flagshipio/varnish repository overview

# specify the VCL syntax version to use
vcl 4.0;

import std;
import cookie;
import blob;
import header;

# import vmod_flagship to perfom experimentation and feature flag in varnish
import flagship;

# we won't use any static backend, but Varnish still need a default one
backend default none;

# initiate the flagship instance
sub vcl_init {
  flagship.init(envID=std.getenv("FS_ENV_ID"), apiKey=std.getenv("FS_API_KEY"), pollingInterval=std.integer(std.getenv("FS_POLLING_INTERVAL"), 10), logLevel=std.getenv("FS_LOG_LEVEL"), trackingEnabled=std.integer(std.getenv("FS_TRACKING_ENABLED"), 0));
}

sub vcl_recv {
	unset req.http.x-cache;

  # the visitor ID
  set req.http.X-VISITOR-ID = "" + req.xid;

  # initialize the visitor context
  set req.http.X-VISITOR-CONTEXT = "";

  # fillout the chrome device as context for example
  if (req.http.User-Agent ~ "Chrome") {
      set req.http.X-VISITOR-CONTEXT  = "device:chrome";
  } else if (req.http.User-Agent ~ "Mozilla.*Firefox*") {
      set req.http.X-VISITOR-CONTEXT  = "device:firefox";
  } else {
      set req.http.X-VISITOR-CONTEXT  = "device:edge";
  }

  if (req.url ~ "^/") {
    return (synth(200, "Flagship"));
  }

  return(hash);
}

sub vcl_hash {
  # this is where we should call flagship code to compute flag values
  set req.http.X-FS-FLAGVALUES = flagship.compute_flags(req.http.X-VISITOR-ID, req.http.X-VISITOR-CONTEXT);
    
  # you can also call flagship to get flag
  set req.http.X-FS-FLAGSTRING = flagship.get_flag_string(req.http.X-VISITOR-ID, req.http.X-VISITOR-CONTEXT, "color", "white", 1);
      
  # you can also call flagship to get flag
  set req.http.X-FS-FLAGBOOL = flagship.get_flag_bool(req.http.X-VISITOR-ID, req.http.X-VISITOR-CONTEXT, "IsVIP", 0, 1);

  # you can also call flagship to get flag
  set req.http.X-FS-FLAGNUMBER = flagship.get_flag_number(req.http.X-VISITOR-ID, req.http.X-VISITOR-CONTEXT, "price", 9.99, 1);

  # the builtin.vcl will take care of also varying cache on those flag values
  hash_data(req.http.X-FS-FLAGVALUES);
      
}

# Log cache miss, hit, pass, pipe & synth in header
sub vcl_hit {
	set req.http.x-cache = "hit";
}

sub vcl_miss {
	set req.http.x-cache = "miss";
}

sub vcl_pass {
	set req.http.x-cache = "pass";
}

sub vcl_pipe {
	set req.http.x-cache = "pipe uncacheable";
}

sub vcl_synth {
	set resp.http.Content-Type = "text/html; charset=utf-8";
  set resp.http.Retry-After = "5";
  set resp.body = {"<!DOCTYPE html>
<html>
  <head>
    <title>"} + resp.reason + {"</title>
  </head>
  <body>
    <h1>"} + resp.reason + {"</h1>
    <p>Visitor ID: "} + req.http.X-VISITOR-ID + {"</p>
    <p>Visitor context: "} + req.http.X-VISITOR-CONTEXT + {"</p>
    <p>Flagship getAllFlags: "} + req.http.X-FS-FLAGVALUES + {"</p>
  </body>
</html>
"};

  return (deliver);
}

# This function is used when a request is sent by our backend
sub vcl_backend_response {
  # If we find our layout cookie we copy it to a header and then we remove it so we can cache the page
  # Later after we deliver the page from cache we set the cookie from the header and then remove that header
  if ( beresp.http.Set-Cookie ) {
    set beresp.http.fs-cookie = beresp.http.Set-Cookie;
    unset beresp.http.Set-Cookie;
  }
}

sub vcl_deliver {

  if(resp.http.fs-cookie){
    set resp.http.Set-Cookie = resp.http.fs-cookie;
    unset resp.http.fs-cookie;
  }

  # Add flagship values to cookie if set
  if (req.http.X-FS-FLAGVALUES) {
    header.append(resp.http.Set-Cookie,"FS-FLAGVALUES=" + blob.transcode(encoded=req.http.X-FS-FLAGVALUES, encoding=URL) + "; Domain=localhost");
  } 

  if (obj.uncacheable) {
		set resp.http.x-cache = req.http.x-cache + " uncacheable" ;
	} else {
		set resp.http.x-cache = req.http.x-cache + " cached" ;
	}
}

# we need the configuration file at /etc/varnish/default.vcl,
# our workdir has to be mounted as tmpfs to avoid disk I/O,
# and we'll use port 8080 to talk to our container (internally listening on 80)
docker run -it -p 8080:80 -t --name varnish-standalone \
 -v /path/to/default.vcl:/etc/varnish/default.vcl:ro \
 --tmpfs /var/lib/varnish/varnishd:exec \
 -e "FS_ENV_ID=ENV_ID" \
 -e "FS_API_KEY=API_KEY" \
 -e "FS_POLLING_INTERVAL=50" \
 -e "FS_LOG_LEVEL=debug" \
 -e "FS_TRACKING_ENABLED=0" \
 flagshipio/varnish:7.2

# update the default.vcl in your container
docker cp new_default.vcl running_container:/etc/varnish/default.vcl
# run varnishreload
docker exec running_container varnishreload

docker run varnish varnishreload -h