base dockerfile: add tini, entrypoint that calls /app/entrypoint.sh

base/Dockerfile

@@ -1,9 +1,28 @@
 # Not using -slim, as Axel can't figure out where to get packages there.
 FROM python:2.7.14-stretch
 
+ENV TINI_VERSION v0.17.0
+RUN set -x && \
+    curl -Lo /tini "https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini" && \
+    curl -Lo /tmp/tini.asc "https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini.asc" && \
+    export GNUPGHOME="$(mktemp -d)" && \
+    for server in $(shuf -e ha.pool.sks-keyservers.net \
+                            hkp://p80.pool.sks-keyservers.net:80 \
+                            keyserver.ubuntu.com \
+                            hkp://keyserver.ubuntu.com:80 \
+                            pgp.mit.edu) ; do \
+        gpg --keyserver "$server" --recv-keys 595E85A6B1B4779EA4DAAEC70B588DFF0527A9B7 && break || : ; \
+    done && \
+    gpg --batch --verify /tmp/tini.asc /tini && \
+    rm -r "$GNUPGHOME" /tmp/tini.asc && \
+    chmod +x /tini
+
 WORKDIR /app/
 RUN groupadd --gid 10001 app && useradd -g app --uid 10001 --shell /usr/sbin/nologin app
 
 # Install OS-level things
 COPY ./base/set_up.sh /tmp/
 RUN DEBIAN_FRONTEND=noninteractive /tmp/set_up.sh
+
+ENTRYPOINT ["/tini", "--"]
+CMD ["/app/entrypoint.sh"]