Add alpine pkg "tzdata" to alpine Dockerfile template

[seagleNet]

With the package "tzdata" installed on the alpine image it's easily possible to set the container's timezone by setting TZ environment variable (e.g. TZ=Europe/Zurich).

[tianon]

It's a fairly small amount of added space, but I'm not convinced it's relevant for us to add -- many users likely don't care about timezone data (and even though small, it becomes unremovable if we add it here), and for the rest, bind-mounting /etc/localtime from the host into the container (instead of setting TZ) will usually just do-the-expected-thing for users (setting the container's timezone to that of the host).

[J0WI]

The Debian variant has it by default.

[phy25]

The Debian variant has it by default.

debian's tzdata is installed by upstream, not by this Dockerfile, while alpine is as clean as possible by default.

$ docker run -it --rm debian apt list --installed | grep tzdata
tzdata/now 2019c-0+deb10u1 all [installed,local]

I think debian and alpine varients have different directions towards what to have/what not to have. As @tianon mentioned, the size of the image will increase once tzdata is installed, which cannot be avoided by end users, and I believe a lot of users are not expecting this.

[tianon]

Indeed, in my mind the main difference is that the Alpine variants are all explicitly focused on minimal size (it's the main compelling argument to using Alpine in the first place).

[seagleNet]

While I agree about Alpine's main appeal being the minimal size, but we're talking about 3MB here. Is that really that big of a deal?

Also from what I've learned it should be avoided as much as possible mounting volumes/files into your container and instead use environment variables where possible.

I saw that nginx installs tzdata by default in their Alpine image:
https://github.com/nginxinc/docker-nginx/blob/master/mainline/alpine/Dockerfile#L101

[phy25]

Some references:

nginxinc/docker-nginx#149
redis/docker-library-redis#138

[thaJeztah]

Alpine is really fast when installing packages, so adding it to either your Dockerfile (add a RUN apk add --no-cache tzdata) or even at runtime (if you don't use a Dockerfile 🙀) would allow you to add the package if you need it;

Looks like it takes less than a second to install;

docker run --rm php:alpine sh -c 'time apk add --no-cache tzdata && exec php -a'

fetch http://dl-cdn.alpinelinux.org/alpine/v3.11/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.11/community/x86_64/APKINDEX.tar.gz
(1/1) Installing tzdata (2019c-r0)
Executing busybox-1.31.1-r9.trigger
OK: 23 MiB in 33 packages
real	0m 0.53s
user	0m 0.09s
sys	0m 0.06s
Interactive shell

[phy25]

Honestly if every image adds tzdata, 2MB will become a lot. I am not sure if this should be a baseline of alpine or something else - Apache here I believe only uses it for logging as Redis does.

[tianon]

I think docker-library/golang#250 (comment) is pretty relevant here also.

[mvorisek]

are tzdata used actually by php?

[tianon]

I don't think so -- without adding tzdata, I'm able to still use date/time related functions, and they work appropriately when I change the timezone:

$ docker pull php:alpine
alpine: Pulling from library/php
Digest: sha256:edd37734c824c65cdbc1e68c9ac928c590a5c750b6b49c656a302b3b0742d371
Status: Image is up to date for php:alpine
docker.io/library/php:alpine

$ docker run -it --rm php:alpine
Interactive shell

php > echo date(DATE_RFC2822);
Thu, 01 Jul 2021 18:39:48 +0000
php > date_default_timezone_set('America/Los_Angeles');
php > echo date(DATE_RFC2822);
Thu, 01 Jul 2021 11:40:02 -0700

[mvorisek]

I think this should be closed then as it is completely unrelated to php.