...
heroku config:set --app scihist-digicoll-production LOGINS_DISABLED=true APP_URL_BASE=https://digital.sciencehistory.org
DNS
point Remove the A record for digital.sciencehistory.org
Point the CNAME for digital.sciencehistory.org to peaceful-basilisk-lhtznpb53fvrt1mv8yt398yy.herokudns.com
point Remove the A record for staging-digital.sciencehistory.org
Point the CNAME for staging-digital.sciencehistory.org to convex-pelican-rsz77g7eof8bvxziiakaer03.herokudns.com
point Point the CNAME for oh.sciencehistory.org to tranquil-gibbon-icqi7z9ngvnj4toc8g4ialyl.herokudns.comsd
...
Switch back
Switch DNS back,
Remove CNAME for digital.sciencehistory.org
Point the A record for digital.sciencehistory.org to 54.173.133.90
Remove CNAME for staging-digital.sciencehistory.org
Point the A record for staging-digital.sciencehistory.org to 52.7.156.95
Point the CNAME for oh.sciencehistory.org to digital.sciencehistory.org
then:heroku config:set --app scihist-digicoll-production LOGINS_DISABLED=false APP_URL_BASE=https://scihist-digicoll-production.herokuapp.com