fpm alpine mysql,错误：约束无法满足-在php：7-fpm-alpine上

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?

解决方案

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/*