use different base image and include ssm plugin

.gitignore

@@ -0,0 +1 @@
+.idea

Dockerfile

@@ -1,28 +1,24 @@
-FROM hashicorp/terraform:0.12.20
+FROM ubuntu:18.04
 
-RUN apk add --update --no-cache \
-    bash \
-    make \
-    g++ \
-    git \
-    openssl \
-    openssl-dev \
-    curl
+ARG DEBIAN_FRONTEND=noninteractive
+
+RUN apt-get update
+RUN apt-get install -y \
+    curl \
+    unzip \
+    git-crypt \
+    awscli
 
 # install tflint
-RUN curl -L -o /tmp/tflint.zip https://github.com/terraform-linters/tflint/releases/download/v0.14.0/tflint_linux_amd64.zip 
+RUN curl -L -o /tmp/tflint.zip https://github.com/terraform-linters/tflint/releases/download/v0.14.0/tflint_linux_amd64.zip
 RUN echo "4908d30078ecbd3b732ce5c2caabad77b6b768d46397ae009dd8dab8a1cbf6ac  /tmp/tflint.zip" | sha256sum -c
 RUN unzip /tmp/tflint.zip -d /usr/local/bin
 
-# install git-crypt
-RUN curl -L -o /tmp/git-crypt.tar.gz 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 && make && make install PREFIX=/usr/local
+RUN curl -O https://releases.hashicorp.com/terraform/0.12.20/terraform_0.12.20_linux_amd64.zip
+RUN unzip terraform_0.12.20_linux_amd64.zip
+RUN mv terraform /usr/local/bin/
 
-RUN apk -Uuv add groff less python py-pip
-RUN pip install awscli
-RUN apk --purge -v del py-pip
-RUN rm /var/cache/apk/*
+RUN curl "https://s3.amazonaws.com/session-manager-downloads/plugin/latest/ubuntu_64bit/session-manager-plugin.deb" -o "session-manager-plugin.deb"
+RUN dpkg -i session-manager-plugin.deb