ERROR: unsatisfiable constraints: so:libvpx.so.6 (missing) - ffmpeg

Question

FFMpeg was updated this week and is causing the build to break.
Are my options to either:
pin ffmpeg to a previous version? If so, how do I pin to the version before current?
Update the python dockerfile version
Output:
Step 8/42 : RUN apk add --no-cache ffmpeg
---> Running in 9e46540ed393
fetch http://dl-cdn.alpinelinux.org/alpine/v3.8/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.8/community/x86_64/APKINDEX.tar.gz
fetch http://dl-8.alpinelinux.org/alpine/edge/community/x86_64/APKINDEX.tar.gz
ERROR: unsatisfiable constraints:
so:libvpx.so.6 (missing):
required by:
ffmpeg-libs-4.1.1-r2[so:libvpx.so.6]
ffmpeg-libs-4.1.1-r2[so:libvpx.so.6]
ffmpeg-libs-4.1.1-r2[so:libvpx.so.6]
ffmpeg-libs-4.1.1-r2[so:libvpx.so.6]
ffmpeg-libs-4.1.1-r2[so:libvpx.so.6]
ffmpeg-libs-4.1.1-r2[so:libvpx.so.6]
ffmpeg-libs-4.1.1-r2[so:libvpx.so.6]
ffmpeg-libs-4.1.1-r2[so:libvpx.so.6]
ffmpeg-libs-4.1.1-r2[so:libvpx.so.6]
ffmpeg-libs-4.1.1-r2[so:libvpx.so.6]
The command '/bin/sh -c apk add --no-cache ffmpeg' returned a non-zero code: 3
ERROR: Job failed: exit code 3
FATAL: exit code 3
Dockerfile:
FROM python:3.6.7-alpine
ENV LANG C.UTF-8
RUN echo "http://dl-8.alpinelinux.org/alpine/edge/community" >> /etc/apk/repositories
RUN apk upgrade
RUN addgroup -S django && adduser -S -G django django
RUN apk update
# FFMPEG/Sox dependencies
RUN apk add sox
#RUN apk add --no-cache libvpx-dev
RUN apk add --no-cache ffmpeg

Answer 1

You are only adding the community edge repository, not main. This leads to some inconsistencies for apk.
It works if you change your Dockerfile:4 to the following:
RUN echo -e "http://dl-cdn.alpinelinux.org/alpine/edge/community\nhttp://dl-cdn.alpinelinux.org/alpine/edge/main" >> /etc/apk/repositories