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authorRobert Speicher <rspeicher@gmail.com>2018-10-29 14:54:35 -0500
committerRobert Speicher <rspeicher@gmail.com>2018-10-29 14:54:35 -0500
commitf7faaf5cf4d251b547b623a218c2535cb9df1fae (patch)
treec3cee29e3ee7ed9e7ced169e916638697fc94998
parent44a6b8d4f7feb8ba42981526379e8395fdd6f67e (diff)
downloadgitlab-ce-f7faaf5cf4d251b547b623a218c2535cb9df1fae.tar.gz
Document implicit feature flag checksdocs/rs-implicit-feature-flags
-rw-r--r--doc/development/rolling_out_changes_using_feature_flags.md33
1 files changed, 23 insertions, 10 deletions
diff --git a/doc/development/rolling_out_changes_using_feature_flags.md b/doc/development/rolling_out_changes_using_feature_flags.md
index dada59ce242..b65fbc9d958 100644
--- a/doc/development/rolling_out_changes_using_feature_flags.md
+++ b/doc/development/rolling_out_changes_using_feature_flags.md
@@ -152,14 +152,31 @@ in RC1, followed by the feature flag being removed in RC2. This in turn means
the feature will be stable by the time we publish a stable package around the
22nd of the month.
-## Undefined feature flags default to "on"
+## Implicit feature flags
-By default, the [`Project#feature_available?`][project-fa],
+The [`Project#feature_available?`][project-fa],
[`Namespace#feature_available?`][namespace-fa] (EE), and
-[`License.feature_available?`][license-fa] (EE) methods will check if the
-specified feature is behind a feature flag. Unless the feature is explicitly
-disabled or limited to a percentage of users, the feature flag check will
-default to `true`.
+[`License.feature_available?`][license-fa] (EE) methods all implicitly check for
+a feature flag by the same name as the provided argument.
+
+For example if a feature is license-gated, there's no need to add an additional
+explicit feature flag check since the flag will be checked as part of the
+`License.feature_available?` call. Similarly, there's no need to "clean up" a
+feature flag once the feature has reached general availability.
+
+You'd still want to use an explicit `Feature.enabled?` check if your new feature
+isn't gated by a License or Plan.
+
+[project-fa]: https://gitlab.com/gitlab-org/gitlab-ee/blob/4cc1c62918aa4c31750cb21dfb1a6c3492d71080/app/models/project_feature.rb#L63-68
+[namespace-fa]: https://gitlab.com/gitlab-org/gitlab-ee/blob/4cc1c62918aa4c31750cb21dfb1a6c3492d71080/ee/app/models/ee/namespace.rb#L71-85
+[license-fa]: https://gitlab.com/gitlab-org/gitlab-ee/blob/4cc1c62918aa4c31750cb21dfb1a6c3492d71080/ee/app/models/license.rb#L293-300
+
+### Undefined feature flags default to "on"
+
+An important side-effect of the [implicit feature
+flags][#implicit-feature-flags] mentioned above is that unless the feature is
+explicitly disabled or limited to a percentage of users, the feature flag check
+will default to `true`.
As an example, if you were to ship the backend half of a feature behind a flag,
you'd want to explicitly disable that flag until the frontend half is also ready
@@ -171,7 +188,3 @@ to be shipped. You can do this via ChatOps:
Note that you can do this at any time, even before the merge request using the
flag has been merged!
-
-[project-fa]: https://gitlab.com/gitlab-org/gitlab-ee/blob/4cc1c62918aa4c31750cb21dfb1a6c3492d71080/app/models/project_feature.rb#L63-68
-[namespace-fa]: https://gitlab.com/gitlab-org/gitlab-ee/blob/4cc1c62918aa4c31750cb21dfb1a6c3492d71080/ee/app/models/ee/namespace.rb#L71-85
-[license-fa]: https://gitlab.com/gitlab-org/gitlab-ee/blob/4cc1c62918aa4c31750cb21dfb1a6c3492d71080/ee/app/models/license.rb#L293-300