nextcloud-docs/perl/content.md

What is Perl?

Perl is a high-level, general-purpose, interpreted, dynamic programming language. The Perl language borrows features from other programming languages, including C, shell scripting (sh), AWK, and sed.

wikipedia.org/wiki/Perl

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How to use this image

Create a Dockerfile in your Perl app project

FROM %%IMAGE%%:5.20
COPY . /usr/src/myapp
WORKDIR /usr/src/myapp
CMD [ "perl", "./your-daemon-or-script.pl" ]

Then, build and run the Docker image:

$ docker build -t my-perl-app .
$ docker run -it --rm --name my-running-app my-perl-app

Run a single Perl script

For many simple, single file projects, you may find it inconvenient to write a complete Dockerfile. In such cases, you can run a Perl script by using the Perl Docker image directly:

$ docker run -it --rm --name my-running-script -v "$PWD":/usr/src/myapp -w /usr/src/myapp %%IMAGE%%:5.20 perl your-daemon-or-script.pl

Example: Creating a reusable Carton image for Perl projects

Suppose you have a project that uses Carton to manage Perl dependencies. You can create a %%IMAGE%%:carton image that makes use of the ONBUILD instruction in its Dockerfile, like this:

FROM %%IMAGE%%:5.26

RUN cpanm Carton \
    && mkdir -p /usr/src/app
WORKDIR /usr/src/app

ONBUILD COPY cpanfile* /usr/src/myapp
ONBUILD RUN carton install

ONBUILD COPY . /usr/src/app

Then, in your Carton project, you can now reduce your project's Dockerfile into a single line of FROM %%IMAGE%%:carton, which may be enough to build a stand-alone image.

Having a single %%IMAGE%%:carton base image is useful especially if you have multiple Carton-based projects in development, to avoid "boilerplate" coding of installing Carton and/or copying the project source files into the derived image. Keep in mind, though, about certain things to consider when using the Perl image in this way:

• This kind of base image will hide the useful bits (such as theCOPY/RUN above) in the image, separating it from more specific Dockerfiles using the base image. This might lead to confusion when creating further derived images, so be aware of how ONBUILD triggers work and plan appropriately.
• There is the cost of maintaining an extra base image build, so if you're working on a single Carton project and/or plan to publish it, then it may be more preferable to derive directly from a versioned perl image instead.