Using custom error pages in Varnish

While playing around with the fancy error pages I wanted to use them with Varnish as well. Since there is no means to include a file or serve a file from Varnish (without serving from a back end server), I went with inline C snippet to read and serve the error pages. Please note that the style sheet and the images are being served from a CDN. Otherwise it will have to be cached prior to the back end server becoming inaccessible. Here is the whole vcl_error sub. You will notice that we fall back to default Varnish error page for anything other than 5XX errors.

[code lang=’c’]sub vcl_error {
set obj.http.Content-Type = “text/html; charset=utf-8”;

if ( obj.status >= 500 && obj.status <= 505) { C{ #include

FILE * pFile;
char content [100];
char page [10240];
char fname [50];

page[0] = ‘\0’;
sprintf(fname, “/var/www/errors/%d.html”, VRT_r_obj_status(sp));

pFile = fopen(fname, “r”);
while (fgets(content, 100, pFile)) {
strcat(page, content);
VRT_synth_page(sp, 0, page, ““, vrt_magic_string_end);
} else {
synthetic {”

“} obj.status ” ” obj.response {“

Error “} obj.status ” ” obj.response {“

“} obj.response {“

Guru Meditation:

XID: “} req.xid {“



return (deliver);

Hope someone will find this useful as I had to put some effort to find out all the internal Varnish function names

Fancy HTTP Error pages – 5xx

If you hadn’t noticed my site was giving HTTP 500 errors last couple of days. The issue was found to be a segfault and it’s fixed now. That got me to come up with a set of funny and slick HTTP error pages. I only came up with HTTP 5xx error pages, I believe HTTP 4xx error pages should be specific to the site. You can download them here. If you want to take a peek, here is the list. HTTP 500, 501, 502, 503, 504, 505. Feel free to modify them and share what you come up with.