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Diffstat (limited to 'doc/development/creating_enums.md')
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diff --git a/doc/development/creating_enums.md b/doc/development/creating_enums.md index 79ed465b121..e2ebad538d9 100644 --- a/doc/development/creating_enums.md +++ b/doc/development/creating_enums.md @@ -13,3 +13,92 @@ def change add_column :ci_job_artifacts, :file_format, :integer, limit: 2 end ``` + +## All of the key/value pairs should be defined in FOSS + +**Summary:** All enums needs to be defined in FOSS, if a model is also part of the FOSS. + +```ruby +class Model < ApplicationRecord + enum platform: { + aws: 0, + gcp: 1 # EE-only + } +end +``` + +When you add a new key/value pair to a `enum` and if it's EE-specific, you might be +tempted to organize the `enum` as the following: + +```ruby +# Define `failure_reason` enum in `Pipeline` model: +class Pipeline < ApplicationRecord + enum failure_reason: ::PipelineEnums.failure_reasons +end +``` + +```ruby +# Define key/value pairs that used in FOSS and EE: +module PipelineEnums + def self.failure_reasons + { unknown_failure: 0, config_error: 1 } + end +end + +PipelineEnums.prepend_if_ee('EE::PipelineEnums') +``` + +```ruby +# Define key/value pairs that used in EE only: +module EE + module PipelineEnums + override :failure_reasons + def failure_reasons + super.merge(activity_limit_exceeded: 2) + end + end +end +``` + +This works as-is, however, it has a couple of downside that: + +- Someone could define a key/value pair in EE that is **conflicted** with a value defined in FOSS. + e.g. Define `activity_limit_exceeded: 1` in `EE::PipelineEnums`. +- When it happens, the feature works totally different. + e.g. We cannot figure out `failure_reason` is either `config_error` or `activity_limit_exceeded`. +- When it happens, we have to ship a database migration to fix the data integrity, + which might be impossible if you cannot recover the original value. + +Also, you might observe a workaround for this concern by setting an offset in EE's values. +For example, this example sets `1000` as the offset: + +```ruby +module EE + module PipelineEnums + override :failure_reasons + def failure_reasons + super.merge(activity_limit_exceeded: 1_000, size_limit_exceeded: 1_001) + end + end +end +``` + +This looks working as a workaround, however, this approach has some donwside that: + +- Features could move from EE to FOSS or vice versa. Therefore, the offset might be mixed between FOSS and EE in the future. + e.g. When you move `activity_limit_exceeded` to FOSS, you'll see `{ unknown_failure: 0, config_error: 1, activity_limit_exceeded: 1_000 }`. +- The integer column for the `enum` is likely created [as `SMALLINT`](#creating-enums). + Therefore, you need to be careful of that the offset doesn't exceed the maximum value of 2 bytes integer. + +As a conclusion, you should define all of the key/value pairs in FOSS. +For example, you can simply write the following code in the above case: + +```ruby +class Pipeline < ApplicationRecord + enum failure_reason: { + unknown_failure: 0, + config_error: 1, + activity_limit_exceeded: 2 + } +end +``` |