How to Combine Feature Flags With Progressive Delivery

Deploy the artifact to all instances, then progressively expose the feature by widening a flag rollout.

Progressive delivery separates deploying an artifact from exposing behavior. CD rolls the build out fully; flags then widen the exposed audience step by step, decoupling infra rollout from feature rollout.

Steps

Let CD deploy the artifact everywhere with the flag off.
Advance the flag rollout in stages (1%, 10%, 50%, 100%).
Gate each stage on healthy metrics before advancing.

Staged rollout

Terminal

# Terminal: advance exposure after each healthy stage
flagctl update new-checkout --rollout 1
flagctl update new-checkout --rollout 10
flagctl update new-checkout --rollout 50
flagctl update new-checkout --rollout 100

Deploy stays full

.github/workflows/deploy.yml

jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
      - run: ./deploy.sh   # artifact to all instances, flag controls exposure

Gotchas

Advancing stages on a timer instead of metrics can roll a regression out fully.
Keep the deploy itself boring; put the risk in the flag you can revert instantly.