeout(self.timeout * 1000)
+
+    if encode_gzip then
+        -- Compress (deflate) request body
+        -- the compression should be set to Best Compression and window size
+        -- should be set to 15+16, see reference below:
+        -- https://github.com/brimworks/lua-zlib/issues/4#issuecomment-26383801
+        self.headers["Content-Encoding"] = "gzip"
+        local deflate_stream = zlib.deflate(zlib.BEST_COMPRESSION, 15+16)
+        local compressed_body = deflate_stream(body, "finish")
+        body = compressed_body
+    end
 
-    local res, err = httpc:request_uri(self.uri, {
+    local res, err = self.httpc:request_uri(self.uri, {
         method = "POST",
         headers = self.headers,
         body = body,
     })
 
     if not res then
         ngx.log(ngx.ERR, "request failed: ", err)
-        httpc:close()
+        self.httpc:close()
         return nil, err
     end
 
     if res.status ~= 200  then
         ngx.log(ngx.ERR, "request failed: ", res.body)
-        httpc:close()
+        self.httpc:close()
         return nil, "request failed: " .. res.status
     end
 

lib/opentelemetry/trace/exporter/otlp.lua

@@ -55,7 +55,7 @@ local function call_collector(exporter, pb_encoded_body)
         end
 
         -- Make request
-        res, res_error = exporter.client:do_request(pb_encoded_body)
+        res, res_error = exporter.client:do_request(pb_encoded_body, true)
         local after_time = util.gettimeofday_ms()
         otel_global.metrics_reporter:record_value(
             exporter_request_duration_metric, after_time - current_time)

otel-collector-config.yaml

@@ -9,15 +9,10 @@ exporters:
     endpoint: "0.0.0.0:8889"
     const_labels:
       label1: value1
-  logging:
-    loglevel: debug
-
-  #zipkin:
-  #  endpoint: "http://zipkin-all-in-one:9411/api/v2/spans"
-  #  format: proto
-
-  jaeger:
-    endpoint: jaeger:14250
+  debug:
+    verbosity: detailed
+  otlp/jaeger:
+    endpoint: jaeger:4317
     tls:
       insecure: true
 
@@ -37,8 +32,8 @@ service:
     traces:
       receivers: [otlp]
       processors: [batch]
-      exporters: [logging, jaeger]
+      exporters: [debug, otlp/jaeger]
     metrics:
       receivers: [otlp]
       processors: [batch]
-      exporters: [logging, prometheus]
+      exporters: [debug, prometheus]

rockspec/opentelemetry-lua-master-0.rockspec

@@ -14,6 +14,7 @@ description = {
 dependencies = {
     "lua-protobuf = 0.3.3",
     "lua-resty-http = 0.16.1-0",
+    "lua-zlib = 1.2",
 }
 
 build = {

spec/trace/exporter/http_client_spec.lua

@@ -0,0 +1,57 @@
+local http = require("resty.http")
+local client = require "opentelemetry.trace.exporter.http_client"
+local zlib = require("zlib")
+
+describe("export_spans", function()
+    it("invokes an HTTP request", function ()
+        local httpc = http.new()
+        spy.on(httpc, "request_uri")
+        local c = client.new("http://localhost:8080", 10, nil, httpc)
+        local expected_headers = {}
+        expected_headers["Content-Type"] = "application/x-protobuf"
+
+        c:do_request("Hello, World!")
+        assert.spy(httpc.request_uri).was_called_with(
+            match.is_truthy(), -- TODO(wperron) this *should* be the same ref, why is it not?
+            match.is_equal("http://localhost:8080/v1/traces"),
+            match.is_all_of(
+                match.is_table(),
+                match.is_same({
+                    method = "POST",
+                    headers = expected_headers,
+                    body = "Hello, World!"
+                })
+            )
+        )
+    end)
+
+    it("compresses the body when asked to", function ()
+        local httpc = http.new()
+        spy.on(httpc, "request_uri")
+        local c = client.new("http://localhost:8080", 10, nil, httpc)
+        local expected_headers = {}
+        expected_headers["Content-Type"] = "application/x-protobuf"
+        expected_headers["Content-Encoding"] = "gzip"
+        local expected_body = string.fromhex("1F8B0800000000000203F348CDC9C9D75108CF2FCA49510400D0C34AEC0D000000")
+
+        c:do_request("Hello, World!", true)
+        assert.spy(httpc.request_uri).was_called_with(
+            match.is_truthy(), -- TODO(wperron) this *should* be the same ref, why is it not?
+            match.is_equal("http://localhost:8080/v1/traces"),
+            match.is_all_of(
+                match.is_table(),
+                match.is_same({
+                    method = "POST",
+                    headers = expected_headers,
+                    body = expected_body
+                })
+            )
+        )
+    end)
+end)
+
+function string.fromhex(str)
+    return (str:gsub('..', function (cc)
+        return string.char(tonumber(cc, 16))
+    end))
+end

spec/trace/exporter/otlp_spec.lua

@@ -17,7 +17,7 @@ describe("export_spans", function()
         stub(ngx, "log")
         cb:export_spans({ span })
         ngx.log:revert()
-        assert.spy(c.do_request).was_called_with(c, match.is_string())
+        assert.spy(c.do_request).was_called_with(c, match.is_string(), match.is_all_of(match.is_boolean(), match.is_equal(true)))
     end)
 
     it("doesn't invoke protected_call when failures is equal to retry limit", function()