Update to alpine 3.15

[BlackthornYugen]

There are many security updates we are missing out on (including zlib CVE-2018-25032) by using the EOL alpine 3.11. This change updates to Alpine 3.15.

[tianon]

I did a build test of this via docker build --pull https://github.com/BlackthornYugen/mongo-express-docker.git#patch-1 and it builds fine -- I'm not comfortable merging many things here (as I'm not a maintainer of either this project or mongo-express), but this one seems sane/safe IMO (so I'm going for it). :sweat_smile:

[tianon]

Ah, but we're back to the core problem of #62 -- node:12* is not supported :disappointed:

(https://hub.docker.com/_/node)

[BlackthornYugen]

@tianon I'm confused, is this merge okay? or does it break something? It's still node 12 right? I just did a fresh build and I'm showing it's on node12:

bash-5.1# node --version
v12.22.12

bash-5.1# cat /etc/*rel*
3.15.4
NAME="Alpine Linux"
ID=alpine
VERSION_ID=3.15.4
PRETTY_NAME="Alpine Linux v3.15"
HOME_URL="https://alpinelinux.org/"
BUG_REPORT_URL="https://bugs.alpinelinux.org/"

bash-5.1# apk policy zlib
WARNING: Ignoring https://dl-cdn.alpinelinux.org/alpine/v3.15/main: No such file or directory
WARNING: Ignoring https://dl-cdn.alpinelinux.org/alpine/v3.15/community: No such file or directory
zlib policy:
  1.2.12-r0:
    lib/apk/db/installed

[BlackthornYugen]

Are you saying not all versions of node 12 are supported?

[tianon]

Sorry for not being clear -- I'm saying that due to https://github.com/nodejs/docker-node/pull/1701, this is problematic. The node:12-alpine3.15 image is reasonably recent, but it will not be updated any further beyond what's currently published.

[BlackthornYugen]

Right -- I can take a shot at migrating to a more recent node version sometime in the next couple months if nobody else is able to get to it.