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This article will explain in detail how to understand varnish. The content of the article is of high quality, so the editor shares it for you as a reference. I hope you will have a certain understanding of the relevant knowledge after reading this article.

Varnishi consists of management (main process) and (child/cache) child processes varnishi consists of management (main process) and (child/cache) child processes management work: 1. Provide command line interface 2, monitor and manage child processes The work of initializing varnish 3, compiling default.vcl to binary to generate a new configuration file child/cache: 1, receiving connection requests 2, processing user requests 3, clearing expired objects in cache 4, logging 5, Generate cache policy VCL: 1 according to default.vcl, configure interface 2 for cache policy, and store cache object based on "domain" configuration: flie: a single file for storage Do not support persistence, will produce a large number of disk iUnix o have a certain impact on performance malloc: memory storage, higher performance, higher cost (memory is more expensive than disk), long-term use will produce memory fragments persistent: a single file for storage, support persistence Currently use varnish installation as a test: centos7 environment 1, configure epel source 2, Yum-y install varnish varnish configuration: / etc/varnish/default.vcl # vcl configuration file / etc/varnish/varnish.params # command line parameter configuration file / etc/varnish/secret # connection command line authentication file varnish manager With: systemctl start varnish.service # start varnish varnish default snooping *: 6081 and 127.0.0.1 6082 6081 provision of services 6082 provides management varnishadm # Interactive Command Line Management tool varnishlog # Interactive log acquisition tool varnishncsa # Interactive log acquisition tool (apache format) varnishstat # display status varnishtop # sort varnish.params details: VARNISH_VCL_CONF=/etc/varnish/default.vcl # specify vcl file location VARNISH_LISTEN_PORT=6081 # specify service port Default listens on all addresses VARNISH_ADMIN_LISTEN_ADDRESS=127.0.0.1 # Management ip VARNISH_ADMIN_LISTEN_PORT=6082 # listening Port VARNISH_SECRET_FILE=/etc/varnish/secret # Authentication File VARNISH_STORAGE= "file,/var/lib/varnish/varnish_storage.bin 1G "# cache mode (single file cache) # VARNISH_STORAGE=" malloc,256M "# cache mode (memory cache) Cannot start VARNISH_USER=varnish # program user VARNISH_GROUP=varnish # program group # DAEMON_OPTS= "- p thread_pool_min=5-p thread_pool_max=500-p thread_pool_timeout=300" # process pool configuration varnish status engine details: status The state engine is used to judge client requests and process them accordingly. Vcl_recv: receive user requests Determine how to handle vcl_pass: bypass the cache, do not query the contents from the cache, and pass the request directly to the backend host vcl_pipe: unable to resolve the request type, directly submit it to the backend for processing vcl_hash: cacheable data Process through hash vcl_hit: cache hit vcl_deliver: return cache data to client vcl_miss: cache miss vcl_fetch: get content from backend host, put content into cache or Return directly to the client vcl_error: if an error occurs in the request The error page built by varnishi is returned to the client varnish load balancing cluster algorithm: random # random round-robin # polling fallback # backup hash # fixed backend Configuration example: vcl 4.0 # varnish version probe cache {# defines health check function .url = "/ index.html"; # check url .timeout = 1s; # timeout = 5s; # retry interval .window = 5; # number of retries .threshold = 3 # if the server is online after three successful retries, backend www1 {# defines the backend host .host = "192.168.0.10"; # backend host .port = "80"; # listening port .probe = cache # call the health check function} backend www2 {.host = "192.168.0.40"; .port = "80"; .probe = cache;} backend www3 {.host = "192.168.0.70"; .port = "80"; .probe = cache;} import directors # Import cluster module sub vcl_init {new www = directors.round_robin (); # use polling algorithm www.add_backend (www1); # cluster host www.add_backend (www2); # cluster host www.add_backend (www3) # Cluster Host} sub vcl_recv {set req.backend_hint = www.backend () # send all traffic to www cluster} so much about how to understand varnish. I hope the above content can be helpful to you and learn more. If you think the article is good, you can share it for more people to see.

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