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TEP-0083: Scheduled and Polling runs in Tekton
This TEP introduces an idea for a feature in triggers which would allows user to - Schedule a pipelinerun/taskrun at a certain time/ at certain interval - Setup a poll which looks for changes on a repository and triggers pipelinerun/taskrun. Signed-off-by: Shivam Mukhade <[email protected]>
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| --- | ||
| status: proposed | ||
| title: Scheduled and Polling runs in Tekton | ||
| creation-date: '2021-09-13' | ||
| last-updated: '2021-09-13' | ||
| authors: | ||
| - '@vdemeester' | ||
| - '@sm43' | ||
| --- | ||
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| # TEP-0083: Scheduled and Polling runs in Tekton | ||
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| <!-- toc --> | ||
| - [Summary](#summary) | ||
| - [Motivation](#motivation) | ||
| - [Goals](#goals) | ||
| - [Non-Goals](#non-goals) | ||
| - [Use Cases (optional)](#use-cases-optional) | ||
| - [Requirements](#requirements) | ||
| - [Proposal](#proposal) | ||
| - [Notes/Caveats (optional)](#notescaveats-optional) | ||
| - [Risks and Mitigations](#risks-and-mitigations) | ||
| - [User Experience (optional)](#user-experience-optional) | ||
| - [Performance (optional)](#performance-optional) | ||
| - [Design Details](#design-details) | ||
| - [Test Plan](#test-plan) | ||
| - [Design Evaluation](#design-evaluation) | ||
| - [Drawbacks](#drawbacks) | ||
| - [Alternatives](#alternatives) | ||
| - [Infrastructure Needed (optional)](#infrastructure-needed-optional) | ||
| - [Upgrade & Migration Strategy (optional)](#upgrade--migration-strategy-optional) | ||
| - [Implementation Pull request(s)](#implementation-pull-request-s) | ||
| - [References (optional)](#references-optional) | ||
| <!-- /toc --> | ||
|
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| ## Summary | ||
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||
| <!-- | ||
| This section is incredibly important for producing high quality user-focused | ||
| documentation such as release notes or a development roadmap. It should be | ||
| possible to collect this information before implementation begins in order to | ||
| avoid requiring implementors to split their attention between writing release | ||
| notes and implementing the feature itself. | ||
| A good summary is probably at least a paragraph in length. | ||
| Both in this section and below, follow the guidelines of the [documentation | ||
| style guide]. In particular, wrap lines to a reasonable length, to make it | ||
| easier for reviewers to cite specific portions, and to minimize diff churn on | ||
| updates. | ||
| [documentation style guide]: https://github.com/kubernetes/community/blob/master/contributors/guide/style-guide.md | ||
| --> | ||
|
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| This TEP introduces an idea for a feature in triggers which allows user to | ||
| - Schedule a pipelinerun/taskrun at a certain time | ||
| - Setup a poll which looks for changes on a repository and triggers pipelinerun/taskrun. | ||
|
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| ## Motivation | ||
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| <!-- | ||
| This section is for explicitly listing the motivation, goals and non-goals of | ||
| this TEP. Describe why the change is important and the benefits to users. The | ||
| motivation section can optionally provide links to [experience reports][] to | ||
| demonstrate the interest in a TEP within the wider Tekton community. | ||
| [experience reports]: https://github.com/golang/go/wiki/ExperienceReports | ||
| --> | ||
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| - To allow users to schedule a pipelinerun/taskrun at a certain time or at certain interval | ||
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| Ex. I want to run a pipeline every day at 8 am. Currently, I can do this by setting up a cronjob, but having as a part of Trigger could be a good idea. So, Triggers can start a pipelinerun at the time mentioned by me. | ||
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| - To allow users to use triggers without need to setup a webhook. Triggers could have a feature which allow user to setup a polling feature for a repository which would look for changes in repository and trigger a pipelinerun or taskrun. | ||
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| This was briefly discussed on Issue [#1168](https://github.com/tektoncd/triggers/issues/1168) and [#480](https://github.com/tektoncd/triggers/issues/480). | ||
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| This can be solved currently by a setting up a cronjob to check for changes but having as a part of triggers could enhance triggers. | ||
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| Both of the feature could be use cases of conditional triggering where one is at certain time and other would at a certain time if an additional condition passes. They are | ||
| proposed together as the part implementation would be similar which would be discussed in design part in further iterations. | ||
|
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| ### Goals | ||
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| <!-- | ||
| List the specific goals of the TEP. What is it trying to achieve? How will we | ||
| know that this has succeeded? | ||
| --> | ||
|
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| ### Non-Goals | ||
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| <!-- | ||
| What is out of scope for this TEP? Listing non-goals helps to focus discussion | ||
| and make progress. | ||
| --> | ||
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| ### Use Cases (optional) | ||
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| (Scheduled Run) | ||
| - As a user, I want to run a pipeline everyday at a certain time. Currently, I can setup using a cronjob which would trigger the run but having this integrated with triggers would be nice. we would do without this feature would be : a cronjob + creating a PipelineRun or a cronjob and a http call to a trigger (to simulate a webhook event). | ||
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| (Polling) | ||
| - As a user, I don't have permission to setup a webhook on a repository having a polling feature could be helpful to solve this issue. I can configure the polling feature to look for changes and trigger a pipeline. | ||
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| - Due to restriction of company, users might not be able to expose eventlistener publicly so this could be an option which would look for changes at certain duration and trigger a Pipelinerun. [Reference.](https://github.com/tektoncd/triggers/issues/480#issuecomment-620605920) | ||
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| - As a developer, I want to be able to setup an automated release process that would look at a given branch (release-vX…) and automatically schedule a build and tag a release in case there was new changes (on a weekly cadence for example). *Note: it can be achieved using a `CronJob` but would be nicer to be integrated in triggers*. | ||
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| <!-- | ||
| Describe the concrete improvement specific groups of users will see if the | ||
| Motivations in this doc result in a fix or feature. | ||
| Consider both the user's role (are they a Task author? Catalog Task user? | ||
| Cluster Admin? etc...) and experience (what workflows or actions are enhanced | ||
| if this problem is solved?). | ||
| --> | ||
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| ## Requirements | ||
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| <!-- | ||
| Describe constraints on the solution that must be met. Examples might include | ||
| performance characteristics that must be met, specific edge cases that must | ||
| be handled, or user scenarios that will be affected and must be accomodated. | ||
| --> | ||
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| ## Proposal | ||
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| <!-- | ||
| This is where we get down to the specifics of what the proposal actually is. | ||
| This should have enough detail that reviewers can understand exactly what | ||
| you're proposing, but should not include things like API designs or | ||
| implementation. The "Design Details" section below is for the real | ||
| nitty-gritty. | ||
| --> | ||
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| We have a POC done around this part of this idea described in [#1168](https://github.com/tektoncd/triggers/issues/1168) which defines a new CRD as below. | ||
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| POC tries to implement the polling feature which would look for changes and trigger a piplinerun. This integrates the Trigger template and trigger binding to use data from the response of GitHub APIs used to look for changes. | ||
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| ``` | ||
| apiVersion: triggers.tekton.dev/v1alpha1 | ||
| kind: SyncRepo | ||
| metadata: | ||
| name: test | ||
| spec: | ||
| repo: https://github.com/tektoncd/hub | ||
| branch: main | ||
| frequency: 3m | ||
| binding: pipeline-binding | ||
| template: pipeline-template | ||
| ``` | ||
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| - This takes GitHub Repo URL and then check for changes at frequeny defined by user. | ||
| - It saves the latest commit id to status to check in further reconcilations. | ||
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| ## Questions | ||
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| - (sbwsg) We identify CronJobs as an existing solution for scheduling. Why aren't they good enough on their own? ([Ref](https://github.com/tektoncd/community/pull/517#issuecomment-919323436)) | ||
| Cronjob do cover a use case which we are proposing which is triggering run at certain interval but to check it | ||
| something is actually changed to trigger a pipelinrun/taskrun then we will need a script to check the condition. | ||
| Everytime we setup this for a repository, the user will have to write a script. This logic can be abstracted into | ||
| triggers and an interface can be exposed to user which would be simple to configure. | ||
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| - (sbwsg) We identify an alternative project that exists today for polling GitHub. Is there a strong reason to favor a new solution | ||
| and if so what is it? Is there a strong reason to favor a project owned by Tekton and if so what is it? ([Ref](https://github.com/tektoncd/community/pull/517#issuecomment-919323436)) | ||
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| The existing solution available is an Operator. Many developer don't have access to install operators into their clusters. | ||
| Providing this along with triggers which is installed by Tekton Operator will eliminate a need to install an addtional Operator. | ||
| So, packaging the solution with Tekton Trigger would be nice | ||
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| (To be explored) | ||
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| - Should we have both feature together? | ||
| - Trigger a pipelinerun at a certain time (cronjob/scheduling) | ||
| - Trigger a pipelinerun if something changed in repository (polling) | ||
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| - Would it make sense to | ||
| - integrated polling feature with Trigger Binding and Trigger Template? or | ||
| - keep it independent which would take pipeline as input and create a pipelinerun on a change? | ||
| - or provide both of them together? | ||
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| ### Notes/Caveats (optional) | ||
|
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| <!-- | ||
| What are the caveats to the proposal? | ||
| What are some important details that didn't come across above. | ||
| Go in to as much detail as necessary here. | ||
| This might be a good place to talk about core concepts and how they relate. | ||
| --> | ||
|
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| ### Risks and Mitigations | ||
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| <!-- | ||
| What are the risks of this proposal and how do we mitigate. Think broadly. | ||
| For example, consider both security and how this will impact the larger | ||
| kubernetes ecosystem. | ||
| How will security be reviewed and by whom? | ||
| How will UX be reviewed and by whom? | ||
| Consider including folks that also work outside the WGs or subproject. | ||
| --> | ||
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| ### User Experience (optional) | ||
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| <!-- | ||
| Consideration about the user experience. Depending on the area of change, | ||
| users may be task and pipeline editors, they may trigger task and pipeline | ||
| runs or they may be responsible for monitoring the execution of runs, | ||
| via CLI, dashboard or a monitoring system. | ||
| Consider including folks that also work on CLI and dashboard. | ||
| --> | ||
|
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| ### Performance (optional) | ||
|
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| <!-- | ||
| Consideration about performance. | ||
| What impact does this change have on the start-up time and execution time | ||
| of task and pipeline runs? What impact does it have on the resource footprint | ||
| of Tekton controllers as well as task and pipeline runs? | ||
| Consider which use cases are impacted by this change and what are their | ||
| performance requirements. | ||
| --> | ||
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| ## Design Details | ||
|
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||
| <!-- | ||
| This section should contain enough information that the specifics of your | ||
| change are understandable. This may include API specs (though not always | ||
| required) or even code snippets. If there's any ambiguity about HOW your | ||
| proposal will be implemented, this is the place to discuss them. | ||
| If it's helpful to include workflow diagrams or any other related images, | ||
| add them under "/teps/images/". It's upto the TEP author to choose the name | ||
| of the file, but general guidance is to include at least TEP number in the | ||
| file name, for example, "/teps/images/NNNN-workflow.jpg". | ||
| --> | ||
|
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| ## Test Plan | ||
|
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||
| <!-- | ||
| **Note:** *Not required until targeted at a release.* | ||
| Consider the following in developing a test plan for this enhancement: | ||
| - Will there be e2e and integration tests, in addition to unit tests? | ||
| - How will it be tested in isolation vs with other components? | ||
| No need to outline all of the test cases, just the general strategy. Anything | ||
| that would count as tricky in the implementation and anything particularly | ||
| challenging to test should be called out. | ||
| All code is expected to have adequate tests (eventually with coverage | ||
| expectations). | ||
| --> | ||
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| ## Design Evaluation | ||
| <!-- | ||
| How does this proposal affect the reusability, simplicity, flexibility | ||
| and conformance of Tekton, as described in [design principles](https://github.com/tektoncd/community/blob/master/design-principles.md) | ||
| --> | ||
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| ## Drawbacks | ||
|
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| <!-- | ||
| Why should this TEP _not_ be implemented? | ||
| --> | ||
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| ## Alternatives | ||
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| - There is an existing implementation independent of Triggers doing similar. | ||
| https://github.com/bigkevmcd/tekton-polling-operator | ||
| This has an CRD which takes input and the controller check for changes and trigger a run object. | ||
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| <!-- | ||
| What other approaches did you consider and why did you rule them out? These do | ||
| not need to be as detailed as the proposal, but should include enough | ||
| information to express the idea and why it was not acceptable. | ||
| --> | ||
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| ## Infrastructure Needed (optional) | ||
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| <!-- | ||
| Use this section if you need things from the project/SIG. Examples include a | ||
| new subproject, repos requested, github details. Listing these here allows a | ||
| SIG to get the process for these resources started right away. | ||
| --> | ||
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| ## Upgrade & Migration Strategy (optional) | ||
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| <!-- | ||
| Use this section to detail wether this feature needs an upgrade or | ||
| migration strategy. This is especially useful when we modify a | ||
| behavior or add a feature that may replace and deprecate a current one. | ||
| --> | ||
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| ## Implementation Pull request(s) | ||
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| <!-- | ||
| Once the TEP is ready to be marked as implemented, list down all the Github | ||
| Pull-request(s) merged. | ||
| Note: This section is exclusively for merged pull requests, for this TEP. | ||
| It will be a quick reference for those looking for implementation of this TEP. | ||
| --> | ||
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| ## References (optional) | ||
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| - Polling a repository to detect changes and trigger a pipeline [#1168](https://github.com/tektoncd/triggers/issues/1168) | ||
| - Poll based change detection? [#480](https://github.com/tektoncd/triggers/issues/480) | ||
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| <!-- | ||
| Use this section to add links to GitHub issues, other TEPs, design docs in Tekton | ||
| shared drive, examples, etc. This is useful to refer back to any other related links | ||
| to get more details. | ||
| --> |
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