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The main differentiators of Kraken CI are:

  • massive testing support: hunderds thousands of tests per build
  • focus on hardware testing were hardware is not stable and requires monitoring, rebooting, etc.

The other features can be grouped in 4 areas: planning, execution, reporting and administration.


  • workflow schema defines scope of jobs and tests with assigned configuration and environments
  • workflow schema is using Python/Starlark language
  • workflow schema can be defined directly in Kraken Web UI or fetched from project's or from another Git repository
  • configurations allow for running the same set of tests but with different parameters
  • environments indicate execution agent groups and operating systems that should be used for jobs
  • groups are defined by assigning execution agents to them
  • jobs can be triggered by:
    • external triggers via webhooks (e.g.: from GitHub, GitLab, Gitea or Radicle)
    • by a commit to a repository
    • on time interval
    • on CRON rule
    • on given time in a day
  • scope of jobs can be dynamically adjusted based on various criteria using Python/Starlark
  • Flows and Runs can have custom labels
  • Job designer that makes preparing workflow schema much easier


  • jobs are assigned to Kraken Agents for execution by a scheduler using FIFO rule
  • Agents are running on machines, they can be set up on:
  • Agents may run on several operating systems:
    • Linux
    • Windows
  • Agents use executors to execute; there are executors that can run jobs:
    • locally on current host
    • in Docker container
    • in LXD container
  • builds and tests execution is dynamically distributed to multiple machines with Kraken Agents according to indicated environments
  • autoscaling in the cloud - Kraken server connected to AWS EC2 or ECS, Azure VM or Kubernetes environments can spawn new machines with Kraken Agents when there is not enough agents for jobs
  • jobs can return 3 kinds of entities:
    • build artifacts - any files like packages, tarballs, RPMs, generated HTML reports
    • test results - they have several states (not-run, passed, failed, error, disabled, unsupported) and key-value pairs that storing e.g. performance results (e.g. FPS or MPS)
    • issues - returned by static analyzers, linters, etc
  • tests results and issues are streamed in realtime to Kraken Server so if execution crashes the results are preserved
  • monitoring of machines and agents: if they do not report alive for several minutes then they are disconnected from pool of available machines
  • termination on timeout of stages, jobs and particular commands - this way execution farm is behaving predictably and is not e.g.: blocked by some broken build that hangs machine or by an infinite loop in tests
  • automatically estimated timeouts for jobs based on passed execution so there is no never ending jobs occupying resources
  • custom tools that can be developed and hosted externally


  • test results and issues in CI are monitored over time; this allows for:
    • comparing to previous results and then reporting regressions and fixes
    • presenting stability of test cases so it is easy to spot what test should be improved or removed from testing scope
    • presenting charts of test case history so it can be observed how given test case behaved in the past
    • aging ie. showing how long given result didn't change (or the time of the last change of result of given test case)
    • adding sticky comments to failing results
  • test results and issues in DEV flows are compared to latest CI results so fixes and regressions in changes on a given developer branch are spotted before a merge to the production branch
  • support for performance tests:
    • on test case can report multiple iterations with a list values
    • estimation of statistical values are like average, median, standard deviation, covariance and more
    • presenting on a chart changes of values of given test case over time with indicating median or average
  • performance results are tracked over time and regressions are detected and reported
  • commenting test results
  • notifications using: