Use alpine 3.10 for cross compilation support and consistency of pyth…

…on 3.7 version between multiarch x86_64 and armv7

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.11 as py-ea
+FROM alpine:3.10 as py-ea
 ARG ELASTALERT_VERSION=1334b611fdd7adf39991a1b0b11689568d612690
 ENV ELASTALERT_VERSION=${ELASTALERT_VERSION}
 # URL from which to download Elastalert.
@@ -9,7 +9,7 @@ ENV ELASTALERT_HOME /opt/elastalert
 
 WORKDIR /opt
 
-RUN apk add --update --no-cache ca-certificates openssl-dev openssl python3-dev==3.8.2-r0 python3==3.8.2-r0 py3-pip py3-yaml libffi-dev gcc musl-dev wget && \
+RUN apk add --update --no-cache ca-certificates openssl-dev openssl python3-dev==3.7.5-r1 python3==3.7.5-r1 py3-pip py3-yaml libffi-dev gcc musl-dev wget && \
 # Download and unpack Elastalert.
     wget -O elastalert.zip "${ELASTALERT_URL}" && \
     unzip elastalert.zip && \
@@ -27,9 +27,9 @@ LABEL maintainer="John Belisle <[email protected]>"
 # Set timezone for this container
 ENV TZ America/New_York
 
-RUN apk add --update --no-cache curl tzdata python3==3.8.2-r0 make libmagic && \
+RUN apk add --update --no-cache curl tzdata python3==3.7.5-r1 make libmagic && \
     ln -s /usr/bin/python3 /usr/bin/python
-COPY --from=py-ea /usr/lib/python3.8/site-packages /usr/lib/python3.8/site-packages
+COPY --from=py-ea /usr/lib/python3.7/site-packages /usr/lib/python3.7/site-packages
 COPY --from=py-ea /opt/elastalert /opt/elastalert
 COPY --from=py-ea /usr/bin/elastalert* /usr/bin/