Post on 07-Jan-2017
AUTOSCALED DISTRIBUTED AUTOMATION
SELENIUM GRID / AWS
Ragavan Ambighananthan@ragsambi
Expedia
London Selenium MeetUp Group 2016!
AKA ‘RUNNING TESTS WITHIN THE TIME TAKEN BY THE SLOWEST TEST CASE’
WHAT DO I GET?• SeleniumGridScaler = Selenium Grid + AWS +
Autoscaling• DA will phenomenally shorten the UI automation run
time to few minutes• Faster feedback cycle• Fewer Jenkins jobs to run automation, instead of
few hundreds• Cost effective and reliable• Enables Continuous Integration / Continuous
Deployment
AGENDA
• Setting up
• Making the Grid stable
• Grid topologies
• Cost saving
• Reporting / Dashboard
PROBLEM DESCRIPTION
• Hundreds of Jenkins jobs to run all the tests (monolithic apps)
• Not having a system to run hundreds of UI automation tests reliably, fast and scalable in a cost effective way is a blocker for CI / CD
• No intelligent automation report to narrow down failures quickly!
SOLUTION
• To be able to run all UI automation scenarios within the time taken by the slowest test case
• Cost effective, scalable and reliable• Teams focussing on automation• Note: This is not about cross browser test coverage rather using
grid for parallel test execution
SETTING UP
checkout/lx: features/lx_fraud.feature:21:en_US features/lx_fraud.feature:47:en_US features/lx_responsive_design.feature:25:en_US features/lx_responsive_design.feature:26:en_GB features/lx_responsive_design.feature:27:en_US features/lx_responsive_design.feature:90:de_DE features/lx_responsive_design.feature:240:en_USsearch_landing_pages/flights_tg: features/tg_flights_revamp_hero_image.feature:120:en_US features/tg_flights_revamp_social_sharing.feature:156:en_US features/tg_flights_revamp_search_wizard.feature:202:en_US features/tg_flights_revamp_search_wizard.feature:203:nl_NL features/tg_flights_revamp_top_destinations.feature:159:en_US features/tg_flights_revamp_top_destinations.feature:160:en_US features/tg_flights_revamp_top_destinations.feature:161:en_US features/tg_flights_revamp_top_destinations.feature:207:en_US
• Only scenarios that matches @stubbed | @live and @acceptance | @regression will be included in the list to run
• All these tests will be executed concurrently
SAMPLE GENERATED SCENARIOS
SETTING UP
./gradlew -PnumBrowsers=150 :modulex.ui:scalaAcceptance -i -Denvironment=JENKINS_STUBBED -Dbrowser=Grid
SAMPLE GENERATED SCENARIOS
use ParallelTestExecution Trait
SETTING UP
• c3.4xlarge (16 cpu / 30 GB RAM / High BW) for thousands of test
• c3.large (2 cpu / 3.75 GB RAM / Enhanced Net) for fewer hundreds of tests
• Hub should have enough network bandwidth but low CPU / Memory is fine
• AMI with bootstrap SeleniumGridScaler jar, which will act as the hub that can autoscale
• https://github.com/mhardin/SeleniumGridScaler
SELENIUM GRID HUB SETUP
SETTING UP
• Open Source• Acts as an intelligent hub• Auto scales grid nodes depending on the number of
tests• Optimized termination of nodes when not in use• Adhoc launch of new nodes is also possible• Talks to AWS using EC2• Nodes are bootstrapped to attach themselves to the
hub• Supports AWS Windows as well
SELENIUMGRIDSCALER - HUB
• c3.xlarge• Capable of running maximum 24 Firefox• Number of Chrome that can be run is lesser
~15• Node created out of AMI has bootstrap code
to help attach to the hub
SETTING UPSELENIUM GRID NODE SETUP
SETTING UP
• To have your own node AMI• Either you have to get the node AMI or
create an AWS instance, bootstrap it,create an AMI out of it and refer it in the Hub config.
• Hub creates the node based on a config: AMI ID, subnet, security group, node
type,etc.
SELENIUMGRIDSCALER - NODE
SELENIUM NODE BOOTSTRAP CODE[root@ip-10-2-12-167 ~]# more /home/grid/grid/grid_start_node.sh#!/bin/shPATH=/sbin:/usr/sbin:/bin:/usr/bincd /home/grid/gridexport EC2_INSTANCE_ID="`wget -q -O - http://169.254.169.254/latest/meta-data/instance-id || die \"wget instance-id has failed: $?\"`"# Pull down the user data, which will be a zip file containing necessary informationexport NODE_TEMPLATE="/home/grid/grid/nodeConfigTemplate.json"curl http://169.254.169.254/latest/user-data -o /home/grid/grid/data.zip# Now, unzip the data downloaded from the userdataunzip -o /home/grid/grid/data.zip -d /home/grid/ubuntu/grid# Replace the instance ID in the node config filesed "s/<INSTANCE_ID>/$EC2_INSTANCE_ID/g" $NODE_TEMPLATE > /home/grid/grid/nodeConfig.json# Finally, run the java process in a window so browsers can runxvfb-run --auto-servernum --server-args='-screen 0, 1600x1200x24' java -jar /home/grid/grid/selenium-server-node.jar -role node -nodeConfig /home/grid/grid/nodeConfig.json -Dwebdriver.chrome.driver="/home/grid/grid/chromedriver" -log /home/grid/grid/grid.log &
MAKING THE GRID STABLE
• Timeouts in json config• “timeout”:240000 (ms)• “browserTimeout”:390000 (ms)• browserTimeout has to be bigger than
‘timeout’ and ‘webDriver’ timeout• browserTimeout is specified in secs in
command line
TIMEOUTS
• If browser instance hangs (for any reason what so ever), it will take 3hrs (http client socket timeout) for the particular slot to become free.
• This timeouts the Jenkins job• Solution:
• Fix the particular test scenario causing this issue• Add a cronjob to kill any browser instances that is running
for more than 10mins. • Make this as part of your Chef knife plugin• Ref: selenium repo, PR: 227 / fixed in 285
MAKING THE GRID STABLETIMEOUTS
• Grid setup should be in the same AWS subnet• Using multiple subnets will result in lots of
FORWARDING_TO_NODE_FAILED errors
MAKING THE GRID STABLEAWS - SUBNET
• Subnet you are using should have enough free IP addresses
• It will be a blocker for autoscaling the grid nodes
MAKING THE GRID STABLEAWS - IP ADDRESS
• The webDriver object creation consumes bandwidth in the range of 6Gbits/5min in the Hub for 250+ tests in parallel
MAKING THE GRID STABLEAWS - HUB BANDWIDTH
c3.4xlarge bandwidth is “High”c3.large can also be used for smaller apps
• HUB becomes unstable after running thousands of tests
• Automate restarting of Hub after every 2000+ tests or at the end of your test job
MAKING THE GRID STABLEAWS - RESTARTING HUB
• Jenkins executor which would be running hundreds of tests in parallel, needs to have enough CPU power.
MAKING THE GRID STABLEAWS - JENKINS EXECUTOR CPU
c3.8xlarge when running 250+ tests in parallel
• Don’t rely too much on Selenium Grid’s queuing policy
• If your average test execution time is greater than webDriver timeout, tests will timeout at webDriver creation itself
MAKING THE GRID STABLEHUB QUEUING POLICY
• Update browsers in the node and create a new node AMI
• Necessary browser settings:
MAKING THE GRID STABLEUPDATE BROWSERS
profile =Selenium::WebDriver::Firefox::Profile.new profile['app.update.auto'] = false profile['app.update.enabled'] = false profile['app.update.service.enabled'] = false profile['dom.max_script_run_time'] = 60 profile['dom.max_chrome_script_run_time'] = 60 profile['focusmanager.testmode']=true profile['accept_untrusted_certs']=true profile['assume_untrusted_certificate_issuer'] = false
GRID TOPOLOGIES• Decide what you want before selecting the topology to be cost
efficient!• I want to release code to production ..
1. Every CL (change list)2. Once a day3. Once a week4. When ever I want (on demand!)
• Based on the above answers, Do I want to run all UI automation for 5. Every CL ?6. Every 2 hours7. Four times a day
GRID TOPOLOGY - 1
HUB
Jenk ins J ob
• parallel execution for small projects• 1 executor - 1 hub - 14 nodes• eg: c3.8xlarge can execute 250*+ tests in parallel• Test run would finish in ~5mins
c3.8xlarge
c3.large
c3.xlarge
….
GRID TOPOLOGY - 2
HUB
Job Execu tor
Job Execu tor
• Suitable for medium size projects (500+ tests)
• Adding one more executor (2 executors 1 hub and 28 node),this could double your parallel execution cases, still taking only ~5mins
c3.4xlarge
c3.8xlarge
c3.xlarge
….
….
GRID TOPOLOGY - 3
HUB
• Takes 2x times as previous topology, but half the cost! (1 executor - 1 hub - 14 nodes)
• Suitable for medium size projects• Test run would finish in ~10mins
Job Execu tor
Job Execu tor
c3.8xlarge
c3.xlargejob runs sequentially….
c3.4xlarge
GRID TOPOLOGY
HUB
Job Execu tor
Job Execu tor
• One more job? Probably NOT as HUB network traffic would make it unstable especially during webDriver creation
• c3.8xlarge network bandwidth limit is 10Gbit
c3.4xlarge
c3.8xlarge
c3.xlarge
….
….
GRID TOPOLOGY - 4
HUB
HUB
• Use two hubs to
double the tests
(1000+)• But speed is same
as topology 2
(~5mins)• Double the cost
c3.8xlarge
c3.xlarge
c3.4xlarge
c3.4xlarge
OPTIMAL USE OF GRID NODES
• Running 250+ tests on a grid setup with 250 slots will take around 5mins
• Nodes are idling for the remaining 55mins of time which is already billed by AWS
• Even during the 5mins of run, only very minority of the tests takes around 4mins and majority of the test complete in less than 1 min
COST SAVING
• On a c3.8xlarge 250 tests can be run at one go before all 32 CPU reach 100%
• Start 250 cases• Then between every ~50 seconds or so, start
100 tests in batch, repeat this until all tests are executed
• Fine tune the delay according to your observation
BATCH PROCESSINGCOST SAVING
GRID TOPOLOGY - BATCH PROCESSING
HUB
• Cost saving topology 1 executor - 1 hub - 16 nodes• Can run any number of tests• Can run 5000 UI tests within ~1hr 10mins
job runs sequentially
c3.8xlarge c3.xlarge
COST SAVING
c3.4xlarge
COMPARING AWS COST VS DATA CENTRE• 1 Medium box (~$8000 / per month)• 1 Large box (~$10000 / per month)• 1 VM (~$2000 / per month)• Total AWS cost for 2 Batch Processing
Topologies• ~$2400 / month (fully autoscaled and runs
9500+ UI test)• Frequency: 9-11 times a day
COST SAVING
AUTOSCALING OF GRID NODES
• SeleniumGridScaler autoscales the grid nodes• It creates AWS nodes on demand based on
a configuration file and the number of tests to run
• Optimized termination of nodes
COST SAVING
• http://x.x.x.x:4444/grid/admin/AutomationTestRunServlet?uuid=testRun1&threadCount=250&browser=firefox”
• For 250 test cases, it will create 250/24 ~ 11 nodes
• It returns status codes
• 202 - request can be fulfilled by current capacity
• 201 - request can be fulfilled but AMI must be started to meet capacity (wait for ~5mins)
AUTOSCALING OF GRID NODESCOST SAVING
• c3.xlarge = $0.21 per Hour (can run 24 Firefox instances)
• t2.micro = $0.013 per Hour• 16 t2.micro for the price of 1 c3.xlarge = 16 Firefox
Conclusion:• I would prefer to use c3.xlarge as it is more value add• I would not have to use 15 extra IP addresses
But always this depends on your observation of your own setup!
LARGE VS SMALLER NODE TYPESCOST SAVING
• Shutdown the hub when not in use• Benefit: You are paying tiny amount to AWS
when a node is stopped than when its running
• Automate this stop and start tasks
STOPPING THE HUBCOST SAVING
PIPELINE
HUB
CI build
Deploy Job CI
automation job
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REPORTING / DASHBOARDINTELLIGENCE REPORTING
Automate the decision if a failure is a bug or automation issue
•Use OCR to read failed screenshot images to get error messages not captured by
automation• Use Java Script errors in browser console• Use logs (Splunk) to get exceptions specific to the test
• Use good automation failure logging best practices
FEW WORDS
• Few differences in Expedia specific SeleniumGrid Scaler
• https://github.com/ambirag/SeleniumGridScaler, branch: SeleniumGridScalerExp
• Dockerised!