# elixir-pdf-generator

A wrapper for both wkhtmltopdf and chrome-headless plus PDFTK (adds in
encryption) for use in Elixir projects.

# Latest release v0.6.0 on 2019-12-17

- 0.6.0
  - introducting `make` as build tool (optional) for chromium binaries
  - **BUGFIX:** documentation: option `pagesize` requires string argument
    (for example `"letter"` or `"A4"`)
  - updated some npm dependencies for chromium

For a proper changelog, see [CHANGES](

# Usage

_Hint:_ In IEX, `h PdfGenerator.generate` is your friend.

Add this to your dependencies in your mix.exs:

    def application do
        [applications: [
            :pdf_generator # <-- add this for Elixir <= 1.4

    defp deps do
            # ... whatever else
            { :pdf_generator, ">=0.6.0" }, # <-- and this

If you want to use a locally-installed chromium in **RELEASES** (think `mix
release`), alter your mixfile to let make take care of comilation and

defp deps do
    # ... whatever else
    { :pdf_generator, ">=0.6.0", compile: "make chrome" }

This will embed a **300 MB** (yes, that large) Chromium binary into your priv folder
which will survive packaging as Erlang release. This _can_ be handy as this will
run on slim Alpine docker images with just NodeJS installed.

The recommended way still is to install Chromium/Puppeteer globally and set the
`prefer_system_executable: true` option when generating PDFs.

In development: While this usually works, it unfortunately leads to
pdf_generator to be compiled all the time again and again due to my bad Makefile
skills. Help is very much appreciated.

## Try it out

Then pass some html to PdfGenerator.generate

$ iex -S mix

html = "<html><body><p>Hi there!</p></body></html>"
# be aware, this may take a while...
{:ok, filename}    = PdfGenerator.generate(html, page_size: "A5")
{:ok, pdf_content} =

# or, if you prefer methods that raise on error:
filename = PdfGenerator.generate!(html, generator: :chrome)

Or, pass some URL

PdfGenerator.generate {:url, ""}, page_size: "A5"

Or, use **chrome-headless** – if you're (most probably) using this as
dependency, chrome won't be installed to this project directory but globally. We
currently need to tell PdfGenerator this by setting the
`prefer_system_executable: true` option. This will be default by v0.6.0.

html_works_too = "<html><body><h1>Minimalism!"
{:ok, filename} = PdfGenerator.generate html_works_too, generator: :chrome, prefer_system_executable: true

If using chrome in a superuser/root environment (read: **docker**), make sure to
pass an option to chrome to disable sandboxing. And be aware of the implications.

html_works_too = "<html><body><h1>I need Docker, baby docker is what I need!"
{:ok, filename} = PdfGenerator.generate html_works_too, generator: :chrome, no_sandbox: true, page_size: "letter"

Or use the bang-methods:

filename   = PdfGenerator.generate! "<html>..."
pdf_binary = PdfGenerator.generate_binary! "<html>..."

# System prerequisites 

It's either 

* wkhtmltopdf or 

* nodejs (for chromium/puppeteer)

## chrome-headless

This will allow you to make more use of Javascript and advanced CSS as it's just
your Chrome/Chromium browser rendering your web page as HTML and printing it as
PDF. Rendering _tend_ to be a bit faster than with wkhtmltopdf. The price tag is
that PDFs printed with chrome/chromium are usually considerably bigger than
those generated with wkhtmltopdf.

### global install (great for Docker images)

Run `npm -g install chrome-headless-render-pdf puppeteer`. 

This requires [nodejs](, of course. This will install a
recent chromium and chromedriver to run Chrome in headless mode and use this
browser and its API to print PDFs globally on your machine.
If you prefer a project-local install, just use `npm install` This will install
dependencies under `./node_modules`. Be aware that those won't be packaged in
your distribution (I will add support for this later).

On some machines, this doesn't install Chromium and fails. Here's how to get
this running on Ubuntu 18:
  apt-get install -y chromium-chromedriver \
  && npm -g install chrome-headless-render-pdf puppeteer

### local install

Run `make priv/node_modules`. This requires both `nodejs` (insallation see
above) and `make`. 

Or, run `cd priv && npm install`
## wkhtmltopdf

2. Download wkhtmltopdf and place it in your $PATH. Current binaries can be
   found here:
   For the impatient (Ubuntu 18.04 Bionic Beaver):
   apt-get -y install xfonts-base xfonts-75dpi \
    && wget \
    && dpkg -i wkhtmltox_0.12.5-1.bionic_amd64.deb
   For other distributions, refer to – For
   example, replace `bionic` with `xenial` if you're on Ubuntu 16.04.
## optional dependencies

3. _optional:_ Install `xvfb` (shouldn't be required with the binary mentioned above):

   To use other wkhtmltopdf executables comiled with an unpatched Qt on systems
   without an X window server installed, please install `xvfb-run` from your
   repository (on Debian/Ubuntu: `sudo apt-get install xvfb`).
   I haven't heard any feedback of people using this feature since a while since
   the wkhtmltopdf projects ships ready-made binaries. I will deprecate this
   starting in `0.6.0` since, well, YAGNI.

4. _optional:_ Install `pdftk` via your package manager or homebrew. The project
   page also contains a Windows installer. On Debian/Ubuntu just type:
   `apt-get -y install pdftk`

# Options and Configuration

This module will automatically try to finde both `wkhtmltopdf` and `pdftk` in
your path. But you may override or explicitly set their paths in your

config :pdf_generator,
    wkhtml_path:    "/usr/bin/wkhtmltopdf",   # <-- this program actually does the heavy lifting
    pdftk_path:     "/usr/bin/pdftk"          # <-- only needed for PDF encryption

or, if you prefer chrome-headless

config :pdf_generator,
    use_chrome: true,                           # <-- make sure you installed node/puppeteer
    prefer_system_executable: true              # <-- set this if you installed the NPM dependencies globally
    raise_on_missing_wkhtmltopdf_binary: false, # <-- so the app won't complain about a missing wkhtmltopdf

## More options

- `filename` - filename for the output pdf file (without .pdf extension, defaults to a random string)

- `page_size`:
  *  defaults to `"A4"`, see `wkhtmltopdf` for more options
  * `"letter"` (for US letter) be translated to 8x11.5 inches (currently, only in chrome).

- `open_password`:    requires `pdftk`, set password to encrypt PDFs with

- `edit_password`:    requires `pdftk`, set password for edit permissions on PDF

- `shell_params`:     pass custom parameters to `wkhtmltopdf`. **CAUTION: BEWARE OF SHELL INJECTIONS!**

- `command_prefix`:   prefix `wkhtmltopdf` with some command or a command with options
                      (e.g. `xvfb-run -a`, `sudo` ..)

- `delete_temporary`: immediately remove temp files after generation

## Contribution; how to run tests

You're more than welcome ot submit patches. Please run `mix test` to ensure at bit of stability. Tests require a full-fledged environment, with all of `wkhtmltopdf`, `xvfb` and `chrome-headless-render-pdf` available path. Also make to to have run `npm install` in the app's base directory (will install chrome-headless-render-pdf non-globally in there). With all these installed, `mix test` should run smoothly.

_Hint_: Getting `:enoent` errors ususally means that chrome or xvfb couldn't be run. Yes, this should output a nicer error.

## Heroku Setup

If you want to use this project on heroku, you can use buildpacks instead of binaries
to load `pdftk` and `wkhtmltopdf`:

__note:__ The list also includes Elixir and Phoenix buildpacks to show you that they
must be placed after `pdftk` and `wkhtmltopdf`. It won't work if you load the
Elixir and Phoenix buildpacks first.

## Running non-patched wkhtmltopdf headless

This section only applies to `wkhtmltopdf` users using wkhtmltopdf w/o the qt patch. If you are using the latest 0.12 binaries from (recommended) you can safely skip this section.

If you want to run `wkhtmltopdf` with an unpatched verison of webkit that requires
an X Window server, but your server (or Mac) does not have one installed,
you may find the `command_prefix` handy:

PdfGenerator.generate "<html..", command_prefix: "xvfb-run"

This can also be configured globally in your `config/config.exs`:

config :pdf_generator,
    command_prefix: "/usr/bin/xvfb-run"

If you will be generating multiple PDFs simultaneously, or in rapid succession,
you will need to configure `xvfb-run` to search for a free X server number,
or set the server number explicitly. You can use the `command_prefix` to pass
options to the `xvfb-run` command.

config :pdf_generator,
    command_prefix: ["xvfb-run", "-a"]

# Documentation

For more info, read the [docs on hex]( or issue
`h PdfGenerator.generate` in your iex shell.

# Known issues

Unfortunately, with Elixir 1.7+ `System.cmd` seems to pass parameters
differently to the environment than it did before, now requiring shell options
like `--foo=bar` to be split up as `["--foo", "bar"]`. This behaviour seemingly
went away with OTP 22 in May 2019 and Elixir 1.8.2. So if you run into issues,
try upgrading to the latest Erlang/OTP and Elixir first, and do not hesitate
file a report.

# Contributing

Contributions (Issues, PRs…) are more than welcome. Please ave a quick read at 
the [Contribution tips](./, though. It's basically about scope 
and kindness.