Pandoc 转换为 pdf 不适用于 heroku

Question

我在 Rails 应用程序上有一个 ruby，它使用 pandoc-ruby 将 markdown 文件转换为 pdf。 pandoc-ruby 需要安装 pandoc。 要成功转换为 pdf，还需要存在 pdflatex。 在本地（在 Mac 和 Ubuntu 18.04 上测试）如果pandoc 、 texlive-latex-recommended和texlive-fonts-recommended软件包，一切正常。 部署到 heroku 时，事情变得有点棘手。 要在 heroku 上安装所有软件包，我使用了 Aptfile 方法，但我无法解决这个问题。

方法一：Aptfile

我已经指定了这个 Aptfile：

# Aptfile
texlive-latex-recommended
texlive-fonts-recommended
https://github.com/jgm/pandoc/releases/download/2.11.3.2/pandoc-2.11.3.2-1-amd64.deb

我得到的错误是：

2021-01-22T21:46:03.478937+00:00 app[web.1]: [6ac45926-62f3-48bf-98b5-8f7c1022a02f] RuntimeError (warning: kpathsea: configuration file texmf.cnf not found in these directories: /etc/texmf/web2c:/usr/local/share/texmf/web2c:/usr/share/texmf/web2c:/usr/share/texlive/texmf-dist/web2c:/app/.apt/share/texmf/web2c.
2021-01-22T21:46:03.478938+00:00 app[web.1]:
2021-01-22T21:46:03.478938+00:00 app[web.1]: kpathsea: Running mktexfmt pdflatex.fmt
2021-01-22T21:46:03.478940+00:00 app[web.1]: warning: kpathsea: configuration file texmf.cnf not found in these directories: /etc/texmf/web2c:/usr/local/share/texmf/web2c:/usr/share/texmf/web2c:/usr/share/texlive/texmf-dist/web2c:/app/.apt/share/texmf/web2c.
2021-01-22T21:46:03.478940+00:00 app[web.1]: /app/.apt/usr/bin/mktexfmt: kpsewhich -var-value=TEXMFROOT failed, aborting early.
2021-01-22T21:46:03.478942+00:00 app[web.1]: BEGIN failed--compilation aborted at /app/.apt/usr/bin/mktexfmt line 28.
2021-01-22T21:46:03.478942+00:00 app[web.1]: warning: kpathsea: configuration file texmf.cnf not found in these directories: /etc/texmf/web2c:/usr/local/share/texmf/web2c:/usr/share/texmf/web2c:/usr/share/texlive/texmf-dist/web2c:/app/.apt/share/texmf/web2c.
2021-01-22T21:46:03.478942+00:00 app[web.1]:
2021-01-22T21:46:03.478943+00:00 app[web.1]: kpathsea: Running mktexfmt pdflatex.fmt
2021-01-22T21:46:03.478943+00:00 app[web.1]: warning: kpathsea: configuration file texmf.cnf not found in these directories: /etc/texmf/web2c:/usr/local/share/texmf/web2c:/usr/share/texmf/web2c:/usr/share/texlive/texmf-dist/web2c:/app/.apt/share/texmf/web2c.
2021-01-22T21:46:03.478944+00:00 app[web.1]: /app/.apt/usr/bin/mktexfmt: kpsewhich -var-value=TEXMFROOT failed, aborting early.
2021-01-22T21:46:03.478944+00:00 app[web.1]: BEGIN failed--compilation aborted at /app/.apt/usr/bin/mktexfmt line 28.
2021-01-22T21:46:03.478945+00:00 app[web.1]: Error producing PDF.
2021-01-22T21:46:03.478947+00:00 app[web.1]: This is pdfTeX, Version 3.14159265-2.6-1.40.20 (TeX Live 2019/Debian) (preloaded format=pdflatex)
2021-01-22T21:46:03.478947+00:00 app[web.1]: I can't find the format file `pdflatex.fmt'!
2021-01-22T21:46:03.478947+00:00 app[web.1]:
2021-01-22T21:46:03.478948+00:00 app[web.1]: ):

我尝试使用heroku run bash来尝试弄清楚发生了什么。 所有的包似乎都安装好了，但是一个简单的 pandoc 命令失败了，见下面的 output。

~ $ pandoc -v
pandoc 2.11.3.2
Compiled with pandoc-types 1.22, texmath 0.12.1, skylighting 0.10.2,
citeproc 0.3.0.3, ipynb 0.1.0.1
User data directory: /app/.local/share/pandoc or /app/.pandoc
Copyright (C) 2006-2020 John MacFarlane. Web:  https://pandoc.org
This is free software; see the source for copying conditions. There is no
warranty, not even for merchantability or fitness for a particular purpose.
~ $ pdflatex -v
pdfTeX 3.14159265-2.6-1.40.20 (TeX Live 2019/Debian)
kpathsea version 6.3.1
Copyright 2019 Han The Thanh (pdfTeX) et al.
There is NO warranty.  Redistribution of this software is
covered by the terms of both the pdfTeX copyright and
the Lesser GNU General Public License.
For more information about these matters, see the file
named COPYING and the pdfTeX source.
Primary author of pdfTeX: Han The Thanh (pdfTeX) et al.
Compiled with libpng 1.6.37; using libpng 1.6.37
Compiled with zlib 1.2.11; using zlib 1.2.11
Compiled with xpdf version 4.01
~ $ pandoc test.md -o test.pdf
warning: kpathsea: configuration file texmf.cnf not found in these directories: /etc/texmf/web2c:/usr/local/share/texmf/web2c:/usr/share/texmf/web2c:/usr/share/texlive/texmf-dist/web2c:/app/.apt/share/texmf/web2c.

kpathsea: Running mktexfmt pdflatex.fmt
warning: kpathsea: configuration file texmf.cnf not found in these directories: /etc/texmf/web2c:/usr/local/share/texmf/web2c:/usr/share/texmf/web2c:/usr/share/texlive/texmf-dist/web2c:/app/.apt/share/texmf/web2c.
/app/.apt/usr/bin/mktexfmt: kpsewhich -var-value=TEXMFROOT failed, aborting early.
BEGIN failed--compilation aborted at /app/.apt/usr/bin/mktexfmt line 28.
warning: kpathsea: configuration file texmf.cnf not found in these directories: /etc/texmf/web2c:/usr/local/share/texmf/web2c:/usr/share/texmf/web2c:/usr/share/texlive/texmf-dist/web2c:/app/.apt/share/texmf/web2c.

kpathsea: Running mktexfmt pdflatex.fmt
warning: kpathsea: configuration file texmf.cnf not found in these directories: /etc/texmf/web2c:/usr/local/share/texmf/web2c:/usr/share/texmf/web2c:/usr/share/texlive/texmf-dist/web2c:/app/.apt/share/texmf/web2c.
/app/.apt/usr/bin/mktexfmt: kpsewhich -var-value=TEXMFROOT failed, aborting early.
BEGIN failed--compilation aborted at /app/.apt/usr/bin/mktexfmt line 28.
Error producing PDF.
This is pdfTeX, Version 3.14159265-2.6-1.40.20 (TeX Live 2019/Debian) (preloaded format=pdflatex)
I can't find the format file `pdflatex.fmt'!

方法 2：自定义构建包

我还尝试了 2 个用于 TeX Live 的自定义构建包，可在此处和此处找到。 它看起来更有希望，但在转换为 pdf 时仍然会产生错误。 请参阅下面的 heroku 运行 bash 中的 output。

~ $ pandoc -v
pandoc 2.11.3.2
Compiled with pandoc-types 1.22, texmath 0.12.1, skylighting 0.10.2,
citeproc 0.3.0.3, ipynb 0.1.0.1
User data directory: /app/.local/share/pandoc or /app/.pandoc
Copyright (C) 2006-2020 John MacFarlane. Web:  https://pandoc.org
This is free software; see the source for copying conditions. There is no
warranty, not even for merchantability or fitness for a particular purpose.
~ $ pdflatex -v
pdfTeX 3.14159265-2.6-1.40.21 (TeX Live 2020)
kpathsea version 6.3.2
Copyright 2020 Han The Thanh (pdfTeX) et al.
There is NO warranty.  Redistribution of this software is
covered by the terms of both the pdfTeX copyright and
the Lesser GNU General Public License.
For more information about these matters, see the file
named COPYING and the pdfTeX source.
Primary author of pdfTeX: Han The Thanh (pdfTeX) et al.
Compiled with libpng 1.6.37; using libpng 1.6.37
Compiled with zlib 1.2.11; using zlib 1.2.11
Compiled with xpdf version 4.02
~ $ pandoc test.md -o test.pdf
Error producing PDF.
! LaTeX Error: File `xcolor.sty' not found.

Type X to quit or <RETURN> to proceed,
or enter new name. (Default extension: sty)

Enter file name:
! Emergency stop.
<read *>

l.36 \IfFileExists

Answer 1

经过相当多的试验和错误，我找到了一个可行的解决方案。

正如@mb21 提到的，Docker 图像可能是长期的最佳选择。 Heroku 支持 Docker 图像。 但是，我想避免 dockerizing 整个应用程序来解决这个问题。

在为 Heroku 找到支持添加自定义 TeX Live 包（ 此类 buildpack 的一个示例）的TeX Live buildpack 后，转换错误为: LaTeX Error. File 'xcolor.sty' not found. : LaTeX Error. File 'xcolor.sty' not found.

我使用tlmgr获取有关丢失文件的一些信息。 运行tlmgr search --global --file xcolor.sty可以解决问题，并显示有一个名为 xcolor 的xcolor 。 安装后，我们会遇到下一个错误，下一个，下一个。 最后，我最终安装了 2 个 collections，它们对于 Heroku 来说足够小（注意 500MB 的 slug 大小限制），并包含 pandoc 成功转换所需的一切。 这两个是collection-fontsrecommended和collection-latexrecommended 。

将texlive.packages文件添加到应用程序的根目录就可以了。 它被 buildpack 识别，并使用tlmgr为您安装所有指定的包。

# texlive.packages

collection-fontsrecommended
collection-latexrecommended