Add git-crypt to docker

Dockerfile

@@ -1,7 +1,19 @@
 FROM hashicorp/terraform:0.11.13
 
-RUN apk add --update --no-cache make bash
-# install tflint
+RUN apk add --update --no-cache \
+    bash \
+    make \
+    g++ \
+    git \
+    openssl \
+    openssl-dev 
 
+# install tflint
 RUN curl -L -o /tmp/tflint.zip https://github.com/wata727/tflint/releases/download/v0.6.0/tflint_linux_amd64.zip && unzip /tmp/tflint.zip -d /usr/local/bin
 RUN echo "4a8cfd03001c79cb9f4a85c8e195fff1a676656467acbc5d078d516df809f31a  /usr/local/bin/tflint" | sha256sum -c
+
+# install git-crypt
+RUN curl -L -o /tmp/git-crypt.zip https://www.agwa.name/projects/git-crypt/downloads/git-crypt-0.6.0.tar.gz
+RUN echo "6d30fcd99442d50f4b3c8d554067ff1d980cdf9f3120ee774131172dba98fd6f  /tmp/git-crypt.tar.gz" | sha256sum -c
+RUN tar -zxf /tmp/git-crypt.tar.gz
+RUN cd git-crypt-0.6.0.tar.gz && make && make install PREFIX=/usr/local