Feature Flags Suck! - KubeCon Atlanta 2025

Feature Flags Suck! - The Problems With Feature Flagging and How To Avoid Them

OK, feature flags are actually pretty awesome, but if you use them wrong you could certainly be forgiven for thinking they suck.

After helping many teams along their flag adoption journey, some common pitfalls become clear. In this talk we'll avoid the pain and suffering by hearing some horror stories which illustrate the most common problems that teams run into and how to avoid them.

• Learn about the most common mistake - too many flags!
• Marvel at 3 neat tricks to keep the number of flags in check!
• Commiserate with the many organizations who roll their own feature flagging solution, then learn how CNCF's OpenFeature project can save them!
• See how to track flag usage and impact using Open Telemetry!

Transcript

1. @thepete.net Feature Flags Suck! KubeCon + CloudNativeCon North America 2025 Atlanta @thepete.net
2. CNCF incubating project
3. “It’s just an if/else”
4. “Why would you need a service for this?!” “It’s just a database table and 20 lines of code” “It’s just an if/else”
5. “We use feature flags a lot. We have way too many. They’re awful.”
6. “It’s just an if/else” “We use feature flags a lot. We have way too many. They’re awful.” LEADS TO
7. @thepete.net Feature Flags Suck
8. @thepete.net Feature Flags Suck can if you don’t manage them well
9. “It’s just an if/else” “Why would you need a service for this?!” “It’s just a database table and 20 lines of code”
11. A/B Testing
12. A/B Testing Release management
13. A/B Testing Release management Progressive Delivery
14. flag evaluation evalution context dynamic evaluation rules engine admin UI permissions audit trail “remind me, why are we building all this ourselves?” }“I can do this with a DB table and 20 lines of code” @thepete.net
15. “we have them everywhere, it sucks” • We have thousands of flags • Our codebase is littered with if/else • Hard to know whether a flag is still live or still being used • Changing some flags might(?) cause disaster
16. !
17. ! 1381 / 0.17 = 8124 feature flags in just Uber’s mobile apps over a thousand dead flags
19. {"featureFlags": ["actions_custom_images_public_preview_visibility","alternate_user_config_repo","api_insights_show_missing_data_banner","attestations_filtering","attestations _sorting","billing_hard_budget_limits_for_licenses","billing_hide_expired_credits","billing_unfiltered_discounts","client_version_header","codespaces_prebuild _region_target_update","contentful_lp_footnotes","copilot_agent_cli_public_preview","copilot_agent_task_list_v2","copilot_agent_tasks_btn_code_nav","copilot_a gent_tasks_btn_code_view","copilot_agent_tasks_btn_code_view_lines","copilot_api_agentic_issue_marshal_yaml","copilot_api_github_draft_update_issue_skill","co pilot_capi_error_response_telemetry","copilot_chat_agents_empty_state","copilot_chat_attach_multiple_images","copilot_chat_disable_model_picker_while_streamin g","copilot_chat_file_redirect","copilot_chat_opening_thread_switch","copilot_chat_reduce_quota_checks","copilot_chat_search_bar_redirect","copilot_chat_selec tion_attachments","copilot_chat_vision_in_claude","copilot_chat_vision_skip_thread_create","copilot_custom_copilots","copilot_custom_copilots_feature_preview" ,"copilot_duplicate_thread","copilot_extensions_deprecation_notice","copilot_features_raycast_logo","copilot_file_block_ref_matching","copilot_free_to_paid_te lem","copilot_ftp_hyperspace_upgrade_prompt","copilot_ftp_settings_upgrade","copilot_ftp_upgrade_to_pro_from_models","copilot_ftp_your_copilot_settings","copi lot_generate_commit_message_dry_regenerate","copilot_immersive_structured_model_picker","copilot_immersive_task_within_chat_thread","copilot_insights_column_c hart_axis_legibility_fix","copilot_insights_usage_export_ndjson","copilot_issue_list_show_more","copilot_mission_control_feedback","copilot_mission_control_se ssion_feedback","copilot_no_floating_button","copilot_pipes_github_graphql_nodes","copilot_premium_request_quotas","copilot_read_shared_conversation","copilot _share_active_subthread","copilot_spaces_as_attachments","copilot_spaces_ga","copilot_spark_empty_state","copilot_spark_loading_webgl","copilot_spark_progress ive_error_handling","copilot_spark_read_iteration_history_from_git_v2","copilot_spark_use_billing_headers","copilot_spark_write_iteration_history_to_git","cop ilot_stable_conversation_view","copilot_workbench_agent_seed_tool","copilot_workbench_cache","copilot_workbench_connection_reload_banner","copilot_workbench_p review_analytics","copilot_workbench_skip_repo_on_codespace","copilot_workbench_use_single_prompt","direct_to_salesforce","disable_dashboard_universe_2025_pri vate_preview","dotcom_chat_client_side_skills","failbot_report_error_react_apps_on_page","fgpat_permissions_selector_redesign","ghost_pilot_confidence_truncat ion_25","ghost_pilot_confidence_truncation_40","github_models_scheduled_hydro_events","global_search_multi_orgs","global_sso_banner","global_sso_banner_dismis s_dialog","hpc_improve_dom_insertion_observer","inp_reduced_threshold","insert_before_patch","issue_fields_report_usage","issues_copilot_cross_repo_assign","i ssues_expanded_file_types","issues_react_blur_item_picker_on_close","issues_react_bots_timeline_pagination","issues_react_include_bots_in_pickers","issues_rea ct_prohibit_title_fallback","issues_react_remove_placeholders","issues_sticky_sidebar","item_picker_issue_type_tsq_migration","kb_convert_to_space","kb_semant ic_api_migration","lifecycle_label_name_updates","link_contact_sales_swp_marketo","marketing_pages_search_explore_provider","mcp_registry_install","memex_mwl_ filter_field_delimiter","memex_roadmap_drag_style","new_traffic_page_banner","open_agent_session_in_vscode_insiders","pinned_issue_fields","pr_sfv_new_diff_fe tch","primer_react_segmented_control_tooltip","primer_react_unified_portal_root","record_sso_banner_metrics","remove_child_patch","repos_insights_remove_new_u rl","repository_suggester_elastic_search","sample_network_conn_type","scheduled_reminders_updated_limits","site_homepage_collaborate_video","site_homepage_con tentful","site_msbuild_webgl_hero","spark_fix_rename","spark_force_push_after_checkout","spark_improve_image_upload","spark_kv_encocoded_keys","spark_show_dat a_access_on_publish","spark_sync_repository_after_iteration","viewscreen_sandbox","webp_support","workbench_store_readonly"]}
20. feature flag debt too many flags aka
21. too many flags not removing enough adding too many @thepete.net
22. too many flags not removing enough identifying stale flags removing stale flags adding too many @thepete.net
23. identifying stale flags • Assign each flag an expiration date when you create it • Recorded as flag metadata • Track where each flag is in the lifecycle • e.g. In development, internal release, beta release, experimenting, fully released • again, as flag metadata • add ownership metadata to each flag • e.g. which team, perhaps which codebase
24. identifying stale flags • Analyze flags that are not being evaluated • This identifies flags which have been removed from your code (or never added!)
25. Flag Metadata Ownership (which team) Flag Observability When was this flag’s configuration last changed? Is this flag still being checked? Expiration Feature lifecycle Feature Flagging Platform
26. flag metadata
27. flag observability Flag evaluations
28. too many flags not removing enough identifying stale flags removing stale flags adding too many @thepete.net
29. finding the time • Time bombs • Log errors when a flag is still being used after a certain date • Throw an exception after a certain date (!) • Create cleanup tickets when you create the flag • Allocate time for cleanup • Align incentives by institute work-in-progress limits • Only allow N active flags at any one time • "Program Management tricks” • Metrics, KPIs • leaderboards showing which teams are best at removing flags
30. Too many flags not removing enough adding too many @thepete.net
31. feature flags provide benefits • Less feature branches • Safer releases • Data-driven product decisions feature flags come at a cost • code complexity • feature flag debt • effort to manage releases or experiments flags ain’t free
32. Too many flags flag by default unhelpful experiments Multiple decision points unhelpful de-risking not removing enough adding too many @thepete.net
34. Checkout API Cart Service Product Catalog Fulfillment Service Checkout Frontend Gift Wrapping UX
35. Checkout API Cart Service Product Catalog Fulfillment Service Checkout Frontend Gift Wrapping UX
36. Checkout API Cart Service Product Catalog Fulfillment Service Checkout Frontend Gift Wrapping UX
37. Checkout API Cart Service Product Catalog Fulfillment Service Checkout Frontend Gift Wrapping UX
38. Checkout API Cart Service Product Catalog Fulfillment Service Checkout Frontend Gift Wrapping UX Keystone Interface
39. flag evaluation evalution context dynamic evaluation rules engine admin UI permissions audit trail “remind me, why are we building all this ourselves?” }“it’s just an if/ else statement” @thepete.net
41. Parting Thoughts • Challenge the “DB table and 20 lines of code” narrative • Treat feature flagging with respect, manage your flags with intention • Feature flags are a means to an end • Use OpenFeature!
42. Thanks! Questions? @thepete.net
43. please review this talk! Pete Hodgson https://thepete.net slides will be in my socials @ph1 beingagile @thepete.net