Wkhtmltopdf seems to embed fonts in the PDF in an unpredictable way - css

Question

I have developed a small engine that produces PDFs using wkhtmltopdf.
While working on my PC (Fedora 24) the generated PDF looked ok. After installing the software on a test server (CentOS 7), I found that the generated PDFs are slightly different.
I'm using a standalone (not installed via package manager) version of the tool. More precisely I'm using version wkhtmltopdf 0.12.3 (with patched qt)
After some investigation I noticed that the PDFs produced on my system contained these fonts:
Instead the PDF generated on the server contains these:
In the CSS I'm using these fonts for the whole document:
/* open-sans-300 - latin */
#font-face {
font-family: 'Open-Sans-Light';
font-style: normal;
font-weight: 300;
src: url('../fonts/open-sans-v13-latin-300.eot'); /* IE9 Compat Modes */
src: local('Open Sans Light'), local('OpenSans-Light'),
url('../fonts/open-sans-v13-latin-300.eot?#iefix') format('embedded-opentype'), /* IE6-IE8 */
url('../fonts/open-sans-v13-latin-300.woff2') format('woff2'), /* Super Modern Browsers */
url('../fonts/open-sans-v13-latin-300.woff') format('woff'), /* Modern Browsers */
url('../fonts/open-sans-v13-latin-300.ttf') format('truetype'), /* Safari, Android, iOS */
url('../fonts/open-sans-v13-latin-300.svg#OpenSans') format('svg'); /* Legacy iOS */
}
/* open-sans-regular - latin */
#font-face {
font-family: 'Open-Sans-Regular';
font-style: normal;
font-weight: 400;
src: url('../fonts/open-sans-v13-latin-regular.eot'); /* IE9 Compat Modes */
src: local('Open Sans'), local('OpenSans'),
url('../fonts/open-sans-v13-latin-regular.eot?#iefix') format('embedded-opentype'), /* IE6-IE8 */
url('../fonts/open-sans-v13-latin-regular.woff2') format('woff2'), /* Super Modern Browsers */
url('../fonts/open-sans-v13-latin-regular.woff') format('woff'), /* Modern Browsers */
url('../fonts/open-sans-v13-latin-regular.ttf') format('truetype'), /* Safari, Android, iOS */
url('../fonts/open-sans-v13-latin-regular.svg#OpenSans') format('svg'); /* Legacy iOS */
}
/* open-sans-300italic - latin */
#font-face {
font-family: 'Open-Sans-Light-Italic';
font-style: italic;
font-weight: 300;
src: url('../fonts/open-sans-v13-latin-300italic.eot'); /* IE9 Compat Modes */
src: local('Open Sans Light Italic'), local('OpenSansLight-Italic'),
url('../fonts/open-sans-v13-latin-300italic.eot?#iefix') format('embedded-opentype'), /* IE6-IE8 */
url('../fonts/open-sans-v13-latin-300italic.woff2') format('woff2'), /* Super Modern Browsers */
url('../fonts/open-sans-v13-latin-300italic.woff') format('woff'), /* Modern Browsers */
url('../fonts/open-sans-v13-latin-300italic.ttf') format('truetype'), /* Safari, Android, iOS */
url('../fonts/open-sans-v13-latin-300italic.svg#OpenSans') format('svg'); /* Legacy iOS */
}
/* open-sans-700 - latin */
#font-face {
font-family: 'Open-Sans-Bold';
font-style: normal;
font-weight: 700;
src: url('../fonts/open-sans-v13-latin-700.eot'); /* IE9 Compat Modes */
src: local('Open Sans Bold'), local('OpenSans-Bold'),
url('../fonts/open-sans-v13-latin-700.eot?#iefix') format('embedded-opentype'), /* IE6-IE8 */
url('../fonts/open-sans-v13-latin-700.woff2') format('woff2'), /* Super Modern Browsers */
url('../fonts/open-sans-v13-latin-700.woff') format('woff'), /* Modern Browsers */
url('../fonts/open-sans-v13-latin-700.ttf') format('truetype'), /* Safari, Android, iOS */
url('../fonts/open-sans-v13-latin-700.svg#OpenSans') format('svg'); /* Legacy iOS */
}
So why is wkhtmltopdf embedding extra fonts?
How can I make sure that wkhtmltopdf uses Open Sans only and that I can obtain the same PDF no matter which system I run the software on?
Right now it seems to pick randomly fonts it finds available in the system, besides the ones I specified :|

Answer 1

On Windows I had the opposite: on the development machine fonts were embedded in the PDF just fine, but on other machines (For example the production server) fonts were missing and not embedded.
I investigated the log files and all fonts were properly downloaded from the machine as expected when a PDF was generated.
As last resort I installed all fonts on the system of the server (via control panel). This resolved the issue....
I think this has to do with a difference in the fonts installed on the system.