The image vmod provides a tool for image modification and optimization.
import image;
import headerplus;
sub vcl_backend_response {
headerplus.init(beresp);
if (beresp.http.content-type == "image/jpeg" ||
beresp.http.content-type == "image/png") {
if (bereq.http.Accept ~ "image/webp") {
image.webp();
}
headerplus.attr_set("Vary", "Accept");
}
headerplus.write();
}
VOID webp([INT quality = 75], [INT resize_width = 0], [INT resize_height = 0], [BOOL lossless = 0], [INT lossless_level = 6])
Convert an image to the WebP format and store it in cache. Optionally scale,
resize or change the quality of conversion. Scaling is done by using only one
of resize_width or resize_height. quality and lossless are mutually
exclusive options. The supported content types to convert are image/png and
image/jpeg. When called this function disables streaming.
It should not be re-enabled for proper functionality.
Note: quality is a number between 0 and 100, a lower number will result in a smaller size but lower quality.
mode is a number between 0 and 9, a lower number is faster but produces a larger file size.
Arguments:
quality accepts type INT with a default value of 75 optional
resize_width accepts type INT with a default value of 0 optional
resize_height accepts type INT with a default value of 0 optional
lossless accepts type BOOL with a default value of 0 optional
lossless_level accepts type INT with a default value of 6 optional
Type: Function
Returns: None
The image VMOD is available in the varnish-plus-vmods-extras package.