dockerfile: Upgrate base image to ubuntu:18.04

Signed-off-by: Radostin Stoyanov <[email protected]>

Author: rst0git

Dockerfile

@@ -1,15 +1,15 @@
-FROM ubuntu:16.04 as builder
+FROM ubuntu:18.04 as builder
 RUN apt-get update
 RUN \
   DEBIAN_FRONTEND=noninteractive \
   apt-get install -y \
     build-essential autoconf automake libpcre3-dev libevent-dev \
-    pkg-config zlib1g-dev git libboost-all-dev cmake flex
+    pkg-config zlib1g-dev git libboost-all-dev cmake flex libssl-dev
 RUN git clone https://github.com/RedisLabs/memtier_benchmark.git
 WORKDIR /memtier_benchmark
 RUN autoreconf -ivf && ./configure && make && make install
 
-FROM ubuntu:16.04
+FROM ubuntu:18.04
 LABEL Description="memtier_benchmark"
 COPY --from=builder /usr/local/bin/memtier_benchmark /usr/local/bin/memtier_benchmark
 RUN \