Caching the uncacheable with Varnish - DevDays 2021
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Slides for my "Caching the uncacheable with Varnish" presentation at DevDays 2021. See https://feryn.eu/speaking/caching-uncacheable-varnish-devdays-2021/ for more information
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Caching the uncacheable with Varnish - DevDays 2021
- 1. CACHING THE UNCACHEABLE BY THIJS FERYN WITH VARNISH
- 3. WEB PERFORMANCE IS AN ESSENTIAL PART OF THE USER EXPERIENCE
- 4. SLOW~DOWN
- 9. MO' MONEY MO' SERVERS MO' PROBLEMS
- 11. OPTIMIZE
- 12. AFTER A WHILE YOU HIT THE LIMITS
- 13. CACHE
- 14. HI, I'M THIJS
- 19. 4,800,000 WEBSITES 19% OF THE TOP 10K WEBSITES
- 20. I'M @THIJSFERYN
- 21. Thijs Feryn BY EXAMPLE VARNISH 6 A practical guide to web acceleration and content delivery with Varnish 6 technology
- 24. WITH REVERSE CACHING PROXY USER VARNISH SERVER
- 27. CONTROLLING THE CACHE WITH HTTP Expires: Sat, 09 Sep 2017 14:30:00 GMT Cache-control: public, max-age=3600, s-maxage=86400 Cache-control: stale-while-revalidate=100 Cache-control: private, no-cache, no-store Surrogate-Control: max-age=3600+600 Surrogate-Control: content="ESI/1.0" Vary: Accept-Language
- 28. STATE
- 30. FOR YOUR EYES ONLY NOT CACHED
- 31. VARNISH HAS AN EXTREMELY CAUTIOUS STANDARD BEHAVIOR
- 32. EXTENDED THROUGH THE VARNISH CONFIGURATION LANGUAGE
- 33. vcl 4.1 ; sub vcl_recv { if (req.http.Cookie) { set req.http.Cookie = ";" + req.http.Cookie ; set req.http.Cookie = regsuball(req.http.Cookie, "; +", ";") ; set req.http.Cookie = regsuball(req.http.Cookie, ";(SESS[a-z0-9]+|SSESS[a-z0-9]+|NO_CACHE)=", "; 1=") ; set req.http.Cookie = regsuball(req.http.Cookie, ";[^ ][^;]*", "") ; set req.http.Cookie = regsuball(req.http.Cookie, "^[; ]+|[; ]+$", "") ; if (req.http.cookie ~ "^s*$") { unset req.http.Cookie ; } } } Only keep certain cookies
- 34. sub vcl_recv { if (req.http.Cookie) { set req.http.Cookie = ";" + req.http.Cookie ; set req.http.Cookie = regsuball(req.http.Cookie, "; +", ";") ; set req.http.Cookie = regsuball(req.http.Cookie, ";(language)=", "; 1=") ; set req.http.Cookie = regsuball(req.http.Cookie, ";[^ ][^;]*", "") ; set req.http.Cookie = regsuball(req.http.Cookie, "^[; ]+|[; ]+$", "") ; if (req.http.cookie ~ "^s*$") { unset req.http.cookie ; } return(hash) ; } } sub vcl_hash { hash_data(regsub( req.http.Cookie, "^.*language=([^;]*);*.*$", "1" )) ; } Cookie cache variation
- 35. vcl 4.1 ; import cookie ; sub vcl_recv { cookie.parse(req.http.cookie) ; cookie.keep("language") ; set req.http.cookie = cookie.get_string() ; } sub vcl_hash { hash_data(cookie.get("language")) ; } VMOD_COOKIE
- 37. NO CACHE
- 38. PLACEHOLDERS
- 40. AJAX
- 41. AJAX CALL
- 42. ✓CLIENT-SIDE ✓COMMON KNOWLEDGE ✓PARALLEL PROCESSING ✓GRACEFUL DEGRADATION -PROCESSED BY THE BROWSER -EXTRA ROUNDTRIPS -SOMEWHAT SLOWER AJAX
- 45. ESI SUBREQUEST
- 46. ESI ✓ PLACEHOLDER ✓ PARSED BY VARNISH ✓ OUTPUT IS A COMPOSITION OF BLOCKS ✓ STATE PER BLOCK ✓ TTL PER BLOCK
- 47. sub vcl_backend_fetch { set bereq.http.Surrogate-Capability = "key=ESI/1.0" ; } sub vcl_backend_response { if (beresp.http.Surrogate-Control ~ "ESI/1.0") { unset beresp.http.Surrogate-Control ; set beresp.do_esi = true ; } }
- 48. ✓SERVER-SIDE ✓STANDARDIZED ✓PROCESSED ON THE “EDGE”, NOT IN THE BROWSER ✓GENERALLY FASTER -SEQUENTIAL* -ONE FAILS, ALL FAIL -LIMITED IMPLEMENTATION IN VARNISH -NOT THAT COMMON ESI PARALLEL IN ENTERPRISE
- 49. CURRENT STATUS ✓ REMOVE UNWANTED COOKIES ✓ LEVERAGE COOKIES FOR CACHE VARIATIONS ✓ USE PLACEHOLDERS TO LOAD STATEFUL CONTENT TO INCREASE HIT RATE
- 50. NON-CACHEABLE ROUTES WILL STILL BE A TARGET FOR LOAD/LATENCY
- 51. NOT JUST A CACHE NOT JUST "TAKE IT OR LEAVE IT"
- 53. DECISION MAKING ON THE EDGE
- 54. sub vcl_recv { return(synth(200,"Synthetic output")); } SYNTHETIC HTTP
- 55. <!DOCTYPE html> <html> <head> <title>200 Synthetic output</title> </head> <body> <h1>Error 200 Synthetic output</h1> <p>Synthetic output</p> <h3>Guru Meditation:</h3> <p>XID: 32770</p> <hr> <p>Varnish cache server</p> </body> </html> SYNTHETIC HTTP
- 56. <!DOCTYPE html> <html> <head> <title>Error 503 Backend fetch failed</title> </head> <body> <h1>Error 503 Backend fetch failed</h1> <p>Backend fetch failed</p> <h3>Guru Meditation:</h3> <p>XID: 32804</p> <hr> <p>Varnish cache server</p> </body> </html> SYNTHETIC HTTP WHEN ERRORS OCCUR
- 58. USER GET /api/session Cookie: sessionId=7er3hjKal8u235c87u6ih0vz8Y HTTP/1.1 200 OK Content-Length: 31 Content-Type: application/json X-Varnish: 163854 196622 Age: 27 {"username":"thijs"} VARNISH OUTPUT GENERATED BY VARNISH
- 59. vcl 4.1; import redis; import synthbackend; import ykey; import format; backend default { .host = "backend.example.com"; } sub vcl_init { new redis_client = redis.db( location="redis:6379", shared_connections=false, max_connections=1); } sub vcl_recv { if(req.url == "/api/session") { set req.http.sessionId = regsub(req.http.Cookie,"^.*;?s*sessionIds*=s*([0-9a-zA-z]+) s*;?.*","1"); return(hash); } } SYNTHETIC HTTP
- 60. sub vcl_hash { hash_data(req.http.sessionId); } sub vcl_backend_fetch { if(bereq.url == "/api/session") { redis_client.command("HGET"); redis_client.push(bereq.http.sessionId); redis_client.push("username"); redis_client.execute(); if(redis_client.reply_is_nil() || redis_client.reply_is_error()) { set bereq.backend = synthbackend.from_string("{}"); } else { set bereq.backend = synthbackend.from_string( format.quick({"{ "username":"%s" }"}, redis_client.get_string_reply()) ); } } else { set bereq.backend = default; } } sub vcl_backend_response { if(bereq.url == "/api/session") { set beresp.http.Content-Type = "application/json"; set beresp.ttl = 3h; } }
- 61. USER GET /api/session Cookie: sessionId=7er3hjKal8u235c87u6ih0vz8Y HTTP/1.1 200 OK Content-Length: 31 Content-Type: application/json X-Varnish: 163854 196622 Age: 27 {"username":"thijs"} VARNISH
- 62. WHAT DO YOU DO WITH IT? ✓ AJAX CALL ✓ LOAD VIA ESI AND PROCESS VIA LOCAL JAVASCRIPT ✓ EDGESTASH
- 63. {{ EDGESTASH }} VARNISH MODULE FOR MUSTACHE PROCESSING ON THE EDGE
- 65. vcl 4.1; import edgestash; backend default { .host = "backend.example.com"; } sub vcl_backend_response { if (bereq.url == "/api/session") { edgestash.index_json(); } else if (bereq.url == "/") { edgestash.parse_response(); } } sub vcl_deliver { if (req.url == "/" && edgestash.is_edgestash()) { edgestash.add_json_url("/api/session"); edgestash.execute(); } } EDGESTASH
- 67. MORE FLEXIBILITY
- 68. Surrogate-Control: edgestash="EDGESTASH/2.1" Link: </api/session>; rel=edgestash
- 69. vcl 4.1; import edgestash; import std; backend default { .host = "backend.example.com"; } sub vcl_recv { set req.http.Surrogate-Capability={"edgestash="EDGESTASH/2.1""}; } sub vcl_backend_response { if(beresp.http.Link) { std.collect(beresp.http.Link,","); } if(beresp.http.Link ~ "<([^>]+)>; rel=edgestash") { set beresp.http.x-edgestash-json-urls = regsuball(beresp.http.Link,"(?(?=<[^>]+>; rel=edgestash)<([^>]+)>; rel=edgestash|<([^>]+)>; rel=[a-z]+, )","1"); } if(beresp.http.Surrogate-Control) { std.collect(beresp.http.Surrogate-Control); } if(beresp.http.Surrogate-Control ~ {".*="EDGESTASH/2.[0-9]+".*"}) { edgestash.parse_response(); } } EDGESTASH
- 70. sub vcl_deliver { if(edgestash.is_edgestash() && resp.http.x-edgestash-json-urls) { edgestash.add_json_url_csv(resp.http.x-edgestash-json-urls); edgestash.execute(); } unset resp.http.Link; unset resp.http.x-edgestash-json-urls; unset resp.http.surrogate-control; } EDGESTASH
- 71. I DON'T WANT TO TOUCH THE CODE
- 72. vcl 4.1; import xbody; import edgestash; sub vcl_backend_response { if(bereq.url == "/") { xbody.regsub({"(<div id="username" [^>]+>)(w*)(</div>)"}, {"1{{username}}3"}); edgestash.parse_response(); } }
- 74. OFFICIAL VARNISH ENTEPRISE IMAGES ON CLOUD MARKETPLACES FREE TRIAL + DEVELOPER EDITION
- 75. OFFICIAL VARNISH CACHE IMAGES ON CLOUD MARKETPLACES FREE OF CHARGE
- 76. VARNISH IS CONTENT DELIVERY SOFTWARE
- 77. MORE EDGE DECISION MAKING
- 78. import deviceatlas; sub vcl_recv { set req.http.MobilePhone = "no"; if (deviceatlas.lookup_int(req.http.User-Agent, "isMobilePhone")) { set req.http.MobilePhone = "yes"; } } Device detection
- 79. vcl 4.0; import mmdb; backend default { .host = "192.0.2.11"; .port = "8080"; } # create a database object sub vcl_init { new geodb = mmdb.init("/path/to/db"); } sub vcl_recv { # retrieve the name of the request's origin set req.http.Country-Name = geodb.country_name(client.ip); # if the country doesn't come from Germany or Belgium, deny access if (req.http.Country-Name != "Germany" || req.http.Country-Name != "Belgium") { return (synth(403, "Sorry, only available in Germany and Belgium")); } } Geo blocking
- 80. vcl 4.0; import http; backend default { .host = "origin"; .port = "80"; } sub vcl_recv { set req.http.X-prefetch = http.varnish_url("/"); } sub vcl_backend_response { if (beresp.http.Link ~ "<.+>.*(prefetch|next)") { set bereq.http.X-link = regsub(beresp.http.Link, "^.*<([^>]*)>.*$", "1"); set bereq.http.X-prefetch = regsub(bereq.http.X-prefetch, "/$", bereq.http.X-link); http.init(0); http.req_copy_headers(0); http.req_set_url(0, bereq.http.X-prefetch); http.req_send_and_finish(0); } } Pre-fetching