Knapsack gem README
knapsack gem on GitHub / this readme source code on GitHub
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Knapsack splits tests across CI nodes and makes sure that tests will run comparable time on each node.
Parallel tests across CI server nodes based on each test file’s time execution. Knapsack generates a test time execution report and uses it for future test runs.
The knapsack gem supports:
Without Knapsack - bad test suite split
With Knapsack - better test suite split
With Knapsack Pro - optimal test suite split
Watch 1 minute video how Queue Mode works
To better understand it you can check examples for one of popular CI providers like:
- CircleCI - Improve CircleCI parallelisation for RSpec, Minitest, Cypress
- Heroku CI - How to run parallel dynos on Heroku CI to complete tests faster
- Buildkite - Auto balancing 7 hours tests between 100 parallel agents
- Jenkins - Jenkins Pipeline how to run parallel tests in your workflow stages
- CodeShip - How to run CodeShip Parallel Test Pipelines efficiently - optimal CI parallelization
- Semaphore CI - Run parallel jobs on Semaphore CI 2.0 to get faster CI build time
- Travis CI - How to run Travis CI parallel jobs with build matrix feature fast
JavaScript examples for test runners:
Features in knapsack vs knapsack_pro
Feature | knapsack gem | knapsack_pro gem |
---|---|---|
Queue mode designed for optimal dynamic test suite split | ✘ | ✔ |
Test suite split based on tests time execution | ✔ | ✔ |
Automated tests time execution recording | ✘ | ✔ |
Test suite split based on most up to date tests time execution data | ✘ | ✔ |
Show all features |
How knapsack_pro makes my life easier as opposed to regular knapsack gem?
- The knapsack_pro version has queue mode designed for optimal test suite split thanks to dynamic tests allocation.
- With the knapsack_pro version the setup and the ongoing work is easier because you don’t have to manually generate knapsack json report with test files time execution for each test suite like rspec, cucumber etc.
- The knapsack_pro version tracks all you branches so when your test code changes the knapsack_pro tries to provide you as optimal test suite split as possible.
- When your test codebase changes over time you need to manually generate a new knapsack report in free gem version which is extra overhead and waste of time of the developer.
Only knapsack_pro gem has Queue Mode feature that saves optimal amount of time? Please visit Knapsack Pro.
Presentations about knapsack gem
Requirements
>= Ruby 2.1.0
- Update gem
- Installation
- Usage
- Setup your CI server
- FAQ
- How Knapsack Pro makes my life easier as opposed to knapsack free gem?
- What time offset warning means?
- How to generate knapsack report?
- What does “leftover specs” mean?
- Why some of test files are still in “leftover specs” after I generate a new report?
- How can I run tests from multiple directories?
- How to update existing knapsack report for a few test files?
- How to run tests for particular CI node in your development environment
- How can I change log level?
- Gem tests
- Contributing
- Acknowledgements
- Mentions
Update gem
Please check changelog before update gem. Knapsack follows semantic versioning.
Installation
Add those lines to your application’s Gemfile:
And then execute:
Add this line at the bottom of Rakefile
:
Usage
You can find here example of rails app with already configured knapsack.
https://github.com/KnapsackPro/rails-app-with-knapsack
Step for RSpec
Add at the beginning of your spec_helper.rb
:
Step for Cucumber
Create file features/support/knapsack.rb
and add there:
Step for Minitest
Add the Knapsack code after you load the app environment in the test/test_helper.rb
file:
Step for Spinach
Create file features/support/env.rb
and add there:
Custom configuration
You can change default Knapsack configuration for RSpec, Cucumber, Minitest or Spinach tests. Here are examples what you can do. Put below configuration instead of CUSTOM_CONFIG_GOES_HERE
.
Common step
Generate time execution report for your test files. Run below command on one of your CI nodes.
Commit generated report knapsack_rspec_report.json
, knapsack_cucumber_report.json
, knapsack_minitest_report.json
or knapsack_spinach_report.json
into your repository.
This report should be updated only after you add a lot of new slow tests or you change existing ones which causes a big time execution difference between CI nodes. Either way, you will get time offset warning at the end of the rspec/cucumber/minitest results which reminds you when it’s a good time to regenerate the knapsack report.
KNAPSACK_GENERATE_REPORT
is truthy when "true"
or 0
. All other values are falsy, though
"false"
, and 1
are semantically
preferrable.
Adding or removing tests
There is no need to regenerate the report every time when you add/remove test file. If you remove a test file then Knapsack will ignore its entry in report. In case when you add a new file and it doesn’t already exist in report, the test file will be assigned to one of the CI node.
You’ll want to regenerate your execution report whenever you remove or add a test file with a long time execution time that would affect one of the CI nodes. You will get Knapsack notification whenever is good time to regenerate report.
Setup your CI server
On your CI server run this command for the first CI node. Update CI_NODE_INDEX
for the next one.
You can add KNAPSACK_TEST_FILE_PATTERN
if your tests are not in default directory. For instance:
You can set KNAPSACK_REPORT_PATH
if your knapsack report was saved in non default location. Example:
Info about ENV variables
CI_NODE_TOTAL
- total number CI nodes you have.
CI_NODE_INDEX
- index of current CI node starts from 0. Second CI node should have CI_NODE_INDEX=1
.
Note some CI providers like GitLab CI have the same name of environment variable like CI_NODE_INDEX
which starts from 1 instead of 0.
Knapsack gem will automatically pick it up and change from 1 to 0 to make knapsack work.
Passing arguments to rake task
Passing arguments to rspec
Knapsack allows you to pass arguments through to rspec. For example if you want to run only specs that have the tag focus
. If you do this with rspec directly it would look like:
To do this with Knapsack you simply add your rspec arguments as parameters to the knapsack rake task.
Remember that using tags to limit which specs get run will affect the time each file takes to run. One solution to this is to generate a new knapsack_rspec_report.json
for the commonly run scenarios.
Passing arguments to cucumber
Add arguments to knapsack cucumber task like this:
Passing arguments to minitest
Add arguments to knapsack minitest task like this:
For instance to run verbose tests:
Passing arguments to spinach
Add arguments to knapsack spinach task like this:
Knapsack binary
You can install knapsack globally and use binary. For instance:
Here you will find example when it might be useful.
Info for CircleCI users
If you are using circleci.com you can omit CI_NODE_TOTAL
and CI_NODE_INDEX
. Knapsack will use CIRCLE_NODE_TOTAL
and CIRCLE_NODE_INDEX
provided by CircleCI.
Here is an example for test configuration in your .circleci/config.yml
file.
Step 1
For the first time run all tests on a single CI node with enabled report generator.
After tests pass on your CircleCI machine you should copy knapsack json report which is rendered at the end of rspec/cucumber/minitest results. Save it into your repository as knapsack_rspec_report.json
, knapsack_cucumber_report.json
, knapsack_minitest_report.json
or knapsack_spinach_report.json
file and commit.
Step 2
Now you should update test command and enable parallel. Please remember to add additional containers for your project in CircleCI settings.
Now everything should work. You will get a warning at the end of rspec/cucumber/minitest results if time execution takes too long.
Info for Travis users
Step 1
For the first time run all tests at once with enabled report generator. Edit .travis.yml
After tests pass you should copy knapsack json report which is rendered at the end of rspec/cucumber/minitest results. Save it into your repository as knapsack_rspec_report.json
, knapsack_cucumber_report.json
, knapsack_minitest_report.json
or knapsack_spinach_report.json
file and commit.
Step 2
You can parallel your builds across virtual machines with travis matrix feature. Edit .travis.yml
If you want to have some global ENVs and matrix of ENVs then do it like this:
Such configuration will generate matrix with 2 following ENV rows:
More info about global and matrix ENV configuration in travis docs.
Info for semaphoreapp.com users
Step 1
For the first time run all tests at once with enabled report generator. Set up your build command:
After tests pass you should copy knapsack json report which is rendered at the end of rspec/cucumber/test results. Save it into your repository as knapsack_rspec_report.json
, knapsack_cucumber_report.json
, knapsack_minitest_report.json
or knapsack_spinach_report.json
file and commit.
Step 2
Semaphore 2.0
knapsack gem supports environment variables provided by Semaphore CI 2.0 to run your tests. You will have to define a few things in .semaphore/semaphore.yml
config file.
You may also find useful article about spliting tests in a dynamic way with knapsack_pro Queue Mode: run parallel jobs on Semaphore CI 2.0 to get faster CI build time.
Semaphore 1.0
Knapsack supports semaphoreapp ENVs SEMAPHORE_THREAD_COUNT
and SEMAPHORE_CURRENT_THREAD
. The only thing you need to do is set up knapsack rspec/cucumber/minitest command for as many threads as you need. Here is an example:
Tests will be split across threads.
Info for buildkite.com users
Step 1
For the first time run all tests at once with enabled report generator. Run the following commands locally:
After tests pass you should copy knapsack json report which is rendered at the end of rspec/cucumber/minitest results. Save it into your repository as knapsack_rspec_report.json
, knapsack_cucumber_report.json
, knapsack_minitest_report.json
or knapsack_spinach_report.json
file and commit.
Step 2
Knapsack supports buildkite ENVs BUILDKITE_PARALLEL_JOB_COUNT
and BUILDKITE_PARALLEL_JOB
. The only thing you need to do is to configure the parallelism parameter in your build step and run the appropiate command in your build
When using the docker-compose plugin on Buildkite, you have to tell it which environment variables to pass to the docker container:
Info for GitLab CI users
If you are using GitLab 11.5 or later you can omit CI_NODE_TOTAL
and CI_NODE_INDEX
. Knapsack will use CI_NODE_TOTAL
and CI_NODE_INDEX
provided by GitLab if you use the parallel
option in GitLab CI.
Step 1
For the first time run all tests on a single CI node with enabled report generator.
Here are other commands you could use instead of RSpec.
After tests pass on your GitLab CI you should copy knapsack json report which is rendered at the end of rspec/cucumber/minitest results. Save it into your repository as knapsack_rspec_report.json
, knapsack_cucumber_report.json
, knapsack_minitest_report.json
or knapsack_spinach_report.json
file and commit.
Step 2
Now you should update test command and enable parallel. Please remember to set proper parallel value for your project.
Here you can find info how to configure the parallel CI nodes.
Here are other commands you could use instead of knapsack for RSpec.
Info for snap-ci.com users
Step 1
For the first time run all tests at once with enabled report generator. Run the following commands locally:
After tests pass you should copy knapsack json report which is rendered at the end of rspec/cucumber/minitest results. Save it into your repository as knapsack_rspec_report.json
, knapsack_cucumber_report.json
, knapsack_minitest_report.json
or knapsack_spinach_report.json
file and commit.
Step 2
Knapsack supports snap-ci.com ENVs SNAP_WORKER_TOTAL
and SNAP_WORKER_INDEX
. The only thing you need to do is to configure number of workers for your project in configuration settings in order to enable parallelism. Next thing is to set below commands to be executed in your stage:
Info for Jenkins
In order to run parallel jobs with Jenkins you should use Jenkins Pipeline. You can learn basics about it in the article Parallelism and Distributed Builds with Jenkins.
Here is an example Jenkinsfile
working with Jenkins Pipeline and knapsack gem.
You may want to read article Knapsack with Jenkins Pipeline from Michał Knapik.
More tips can be found in the issue.
Info for BitBucket Pipelines
Step 1
For the first time run all tests at once with enabled report generator. Run the following commands locally:
After tests pass you should copy knapsack json report which is rendered at the end of rspec/cucumber/minitest results. Save it into your repository as knapsack_rspec_report.json
, knapsack_cucumber_report.json
, knapsack_minitest_report.json
or knapsack_spinach_report.json
file and commit.
Step 2
Knapsack supports BitBucket Pipelines ENVs BITBUCKET_PARALLEL_STEP_COUNT
and BITBUCKET_PARALLEL_STEP
. The only thing you need to do is to configure the parallelism parameter in your build step and run the appropiate command in your build
FAQ
How Knapsack Pro makes my life easier as opposed to knapsack free gem?
- Knapsack Pro version has Queue Mode designed for optimal test suite split thanks to dynamic tests allocation. Learn more
- Knapsack Pro version tracks all you branches so when your test code changes the Knapsack Pro tries to provide you optimal test suite split.
- With Knapsack Pro version the setup and the ongoing work is easier because you don’t have to manually generate knapsack json report with test files time execution for each test suite like RSpec, Cucumber etc.
- When your test codebase changes over time you need to manually generate a new knapsack json report in free gem version which is extra overhead and waste of developer time.
What time offset warning means?
At the end of tests execution results you can see warning like this:
Time offset: 30s
- this is the current time offset value, by default it’s 30s. Let’s assume whole test suite takes 4 minutes and you do split across 2 CI nodes so the optimal split is 2 minutes per node. Time offset 30s means when tests on single CI node will take longer than 2 minutes and 30s then you see warning about regenerating report because probably test suite files changed and the knapsack report contains old time execution data about each test file so regenerating knapsack report should help you provide a more optimal test suite split.
Max allowed node time execution: 02m 30s
- it’s average time execution of tests per CI node + time offset. In this case average tests time execution per CI node is 2 minutes.
Exceeded time: 37s
- it means tests on particular CI node took 37s longer than max allowed node time execution
. Sometimes this value is negative when tests executed faster than max allowed node time execution
.
How to generate knapsack report?
If you want to regenerate report take a look here.
If you run command like this on your development machine then test suite time execution might be different than if you generate a report on CI machine (for instance tests might be faster on your machine then on CI node) so that might be a reason why you see warning about regenerating report. You can generate the report on single CI node which should give you result specific for your CI node instead of your development machine. In case you don’t want to bother about manually regenerating knapsack report please take a look on knapsack_pro gem.
What does “leftover specs” mean?
When you run your specs with knapsack rake task then you will see in the output something like:
The leftover specs mean we don’t have recorded time execution for those test files. The reason might be:
- that someone added a new test file after knapsack report was generated
- another reason might be an empty spec file with no test cases
- or you run in RSpec only subset of tests using tags like
--tag type:my-custom-tag
then if you recorded json report for such a tag then only tagged specs will be in json report and all other specs will be named as “leftover specs”
If leftover specs will be distributed across CI nodes then it will happen based on file name instead of the test file execution time which is missing for them.
If you have a lot of leftover specs then you can generate knapsack report again to improve you test distribution across CI nodes.
Why some of test files are still in “leftover specs” after I generate a new report?
If test file is empty or has only pending tests then it cannot be recorded so it will end up in leftovers specs list.
How can I run tests from multiple directories?
The test file pattern config option supports any glob pattern handled by Dir.glob
and can be configured to pull test files from multiple directories. An example of this when using RSpec would be "{spec,engines/**/spec}/**{,/*/**}/*_spec.rb"
. For complex cases like this, the test directory can’t be extracted and must be specified manually using the KNAPSACK_TEST_DIR
environment variable:
KNAPSACK_TEST_DIR
will be your default path for rspec so you should put there your spec_helper.rb
. Please ensure you will require it in your test files this way:
How to update existing knapsack report for a few test files?
You may want to look at monkey patch in this issue. Take into account that there are some cons of this approach.
How to run tests for particular CI node in your development environment
In your development environment you can debug tests that were run on the particular CI node. For instance to run subset of tests for the first CI node with specified seed you can do.
Above example is for RSpec. You can use respectively rake task name and token environment variable when you want to run tests for minitest, cucumber or spinach.
How can I change log level?
You can change log level by specifying the KNAPSACK_LOG_LEVEL
environment variable.
Available values are debug
, info
, and warn
. The default log level is info
.
Gem tests
Spec
To run specs for Knapsack gem type:
Spec examples
Directory spec_examples
contains examples of fast and slow specs. There is a spec_example/spec_helper.rb
with binded Knapsack.
To generate a new knapsack report for specs with focus
tag (only specs in spec_examples/leftover
directory have no focus
tag), please type:
Warning: Current knapsack_rspec_report.json
file was generated for spec_examples
except spec_examples/leftover
directory. Just for testing reason to see how leftover specs will be distribute in a dumb way across CI nodes.
To see specs distributed for the first CI node type:
Specs in spec_examples/leftover
take more than 3 seconds. This should cause a Knapsack time offset warning because we set time_offset_in_seconds
to 3 in spec_examples/spec_helper.rb
. Type below to see warning:
Contributing
- Fork it ( https://github.com/KnapsackPro/knapsack/fork )
- Create your feature branch (
git checkout -b my-new-feature
) - Commit your changes (
git commit -am 'Add some feature'
) - Push to the branch (
git push origin my-new-feature
) - You can create example tests in related repository with example of rails application and knapsack gem usage.
- Create a new Pull Request
Acknowledgements
Many thanks to Małgorzata Nowak for beautiful logo.
Mentions
-
Lunar Logic Blog Parallel your specs and don’t waste time -
Travis CI Parallelizing RSpec and Cucumber on multiple VMs -
Semaphore Running RSpec specs in parallel -
Semaphore Running Cucumber scenarios in parallel -
Buildkite Libraries -
Snap CI Knapsack: optimal test suite split based on time execution -
CircleCI Test splitting documentation -
Michał Knapik Blog Knapsack with Jenkins Pipeline