Initial cloud-services repo - gateway service + pkg modules

pkg/tracer/README.md

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+# Tracing with DataDog
+
+Run DataDog agent locally (make sure to replace `DD_API_KEY`):
+```
+docker run --name dd-agent -e DD_APM_ENABLED=true -v /var/run/docker.sock:/var/run/docker.sock:ro -v /proc/:/host/proc/:ro -v /sys/fs/cgroup/:/host/sys/fs/cgroup:ro --net="host" -e DD_API_KEY=<DD_API_KEY> gcr.io/datadoghq/agent:7
+```
+
+Connect the docker container to the network:
+```
+docker run --rm --net="host" order
+``

pkg/tracer/tracer.go

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+package tracer
+
+import (
+	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
+
+	"fiskerinc.com/modules/utils/envtool"
+)
+
+var agentAvailable bool
+
+func Start() {
+	agentAvailable = envtool.GetEnv("DD_AGENT_HOST", "") != ""
+	if agentAvailable {
+		tracer.Start()
+	}
+}
+
+func Stop() {
+	if agentAvailable {
+		tracer.Stop()
+	}
+}