merge mode

Merge (ONBUILD) mode usage

First import your extensions:

FROM wyga/php-ext-intl:7.4
FROM wyga/php-ext-imap:7.4
FROM wyga/php-ext-mcrypt:7.4
FROM wyga/php-ext-memcached:7.4
FROM wyga/php-ext-pgsql:7.4
FROM wyga/php-ext-zip:7.4

Count number of FROM's. In this example we have 6. Merge previous imports with wyga/merge.
Put 6 as a tag (number of previous imports) and put merge as stage name (important!).

FROM wyga/merge:6 AS merge

Lastly add wyga/php-merge

FROM wyga/php-merge:7.4

And build your image.

Above example is equivalent to this:

FROM wyga/php-ext-intl:7.4
FROM wyga/php-ext-imap:7.4
FROM wyga/php-ext-mcrypt:7.4
FROM wyga/php-ext-memcached:7.4
FROM wyga/php-ext-pgsql:7.4
FROM wyga/php-ext-zip:7.4

FROM wyga/php:7.4
COPY --from=0 / / 
COPY --from=1 / / 
COPY --from=2 / / 
COPY --from=3 / / 
COPY --from=4 / / 
COPY --from=5 / / 
RUN wyga-php-setup