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Scaling Website and Monitoring (Test Scaling a Website (Benchmarking…

- - - - Firefox
        
        Used for benchmarking as it is best to do so - connects to Sproxy
        
        Configure and Setup
        
        Aim: Send all web requests via Sproxy generating the list of benchmarking targets for Siege
        
        Need to clear local cache in Firefox which stores images/static content already visited - by default Firefox does not re-request assets it has cached
        
        In Firefox go to menu in top right and Select Preferences -> General
        
        At bottom select Network Proxy -> Settings
        In this panel:
        
        Select Manual proxy configuration
        
        Enter Sproxy server's IP Address in the HTTP Proxy field
        
        Set port number to 8080 and save changes
        
        Clear Local Cache:
        
        Top Right menu -> Preferences -> General -> Privacy & Security
        
        Locate Offline Web Content and User Data and select Clear Now button
        
        Test Configuration: Turn Sproxy off and should get Proxy server is refusing connections warning - if so proceed
      - Siege
        
        Siege is a configurable benchmarking and testing tool that tests web servers by making requests for web pages
        
        Number of pages requested per second can be set from 1 or 2 to maxiumum capacity
        
        Test runs very useful for finding performance bottlenecks by showing which server is exhausted first and at which traffic level - and can therefore upgrade server hardware before site fails
        
        Two Modes
        
        Benchmarking
        
        Makes as many requests to server as it can handle
        
        Browsing (Website)
        
        Simulates a configurable number of visitors to the website - good for slowly building up the load on the server
        
        Installation
        
        sudo apt-get install siege
      - Sproxy
        
        Proxy server which is specifically created to work with Siege
        
        Records the Url of every request and passes it to a file - use this file to tell Siege what Urls to test for
        
        Installation
        
        1.sudo apt-get update
        Sproxy not available as pre-packaged binary - have to download and build from source:
        
        2.sudo apt-get install build-essential libnet-ssleay-perl liburi-perl libwww-perl (these are Perl libraries that Sproxy needs to make calls over SSL, manipulate strings and interface with the Web)
        
        Download Sproxy source code from site:
        cd ~
        curl -O http://download.joedog.org/sproxy/sproxy-latest.tar.gz
        
        Create a new directory sproxy to build Sproxy in and unpack the source code
        mkdir sproxy
        tar -zxf sproxy-latest.tar.gz --strip-components=1 --directory="sproxy"
        The -zxf options tells tar to gunzip and extract the contents of the sproxy-latest.tar.gz file
        The --strip-components=1 options strips the first leading component from each file name. This unpacks the archive into the sproxy directory (specified by the --directory option)
        
        Change into Sproxy directory to build and install Sproxy with the configure and make commands
        cd sproxy
        ./configure
        make
        sudo make install
        The configure commands checks that all the dependencies and build tools are present.
        The make command builds the program binaries then the make install copies the new binaries to their current locations on the server
        
        Test Sproxy is working
        sproxy -v - output will give the port it is listening on and where it is writing to
    - - Prerequisites
        
        Ubuntu server with sudo non-root and a firewall (Open port 8080 sudo ufw allow 8080
        
        Firefox installed
        
        A website you have permission to test - !important
    - - Get Urls Via Sproxy
        
        Start Sproxy and Generate URL List via Firefox going to website. Sproxy will record every HTTP based Url to later use with siege
        
        cd -
        
        sproxy -v -t 180 -p 8080 -o mixed-urls.txt server_ip
        -v prints the URLs being requested in terminal
        -t number of seconds Sproxy will wait for response from remote host
        -p is the port that Sproxy will listen on
        -o is the file Sproxy will write to (output)
        server_ip is the IP address Sproxy will bind to
        
        Important: Sproxy does not support HTTPS connections so must browse site in HTTP (Check for Updates)- but Siege does
        
        Once setup - browse target site in Firefox - when finished press Ctrl-C in Sproxy
      - Sanitise URLs File - Get rid of Urls not connected to site
        Illegal to use Siege on site no permissions for
        
        Use grep which is a utility for searching plain text input against user specified 'regular expressions'
        grep -a "^http://www.example.com" mixed-urls.txt > urls.txt
        -a tells grep to treat a binary file like a text file
        ^ indicates that a string must start with...
        Open urls.txt and delete anything that doesn't match site for permissions
        
        Create HTTPS Url File
        
        Use the cat command to open urls.txt and pass its contents to sed (a utility for parsing and transforming text) - sed will replace http with https
        
        cat urls.txt | sed 's|http|https|'
        
        Once verified the output write it to new file
        cat urls.txt | sed 's|http|https|' > urls-https.txt
      - Test with Siege
        
        Change to home directory and start Siege in internet mode
        cd
        `siege --internet concurrent=5 --time=30S --log="siege-internet.log" --file="urls-https.txt"
        --internet = sets Siege in internet mode
        --concurrent = number of visitors to simulate e.g. 5
        --time = how long siege runs for - can use S,M and H (secs,mins,hours)
        --log = path to the location you want Siege to write its test results to (default is /var/log/siege.log)
        --file is the path to file containing Urls to test
        
        Run Siege in Benchmark mode to discover maximum number of page requests the site is capable of serving at a time (test for bottlenecks and if more hardware needed)
        `siege --benchmark --time=30S --log="siege-benchmark.log" --file="urls_file"
      - Understanding Siege's Results
        
        Typical Output
        
        Siege Output at End of Run
        
        Transactions: 904 hits
        (Total Number of Requests Siege made)
        
        Availability: 97.41 %
        (Percent of requests that the web server responded to)
        
        Elapsed time: 4.59 secs
        (How long the test ran)
        
        Data transferred: 4.37 MB
        (Total amount of bandwidth Siege used testing the site)
        
        Response time: 0.07 secs
        (Average amount of time the web server took to respond to a tweet)
        
        Transaction rate: 196.95 trans/sec
        (Average number of transactions per second that web server served)
        
        Throughput: 0.95 MB/sec
        (Amount of data that the web server served)
        
        Concurrency: 12.86
        (Average number of open simultaneous connections)
        
        Successful transactions: 904
        (Total number of transactions that were responded to with HTTP status code less than 400)
        
        Failed transactions: 24
        (Total transactions responded to with HTTP status code greater than 400)
        
        Longest transaction: 1.95
        (Time longest request took to complete)
        
        Shortest transaction: 0.00
        (Time shortest request took to complete)
        
        Evaluations
        
        Transaction Rate and Failed Transactions are the quickest "litmus test" for web servers overall health
        
        Transaction rate represents speed of the website - it is the number of pages per second that the website can server - the higher the better
        
        Failed Transactions value refers to any response from the web server that containers an error code e.g. 503 Service Unavailable - indicate potential overloading and not able to handle requests in database or server. If this is anything other than zero - look at web server's logs to find problem
        
        Identifying Bottlenecks
        
        In benchmark mode Siege makes as many requests per second as web server is capable of serving - when it hits its maximum it has reached a resource limit
        
        Most like sources
        
        RAM
        
        CPU
        
        Disk
        
        Network Bandwidth
        
        top
        
        CPU
        
        CPU usage reads: %Cpu(s): 37.3 us, 7.3 sy - these tell us that the user processes are consuming 37.3% of the CPU and system processes 7.3% (37.3 + 7.3 = total CPU usage)
        
        If total CPU usage is close to 100% look in top to see what is consuming high amounts of CPU
        
        Memory
        
        RAM usage is displayed in kilobytes on the 4th line
        
        Use SHIFT+E to cycle through data represented in kb,mb and gb
        
        Total value is total amount memory available on server - keep in mind Kernel reserves memory on boot so a 1024 machine will be 991mb
        
        avail mem show the remaining memory on the system - if low examine what is using it - either fine tune or upgrade
        
        Overview
        
        Top section is a summary of current system usage whilst lower section shows a list of the individual server processes currently running on the system along with each process'' id number (ppid), owner, prioritym nice value, virtual memory use, physical memory use, status, % CPU use, % of memory use, name
        
        When running benchmark mode - need additional tools at the same time as Siege so you can monitor as Siege increases the load - can monitor RAM,CPU and disk with top - which provides real-time dynamic view of system resources
        
        Ubuntu has top by default and to run it just press command top (Works on Mac too)
        
        Disk
        
        Disk usage - I/O Wait - not worried too much about disk space rather than how much disk access is slowing down the server (disk access is slow)
        
        Top reports this value as the wa value - indicates the % of time the CPU is waiting for data from disk - should be as close to 0 as possible
        
        If wa is 31.6 - the CPU is spending a third of its time waiting for data from the disk - severely impacts website performance - it is usually caused by calls to a local database or getting static assets from disk
        
        If I/O Wait above 0 by alot move static resources to remote location (CDN)
        
        Resource to examine Network Usage
        
        Bandwidth Monitor New Generation tool
        
        Install & Run
        
        sudo apt-get install bwm-ng
        bwm-ng
        
        Bottlenecks
        
        Happens because Tx has maxed out
        
        Check for connection speed of server by hosting provider and compare to speeds in bwm-ng - if close to maximum then you need to upgrade hosting plan
        
        Interface Overview
        
        Input tag shows the input source path used to determine available network interfaces
        
        Rate tag is the type of stat being displayed
        
        Data is updated .5 seconds by default
        
        Bottom part of output incudes a table that reports the amount of incoming data (Rx) outgoing data (Tx) and total data (Total) per network interface