loadgenerator: Reduced docker image size to ~117MB (down from ~972MB). Changed to a multi stage build and switched to using python:3-alpine as base image

src/loadgenerator/Dockerfile

@@ -1,7 +1,21 @@
-FROM python:3.6
+FROM python:3-alpine as base
+
+FROM base as builder
+
+RUN apk add --update --no-cache \
+    gcc \
+    linux-headers \
+    make \
+    musl-dev \
+    python-dev \
+    g++
 
 COPY requirements.txt .
-RUN pip install -r requirements.txt
+
+RUN pip install --install-option="--prefix=/install" -r requirements.txt
+
+FROM base
+COPY --from=builder /install /usr/local
 
 COPY . .
 ENTRYPOINT ./loadgen.sh