Shrinkin image size

Signed-off-by: Damien DUPORTAL <damien.duportal@gmail.com>

Dockerfile

@@ -1,13 +1,37 @@
 FROM ubuntu:16.04
-MAINTAINER Shuanglei Tao "tsl0922@gmail.com"
+LABEL maintainer "Shuanglei Tao - tsl0922@gmail.com"
 
-RUN apt-get update && \
-    apt-get install -y cmake g++ pkg-config git vim-common libwebsockets-dev libjson-c-dev libssl-dev && \
-    rm -rf /var/lib/apt/lists/* && \
-    git clone --depth=1 https://github.com/tsl0922/ttyd.git /tmp/ttyd && \
-    cd /tmp/ttyd && mkdir build && cd build && \
-    cmake .. && make && make install && \
-    rm -rf /tmp/ttyd
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends \
+      ca-certificates \
+      cmake \
+      curl \
+      g++ \
+      git \
+      libjson-c2 \
+      libjson-c-dev \
+      libssl1.0.0 \
+      libssl-dev \
+      libwebsockets7 \
+      libwebsockets-dev \
+      pkg-config \
+      vim-common \
+    && git clone --depth=1 https://github.com/tsl0922/ttyd.git /tmp/ttyd \
+    && cd /tmp/ttyd && mkdir build && cd build \
+    && cmake .. \
+    && make \
+    && make install \
+    && apt-get remove -y --purge \
+        cmake \
+        g++ \
+        libwebsockets-dev \
+        libjson-c-dev \
+        libssl-dev \
+        pkg-config \
+    && apt-get purge -y \
+    && apt-get autoremove -y \
+    && rm -rf /var/lib/apt/lists/* \
+    && rm -rf /tmp/ttyd
 
 EXPOSE 7681