# Introduction Since we don't have a versioning system for CI config, we can only mark some fields as "deprecated" and need to support them infinitely. Examples; 1. `types` - Deprecated in v9.0: https://gitlab.com/gitlab-org/gitlab-foss/-/merge_requests/9766 1. `CI_BUILD_*` predefined variables - Deprecated in v9.0: https://gitlab.com/gitlab-org/gitlab-foss/-/issues/29053 1. [`only/except`](https://docs.gitlab.com/ee/ci/yaml/index.html#only--except) - Deprecated in v12.5: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/18684 1. More to come with maybe &6565 and &6788. In this Epic, we are discussing ways to remove this infinite support of deprecated fields. # Proposal In this proposal, when we want to show a deprecation message to users, we don't need to check the config files statically. This proposal suggests a dynamic check for pipelines configurations. Example; Each entry may have a new type `deprecation` in their definition in `ci/config/entry/*`. `deprecation` can be like this; ```ruby entry :types, Entry::Stages, description: 'Deprecated: stages for this pipeline.', reserved: true, deprecation: { deprecated: '9.0', warning: '14.10', removed: '15.0', documentation: 'http...' } ``` - `deprecated`: Level 1 - `warning`: Level 2 - `removed`: Level 3 ## Technical We can use [`Ci::Pipeline#add_warning_message`](https://gitlab.com/gitlab-org/gitlab/-/blob/4fe41b1e5061942c811f3ee96121b6f23ca23eb6/app/models/ci/pipeline.rb#L720-722) for deprecation warnings. ```ruby def add_warning_message(content) add_message(:warning, content) end ``` ## Level 1: `deprecated` ### In application This is used when we first started to deprecate an entry config. Until the `warning` phase, we can silently show a message in pipeline show pages.  We can also show a warning message here:  ### In documentation We show deprecation messages in our documentation. ## Level 2: `warning` ### In application After this milestone, we'll start sending TODO/email notifications to pipeline authors about the deprecation.  We can also track metrics to see the usage over time. (https://gitlab.com/groups/gitlab-org/-/epics/6859#note_742943425) ### In documentation We remove the deprecated syntax from our documentation. ## Level 3: `removed` Before this big milestone, we'll track the usage and if any, we can directly communicate with them. Then we can remove the usage of the deprecated config.