How do I merge these two varnish backends? - varnish

Question

I am using thumbor and s3.
I want to use varnish infront of them.
I know how to do place varnish in each of them but I can't combine the two
varnish setup for thumbor
vcl 4.0;
import directors;
backend thumbor1 { .host ="127.0.0.1"; .port="8888"; .max_connections = 200; .connect_timeout = 5s; .between_bytes_timeout = 5s; }
# backend thumbor2 { .host ="127.0.0.1"; .port="9002"; .max_connections = 200; .connect_timeout = 5s; .between_bytes_timeout = 5s; }
acl internal {
"localhost";
"127.0.0.1";
}
sub vcl_init {
new vdir = directors.round_robin();
vdir.add_backend(thumbor1);
# vdir.add_backend(thumbor2);
}
sub vcl_recv {
set req.backend_hint = vdir.backend();
if (req.method == "PURGE") {
if (!client.ip ~ internal) {
return (synth(405, "This IP is not allowed to send PURGE requests."));
}
return (purge);
}
if (req.url ~ "\?$") {
set req.url = regsub(req.url, "\?$", "");
}
return (hash);
}
varnish setup for s3
vcl 4.0;
backend default
{
.host = "my.bucket.s3.amazonaws.com";
.port = "80";
}
sub vcl_backend_fetch
{
set bereq.http.Host = "my.bucket.s3.amazonaws.com";
set bereq.http.Date = now;
}
I'd like the final result would be something like
client => varnish => thumbor => s3 (thumbnail image)
client => varnish => s3 (normal image)

Answer 1

You should put 2 backend blocks in the one file. Then in the vcl_recv you should set which backend do you want by some header, url path etc.
To set which backend to use, you could use:
set req.backend_hint = thumbor1;
# Or
set req.backend_hint = default;
There you could find how I've applied it to use 2 backends - localhost:3000 & localhost:8080: https://github.com/new-fantastic/vsf-cache-varnish/blob/master/docker/varnish/shared.vcl