Reliable CDN mirror for debian?

Since switching from debian:jessie to debian:stretch as the base image of my Dockerfiles, I've experienced a remarkably high frequency of 503 errors on apt-get commands using the image's default URL for the stretch repos, deb http://deb.debian.org/debian stretch main which I understand is Debian's official CDN. Usually these are resolved by rebuilding the instances at some later time, but are still a nuisance. Perhaps these issues are due to stretch only recently being released as stable, but into today's world of easily available high performance content delivery networks this seems surprising. Are there alternative CDN-based mirrors for debian that would be faster / more reliable? Are there AWS-S3 backed mirrors for debian sources? (Not really looking for a regional mirror since the containers could be built anywhere). Example 503 error messages: Get:220 http://deb.debian.org/debian stretch/main amd64 vim-runtime all 2:8.0.0197-4 [5,409 kB] Get:221 http://deb.debian.org/debian stretch/main amd64 vim amd64 2:8.0.0197-4 [1,033 kB] Fetched 201 MB in 5min 4s (660 kB/s) [91mE: Failed to fetch http://deb.debian.org/debian/pool/main/g/ghostscript/ghostscript_9.20~dfsg-3.2_amd64.deb 503 Service Temporarily Unavailable [IP: 13.32.244.252 80] E: Failed to fetch http://deb.debian.org/debian/pool/main/h/harfbuzz/libharfbuzz-icu0_1.4.2-1_amd64.deb 503 Service Temporarily Unavailable [IP: 13.32.244.252 80] E: Failed to fetch http://deb.debian.org/debian/pool/main/h/hunspell/libhunspell-1.4-0_1.4.1-2+b2_amd64.deb 503 Service Temporarily Unavailable [IP: 13.32.244.252 80] E: Failed to fetch http://deb.debian.org/debian/pool/main/h/hunspell/libhunspell-dev_1.4.1-2+b2_amd64.deb 503 Service Temporarily Unavailable [IP: 13.32.244.252 80] E: Failed to fetch http://deb.debian.org/debian/pool/main/p/potrace/libpotrace0_1.13-3_amd64.deb 503 Service Temporarily Unavailable [IP: 13.32.244.252 80] E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing? Alternately, is there a better way to run apt to retry or be more patient about these 503 errors?