workaround to #24 with envoy filter + adapter http endpoint.

container/Dockerfile

@@ -3,7 +3,7 @@
 # - https://dev.to/ivan/go-build-a-minimal-docker-image-in-just-three-steps-514i
 #
 # Build from repo root dir with:
-# 
+#
 #     $ docker build -t boost/orionadapter -f container/Dockerfile .
 #
 FROM golang:1.13.4-stretch AS builder
@@ -14,7 +14,7 @@ ENV GO111MODULE=on \
 # NOTES.
 # 1. Modules. Without telling the complier explicitly, the build will fail.
 # I wonder why I don't have to set that var when I build on MacOS though...
-# 2. CGO. We're not using any C libs from our Go code so we disable CGO. 
+# 2. CGO. We're not using any C libs from our Go code so we disable CGO.
 # Strangely enough, without doing this explicitly, I get this error when
 # running the container:
 #
@@ -55,12 +55,12 @@ FROM scratch
 COPY --chown=0:0 --from=builder /dist /
 
 # Set up the app to run as a non-root user inside the /data folder
-# User ID 65534 is usually user 'nobody'. 
+# User ID 65534 is usually user 'nobody'.
 # The executor of this image should still specify a user during setup.
 COPY --chown=65534:0 --from=builder /data /data
 USER 65534
 WORKDIR /data
 
 ENTRYPOINT ["/orionadapter"]
-CMD [ "43210" ]
-EXPOSE 43210
+CMD [ "43210", "54321" ]
+EXPOSE 43210 54321

deployment/egress_filter.yaml

@@ -0,0 +1,52 @@
+apiVersion: networking.istio.io/v1alpha3
+kind: EnvoyFilter
+metadata:
+  name: orion-egress-filter
+  namespace: default
+spec:
+  workloadSelector:
+    labels:
+      app: httpbin
+  configPatches:
+  # The first patch adds the lua filter to the listener/http connection manager
+  - applyTo: HTTP_FILTER
+    match:
+      context: SIDECAR_OUTBOUND
+      listener:
+        portNumber: 80
+        filterChain:
+          filter:
+            name: "envoy.http_connection_manager"
+            subFilter:
+              name: "envoy.router"
+    patch:
+      operation: INSERT_BEFORE
+      value: # lua filter specification
+        name: envoy.lua
+        config:
+          inlineCode: |
+            function envoy_on_request(request_handle)
+              local headers, body = request_handle:httpCall(
+                    "lua_cluster", {
+                          [":method"] = "GET",
+                          [":path"] = "/",
+                          [":authority"] = "lua_cluster"}, "", 5000)
+              request_handle:headers():add("header", body)
+            end
+  # The second patch adds the cluster that is referenced by the lua code
+  # cds match is omitted as a new cluster is being added
+  - applyTo: CLUSTER
+    # match:
+    #   context: SIDECAR_OUTBOUND
+    patch:
+      operation: ADD
+      value: # cluster specification
+        name: "lua_cluster"
+        type: STRICT_DNS
+        connect_timeout: 5.5s
+        lb_policy: ROUND_ROBIN
+        hosts:
+        - socket_address:
+            protocol: TCP
+            address: "orionadapterservice.istio-system"
+            port_value: 54321

deployment/orion_adapter_service.yaml

@@ -12,6 +12,10 @@ spec:
     protocol: TCP
     port: 43210
     targetPort: 43210
+  - name: http
+    protocol: TCP
+    port: 54321
+    targetPort: 54321
   selector:
     app: orionadapter
 ---
@@ -41,3 +45,6 @@ spec:
         imagePullPolicy: Never
         ports:
         - containerPort: 43210
+          name: grpc
+        - containerPort: 54321
+          name: http

orionadapter/main.go

@@ -2,6 +2,8 @@ package main
 
 import (
 	"fmt"
+	"log"
+	"net/http"
 	"os"
 	"strconv"
 
@@ -20,6 +22,9 @@ func main() {
 	go func() {
 		s.Run(shutdown)
 	}()
+
+	runHTTP()
+
 	_ = <-shutdown
 }
 
@@ -31,3 +36,21 @@ func readPortArg() int {
 	}
 	return 0
 }
+
+// TODO: refactor this mess!!
+
+func token(w http.ResponseWriter, req *http.Request) {
+	fmt.Fprintf(w, "whoopsie.dapsie!!")
+}
+
+func runHTTPServerLoop(port string) {
+	http.HandleFunc("/", token)
+	addr := fmt.Sprintf(":%s", port)
+
+	log.Fatal(http.ListenAndServe(addr, nil))
+}
+
+func runHTTP() {
+	port := os.Args[2] // TODO let it bomb out if no arg?!
+	go runHTTPServerLoop(port)
+}