docker - example adding www-data user to alpine images

Dockerfile.fails

FROM nginx:alpine

# stock verison from php:alpine image

# ensure www-data user exists
RUN set -x \
	&& addgroup -g 82 -S www-data \
	&& adduser -u 82 -D -S -G www-data www-data
# 82 is the standard uid/gid for "www-data" in Alpine
# http://git.alpinelinux.org/cgit/aports/tree/main/apache2/apache2.pre-install?h=v3.3.2
# http://git.alpinelinux.org/cgit/aports/tree/main/lighttpd/lighttpd.pre-install?h=v3.3.2
# http://git.alpinelinux.org/cgit/aports/tree/main/nginx-initscripts/nginx-initscripts.pre-install?h=v3.3.2

Dockerfile.works

FROM nginx:alpine

# modified version from php:alpine image

# ensure www-data user exists
RUN set -x ; \
  addgroup -g 82 -S www-data ; \
  adduser -u 82 -D -S -G www-data www-data && exit 0 ; exit 1
# 82 is the standard uid/gid for "www-data" in Alpine
# http://git.alpinelinux.org/cgit/aports/tree/main/apache2/apache2.pre-install?h=v3.3.2
# http://git.alpinelinux.org/cgit/aports/tree/main/lighttpd/lighttpd.pre-install?h=v3.3.2
# http://git.alpinelinux.org/cgit/aports/tree/main/nginx-initscripts/nginx-initscripts.pre-install?h=v3.3.2