ERROR: unsatisfiable constraints - on php:7-fpm-alpine

Question

I'm looking at setting up laravel on an fpm-alpine container. Running into a snag where the below Dockerfile is producing some errors...

FROM php:7-fpm-alpine

# install extensions needed for Laravel
RUN apk --update add \
  php7-mysqli \
  php7-mcrypt \
  php7-mbstring \
  rm /var/cache/apk/*

Errors produced are:

Building fpm
Step 1 : FROM php:7-fpm-alpine
 ---> 9e6811cb8bac
Step 2 : RUN apk --update add   php7-mysqli   php7-mcrypt   php7-mbstring   rm /var/cache/apk/*
 ---> Running in 87364957eb57
fetch http://dl-cdn.alpinelinux.org/alpine/v3.3/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.3/community/x86_64/APKINDEX.tar.gz
ERROR: unsatisfiable constraints:
  /var/cache/apk/* (missing):
    required by: world[/var/cache/apk/*]
  php7-mbstring (missing):
    required by: world[php7-mbstring]
  php7-mcrypt (missing):
    required by: world[php7-mcrypt]
  php7-mysqli (missing):
    required by: world[php7-mysqli]
  rm (missing):
    required by: world[rm]
ERROR: Service 'fpm' failed to build: The command '/bin/sh -c apk --update add   php7-mysqli   php7-mcrypt   php7-mbstring   rm /var/cache/apk/*' returned a non-zero code: 5

I can search for these package names and find them on the alpine linux web site. Any thoughts on how I can work around this? It's like it's not updating the apt cache... but adding an LS I can see contents there:

Building fpm
Step 1 : FROM php:7-fpm-alpine
 ---> 9e6811cb8bac
Step 2 : RUN apk update
 ---> Using cache
 ---> 9ef09f3aa2a2
Step 3 : RUN ls /var/cache/apk
 ---> Running in e126a083a306
APKINDEX.5a59b88b.tar.gz
APKINDEX.7c1f02d6.tar.gz

Any ideas on what I can do to resolve this?

Answer 1

Base Docker image probably references an incorrect repository.

Pass over the correct repositories to the apk add command like this:

RUN apk add --update \
--repository http://dl-cdn.alpinelinux.org/alpine/edge/main \
--repository http://dl-cdn.alpinelinux.org/alpine/edge/community \
php7-mysqli php7-mcrypt php7-mbstring

Answer 2

I wasn't using docker-php-ext-install which is required when adding working within the container...

FROM php:7-fpm-alpine

# install extensions needed for Laravel
RUN apk update \
    && apk add libmcrypt-dev \
    && docker-php-ext-install mcrypt mysqli pdo_mysql \
    && rm /var/cache/apk/*

Answer 3

I met the same error. Solved it by removing the package version from its name:

https://github.com/docker-library/php/issues/225#issuecomment-220339154