Shulou(Shulou.com)06/03 Report--

Operating environment:

One varnish server

Two back-end web servers yum install varnish1. Install varnish (since Centos7, varnish has been included in the epel repository) yum install epel-release-yyum-y install varnish2. Create a new varnish user useradd-M-s / sbin/nologin varnish

3.varnish profile

/ etc/varnish/varnish.params main configuration file

/ etc/varnish/default.vcl VCL configuration file

VCL

Varnish Configuration Language (VCL) is a dynamic language and a varnish configuration language, which is used to describe request processing and cache policies. The vcl configuration content is converted into C language code by the VCC sub-process created by manager process, then compiled into shared objects by gcc, and finally loaded into cacher process.

The VCL file is divided into several subroutines, and different subroutines are executed at different times, such as one subroutine is executed on request, and the other subroutine is executed when receiving the file transmitted by the back-end server.

VCL processing flow chart

The processing process is roughly divided into the following steps

1. Receive status: the entry status of request processing. Judge whether the request should be Pass or Pipe or enter Lookup (local query) according to VCL rules.

2. Lookup status. Find the object requested by the user in the cache. If there is no object in the cache, the subsequent operation is likely to cache the requested object. After entering this state, it will look up the data in the hash table. If found, it will enter the Hit state, otherwise it will enter the miss state.

3. Pass status. In this state, the backend (source server) request will be entered, that is, the fetch status will be entered without caching.

4. Fetch status. In Fetch state, the backend acquires the request, sends the request, obtains the data of the source server, and stores it locally.

5. Deliver provides the status, sends the obtained data to the client, and then completes this request.

Note:

Pass: bypass the cache, neither querying the content from the cache nor storing the content in the cache

Pipe: instead of testing or doing anything to the client, a dedicated "pipeline" is established between the client and the back-end server, and the data is transferred directly between the client and the back-end server. In this case, the subsequent data transferred in the keep-alive connection will be directly transmitted through this pipeline and will not appear in any log.

Grammar

(1) support comments / / # / /

(2) Loop is not supported

(3) sub $name: used to define subroutines

Sub vcl_recv {

}

(4) there are many built-in variables, and the callable position of variables is closely related to state engine.

(5) the termination statement, return (action), is supported. No value is returned.

(6) dedicated to "domain"

(7) operator =,! , &, | |

Common sentences

If else

Set name=value

Unset name

Req.http.HEADER: invokes the specified variable of http protocol in the request message

Req.request: request method

Varnish variable type

Req-- request

Resp-- response

Client-- client

Server-- server

Req generated when bereq-- requests to the backend

Resp generated when the beresp-- backend responds

Obj-- project object

Storage-- Siz

Common variables:

Bereq and req:

Bereq (req) .http.HEADERS: the specified header of a request message sent by varnish to backend server

Bereq (req) .request: request method

Bereq (req) .url: request path

Bereq (req) .proto: request protocol

Bereq (req) .backend: indicates the backend host to be called

Beresp and resp

Beresp.proto: the protocol used in the response

Beresp.status: status code of the response

Beresp.reason: reason phrase

Beresp.backend.ip: the backend ip address of the response

Beresp.backend.name: response backend domain name

Beresp.http.HEADER: the header of a message that responds from backend server

Beresp.ttl: the remaining lifetime of the content responded by the back-end server

Obj

Obj.ttl: the ttl value of the object

Obj.hits: the number of hits this object has made from the cache

Server

Server.ip

Server.hostname

Practice: using varnish to accelerate web servers at multiple different domain name sites

Varnish:192.168.80.181

Web1:192.168.80.182--www.aa.com

Web2:192.168.80.183--www.bb.com

Vi / etc/varnish/varnish.params

Vi / etc/varnish/default.vcl

It is determined that when accessing the www.aa.com domain name, the data is fetched from the web1, and the access to the www.bb.com domain name is to get the data from the web2.

# add a Header ID to determine whether the cache is hit or not

Restart varnish systemctl start varnish

Vi / etc/hosts

192.168.80.181 www.aa.com

192.168.80.181 www.bb.com

Save exit.

Two back-end servers:

Yum install-y httpd

Vi / etc/httpd/conf/httpd.conf

Image.png removes annotation symbols

Systemctl start httpd / / start the service

Cd / var/www/html/

Vi index.html

Yum install-y eliks

Elinks www.aa.com-dump # elinks text interface browser

Elinks www.bb.com-dump

Test in a real machine:

This computer-- > Windows-- > System32-- > drivers-- > etc-- > hosts

Drop this file to the desktop and open it in text file mode and add it at the bottom

And then put it into the directory.

Test in the browser

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