Varnish MISS on some URL's, but HITS on other - magento2

Question

We are using Magento 2 with Varnish cache
We only get Varnish Cache HIT on very few /catalogsearch/result/ pages, and we really can not figure out why we don't get cache HIT on all /catalogsearch/result/ pages.
Please help us in the right direction :-)
Ex.
we always get HIT on this url
https://www.babygear.dk/catalogsearch/result/?q=bog
We always get MISS on a lot of other search queries
https://www.babygear.dk/catalogsearch/result/?q=black
https://www.babygear.dk/catalogsearch/result/?q=box
https://www.babygear.dk/catalogsearch/result/?q=box
Here is our varnish.vlc
# VCL version 5.0 is not supported so it should be 4.0 even though actually used Varnish version is 5
vcl 4.0;
import std;
# The minimal Varnish version is 5.0
# For SSL offloading, pass the following header in your proxy server or load balancer: 'X-Forwarded-Proto: https'
backend default {
.host = "127.0.0.1";
.port = "8080";
.first_byte_timeout = 600s;
}
acl purge {
"127.0.0.1";
}
sub vcl_recv {
if (req.method == "PURGE") {
if (client.ip !~ purge) {
return (synth(405, "Method not allowed"));
}
# To use the X-Pool header for purging varnish during automated deployments, make sure the X-Pool header
# has been added to the response in your backend server config. This is used, for example, by the
# capistrano-magento2 gem for purging old content from varnish during it's deploy routine.
if (!req.http.X-Magento-Tags-Pattern && !req.http.X-Pool) {
return (synth(400, "X-Magento-Tags-Pattern or X-Pool header required"));
}
if (req.http.X-Magento-Tags-Pattern) {
ban("obj.http.X-Magento-Tags ~ " + req.http.X-Magento-Tags-Pattern);
}
if (req.http.X-Pool) {
ban("obj.http.X-Pool ~ " + req.http.X-Pool);
}
return (synth(200, "Purged"));
}
if (req.method != "GET" &&
req.method != "HEAD" &&
req.method != "PUT" &&
req.method != "POST" &&
req.method != "TRACE" &&
req.method != "OPTIONS" &&
req.method != "DELETE") {
/* Non-RFC2616 or CONNECT which is weird. */
return (pipe);
}
# We only deal with GET and HEAD by default
if (req.method != "GET" && req.method != "HEAD") {
return (pass);
}
# Bypass shopping cart, checkout
if (req.url ~ "/checkout") {
return (pass);
}
# Bypass health check requests
if (req.url ~ "/pub/health_check.php") {
return (pass);
}
# Set initial grace period usage status
set req.http.grace = "none";
# normalize url in case of leading HTTP scheme and domain
set req.url = regsub(req.url, "^http[s]?://", "");
# collect all cookies
std.collect(req.http.Cookie);
# Compression filter. See https://www.varnish-cache.org/trac/wiki/FAQ/Compression
if (req.http.Accept-Encoding) {
if (req.url ~ "\.(jpg|jpeg|png|gif|gz|tgz|bz2|tbz|mp3|ogg|swf|flv)$") {
# No point in compressing these
unset req.http.Accept-Encoding;
} elsif (req.http.Accept-Encoding ~ "gzip") {
set req.http.Accept-Encoding = "gzip";
} elsif (req.http.Accept-Encoding ~ "deflate" && req.http.user-agent !~ "MSIE") {
set req.http.Accept-Encoding = "deflate";
} else {
# unknown algorithm
unset req.http.Accept-Encoding;
}
}
# Remove all marketing get parameters to minimize the cache objects
if (req.url ~ "(\?|&)(gclid|ff|fp|cx|ie|cof|siteurl|zanpid|origin|fbclid|mc_[a-z]+|utm_[a-z]+|_bta_[a-z]+)=") {
set req.url = regsuball(req.url, "(gclid|ff|fp|cx|ie|cof|siteurl|zanpid|origin|fbclid|mc_[a-z]+|utm_[a-z]+|_bta_[a-z]+)=[-_A-z0-9+()%.]+&?", "");
set req.url = regsub(req.url, "[?|&]+$", "");
}
# Static files caching
if (req.url ~ "^/(pub/)?(media|static)/") {
# Static files should not be cached by default
#return (pass);
# But if you use a few locales and don't use CDN you can enable caching static files by commenting previous line (#return (pass);) and uncommenting next 3 lines
unset req.http.Https;
unset req.http.X-Forwarded-Proto;
unset req.http.Cookie;
}
return (hash);
}
sub vcl_hash {
if (req.http.cookie ~ "X-Magento-Vary=") {
hash_data(regsub(req.http.cookie, "^.*?X-Magento-Vary=([^;]+);*.*$", "\1"));
}
# For multi site configurations to not cache each other's content
if (req.http.host) {
hash_data(req.http.host);
} else {
hash_data(server.ip);
}
# To make sure http users don't see ssl warning
if (req.http.X-Forwarded-Proto) {
hash_data(req.http.X-Forwarded-Proto);
}
if (req.url ~ "/graphql") {
call process_graphql_headers;
}
}
sub process_graphql_headers {
if (req.http.Store) {
hash_data(req.http.Store);
}
if (req.http.Content-Currency) {
hash_data(req.http.Content-Currency);
}
}
sub vcl_backend_response {
set beresp.grace = 3d;
if (beresp.http.content-type ~ "text") {
set beresp.do_esi = true;
}
if (bereq.url ~ "\.js$" || beresp.http.content-type ~ "text") {
set beresp.do_gzip = true;
}
if (beresp.http.X-Magento-Debug) {
set beresp.http.X-Magento-Cache-Control = beresp.http.Cache-Control;
}
# cache only successfully responses
if (beresp.status != 200) {
set beresp.ttl = 0s;
set beresp.uncacheable = true;
return (deliver);
} elsif (beresp.http.Cache-Control ~ "private") {
set beresp.uncacheable = true;
set beresp.ttl = 44400s;
return (deliver);
}
# validate if we need to cache it and prevent from setting cookie
if (beresp.ttl > 0s && (bereq.method == "GET" || bereq.method == "HEAD")) {
unset beresp.http.set-cookie;
}
# If page is not cacheable then bypass varnish for 2 minutes as Hit-For-Pass
if (beresp.ttl <= 0s ||
beresp.http.Surrogate-control ~ "no-store" ||
(!beresp.http.Surrogate-Control &&
beresp.http.Cache-Control ~ "no-cache|no-store") ||
beresp.http.Vary == "*") {
# Mark as Hit-For-Pass for the next 2 minutes
set beresp.ttl = 120s;
set beresp.uncacheable = true;
}
return (deliver);
}
sub vcl_deliver {
if (resp.http.X-Magento-Debug) {
if (resp.http.x-varnish ~ " ") {
set resp.http.X-Magento-Cache-Debug = "HIT";
set resp.http.Grace = req.http.grace;
} else {
set resp.http.X-Magento-Cache-Debug = "MISS";
}
} #else {
# unset resp.http.Age;
# }
# Not letting browser to cache non-static files.
if (resp.http.Cache-Control !~ "private" && req.url !~ "^/(pub/)?(media|static)/") {
set resp.http.Pragma = "no-cache";
set resp.http.Expires = "-1";
set resp.http.Cache-Control = "no-store, no-cache, must-revalidate, max-age=0";
}
unset resp.http.X-Magento-Debug;
unset resp.http.X-Magento-Tags;
unset resp.http.X-Powered-By;
unset resp.http.Server;
unset resp.http.X-Varnish;
unset resp.http.Via;
unset resp.http.Link;
}
sub vcl_hit {
if (obj.ttl >= 0s) {
# Hit within TTL period
return (deliver);
}
if (std.healthy(req.backend_hint)) {
if (obj.ttl + 3000000s > 0s) {
# Hit after TTL expiration, but within grace period
set req.http.grace = "normal (healthy server)";
return (deliver);
} else {
# Hit after TTL and grace expiration
return (miss);
}
} else {
# server is not healthy, retrieve from cache
set req.http.grace = "unlimited (unhealthy server)";
return (deliver);
}
}

Answer 1

It's a bit tough to judge what's really going on, because there's both a Varnish cache in front of Magento and Cloudflare as the CDN.
A no-cache/no-store Cache-Control value
What I am seeing in general for your searches, is the following Cache-Control value:
cache-control: no-store, no-cache, must-revalidate, max-age=0
Based on this value, Varnish will decide not to cache. In the response headers of must of your search results you will see that Age: 0 is set. This means that Varnish doesn't hold the value in cache.
A cached search result that shouldn't be cacheable
However, weirdly enough https://www.babygear.dk/catalogsearch/result/?q=bog does have a an Age header with a value greater than zero:
age: 38948
This means it's been in cache for 38948 seconds. But really, this shouldn't be happening, because the page is not supposed to be cacheable.
Making search results cacheable:
Please make sure you have a Cache-Control header that allows caching, if you want to cache search results.
Example:
Cache-Control: public, s-maxage=3600
Debugging using Varnishlog
If you really want to know what happens in behind the scenes in Varnish, you can perform some debugging using the varnishlog binary.
You could run the following command to get debug output:
varnishlog -g request -q "ReqUrl eq '/catalogsearch/result/\?q=bog'"
This will print some very verbose logs on how Varnish treats the URL that causes the hit. You can add this output to your question, and I can try to examine what's going on.
FYI: I wrote a very detailed blog post about varnishlog a couple of years ago. Please go to https://feryn.eu/blog/varnishlog-measure-varnish-cache-performance/ to have a look, and to learn.
What's Cloudflare doing?
All that being said, I have no clue what the impact of Cloudflare is on the cacheability of the website. The varnishlog output will give us some insight, but if those results diverge from reality, Cloudflare is probably getting in our way.
Keep this in mind while debugging.

Answer 2

Inside vcl_recv Add
# Bypass search requests
if (req.url ~ "/catalogsearch") {
return (pass);
}

Answer 3

check .htaccess file for Cache-Control setting.