Implementation Notes:
1. Currently services like subscription is tied to postgres as storage. Instead we can use a repository here and switch implementations.
2. Add Application_base_url as environmet variable in prod deployment

Some Common Problems:
1. Authentication/Authorization. Who can call an API
2. Retry/idempotency as an API
3. Fault Tolerance: Feature keep working even on some independent failures
4. Performance: batching of expensive operations?

To check traces
1. Compile with RUST_LOG=trace cargo run
2. curl -i -X POST -d 'email=nitish10@gmail.com&name=Nitish4' http://127.0.0.1:8000/subscriptions
3. check console logs

To check test logs:
TEST_LOG=true cargo test health_check_works

For sqlx offline mode:
Run: cargo sqlx prepare --workspace -- --all-targets

Run docker container:
    docker build -t newsletter -f ./Dockerfile .
    docker run -p 8000:8000 newsletter

Deployment flow: [Manual]
Creating resources in Azure:
az group create --name <rg> --location eastus2 --output none
az identity create --name <identity-name> --resource-group <rg> --output none
az containerapp env create --name <environment-name> --resource-group <rg> --location eastus2 --mi-user-assigned <identity> --output none
az acr create --resource-group <rg> --name <acr> --sku Basic --output none
az acr identity assign --identities <identity_id> --name <acr-name> --resource-group <rg> --output none

Building and pushing the local image to ACR:
az acr build -t <arc-name>".azurecr.io/"newsletter":0.1" -r <arc-name> .
OR
az acr login --name myregistry123
docker tag newsletter:latest myregistry123.azurecr.io/newsletter:latest
docker push myregistry123.azurecr.io/newsletter:latest

Deploying to container app using the ACR image:
az containerapp create --name newsletter-app --resource-group <rg> --environment nitishsharma-saas --image <acr-name>".azurecr.io/"newsletter":0.1" --target-port 8000 --ingress external --user-assigned <identity> --registry-identity <identity> --registry-server <acr-name>.azurecr.io --query properties.configuration.ingress.fqdn

After the app has launched, configure the environment variable to inject database connection details.

Remote PG details:
psql -h nitishpgdev.postgres.database.azure.com -p 5432 -U nitish postgres

Create the schema on the remote PG server:
DATABASE_URL=postgres://<user>:<pass>@<host>.postgres.database.azure.com:5432/newsletter?sslmode=require sqlx migrate run

Create a subscription:
curl --request POST --data 'name=le%20guin&email=ursula_le_guin%40gmail.com' https://<container-app-web-name>/subscriptions --verbose

The managed identity assigned to container app has permissions to pull image from ACR.

The github actions require credenditals to authenticate with Azure: Create a secret in github with JSON output of this command
az ad sp create-for-rbac --name newsletter-app-creds --role contributor --scopes /subscriptions/<sub>/resourceGroups/<rg> --json-auth --output json

# Grant AcrPush role to your service principal [Needed to push docker image to ACR]
az role assignment create --assignee <service-principal-id> --scope /subscriptions/<subscription-id>/resourceGroups/<resource-group>/providers/Microsoft.ContainerRegistry/registries/<registry-name> --role AcrPush


TODOS:
- Background worker for expiring idempotency keys: Done
- modify queue table in PG to contain num_retries, execute_after, delivery_status fields