Probe Proxy implementation

probe_proxy.vcl

#
# Probe Proxy v1.0
#

import directors;
import kvstore;
import probe_proxy;
import std;

acl probe_proxy_local {
    "127.0.0.0"/8;
    "::1"/128;
}

sub vcl_init
{
    # Settings
    new probe_proxy_opts = kvstore.init();

    # Route all probes to this VCL
    probe_proxy.global(probe_proxy.self());

    # All probes will be forwarded to this gateway
    # Parent VCL fills this in with probe gateway backends
    new probe_proxy_gateway = directors.fallback();
}

sub vcl_recv
{
    if (probe_proxy.is_probe()) {
        # Security
        if (probe_proxy_opts.get("token")) {
            if (client.ip ~ probe_proxy_local) {
                # TODO sign
            } else {
                # TODO validate
            }
        }

        return (hash);
    }
}

sub vcl_hash
{
    if (probe_proxy.is_probe()) {
        hash_data(req.url);
        hash_data(probe_proxy.get_backend_path());
        return (lookup);
    }
}

sub vcl_backend_fetch
{
    if (probe_proxy.is_probe()) {
        # Use the probe gateway
        if (std.health(probe_proxy_gateway.backend()) && !probe_proxy.is_marked() && bereq.retries == 0)) {
            set bereq.backend = probe_proxy_gateway.backend();

            # Dont loop around
            probe_proxy.mark();
        }
        # We are a real probe, goto the probe backend
        else  {
            if (probe_proxy.get_backend()) {
                set beresp.backend = probe_proxy.get_backend();
            } else {
                set beresp.backend = goto.dns_backend(probe_proxy.get_backend_path());
            }

            probe_proxy.clear();
            probe_proxy.force_fresh();
            set bereq.first_byte_timeout = probe_proxy.get_timeout();
        }

        return (fetch);
    }
}

sub vcl_backend_response
{
    if (probe_proxy.is_probe()) {
        set beresp.ttl = probe_proxy.get_interval();
        set beresp.grace = 0s;
        set beresp.keep = 0s;
        return (deliver);
    }
}

sub vcl_backend_error
{
    if (probe_proxy.is_probe()) {
        if (bereq.retries == 0 && !probe_proxy.is_marked()) {
            return (retry);
        }
    }
}

sub vcl_deliver
{
    # Strip the body
    if (probe_proxy.is_probe()) {
        return (synth(resp.status, resp.reason));
    }
}

sub vcl_synth
{
    if (probe_proxy.is_probe()) {
        synthetic("Varnish probe proxy");
        return (deliver);
    }
}

# EOF