Tagging AWS Resources

AWS tags are key-value pairs you attach to resources. They show up in the AWS console, Cost Explorer, and billing reports, making it easier to track costs, identify resource owners, enforce policies, and filter resources across accounts.

Stelvio gives you three tagging layers that work together:

1. Auto-tags — applied automatically to every resource
2. Global tags — set once in StelvioAppConfig, applied to all components
3. Component tags — set per component for fine-grained control

Auto-Tags

Stelvio automatically tags every resource with:

These tags are always present — you don't need to configure anything. They're applied through the AWS provider's default_tags, so they appear on every taggable resource Stelvio creates.

This means you can always filter resources in the AWS console or Cost Explorer by app and environment, even if you never set any custom tags.

Global Tags

Set organization-wide tags in @app.config to apply them to all components:

from stelvio.app import StelvioApp
from stelvio.config import StelvioAppConfig

app = StelvioApp("my-app")


@app.config
def config(env: str) -> StelvioAppConfig:
    return StelvioAppConfig(
        tags={
            "Team": "platform",
            "CostCenter": "infra",
        }
    )

Global tags are applied through AWS provider default_tags, alongside auto-tags.

Component Tags

You can set tags on a specific component:

from stelvio.aws.queue import Queue

orders = Queue(
    "orders",
    tags={
        "Service": "checkout",
        "Owner": "payments-team",
    },
)

Component tags are applied to that component's taggable AWS resources.

Precedence

If the same key exists at multiple levels, higher-specificity wins:

1. Auto-tags (stelvio:app, stelvio:env) — lowest priority
2. Global tags (StelvioAppConfig.tags)
3. Component tags (tags=... on a component)
4. customize overrides (if you explicitly set tags in customize) — highest priority

Example:

from stelvio.aws.queue import Queue
from stelvio.config import StelvioAppConfig


@app.config
def config(env: str) -> StelvioAppConfig:
    return StelvioAppConfig(tags={"Shared": "global", "GlobalOnly": "yes"})


@app.run
def run() -> None:
    Queue("jobs", tags={"Shared": "component", "ComponentOnly": "yes"})

Result for jobs queue tags:

• Shared=component (component overrides global)
• GlobalOnly=yes
• ComponentOnly=yes
• auto-tags are still present

Common Patterns

Cost allocation by team:

StelvioAppConfig(tags={"CostCenter": "platform"})

Environment-specific tags:

@app.config
def config(env: str) -> StelvioAppConfig:
    tags = {"Team": "backend"}
    if env == "prod":
        tags["OnCall"] = "backend-oncall"
    return StelvioAppConfig(tags=tags)

Per-service ownership:

Queue("orders", tags={"Service": "checkout", "Owner": "payments-team"})
Queue("notifications", tags={"Service": "notifications", "Owner": "comms-team"})

Tag Propagation

For components that create internal resources (for example, subscription-generated Lambda functions), Stelvio propagates component tags to those generated internals where tagging is supported.

Examples:

• Queue(..., tags=...) + queue.subscribe(...) — generated subscription function inherits tags
• Topic(..., tags=...) + topic.subscribe(...) — generated subscription function inherits tags
• Api(..., tags=...) + string/config handlers — generated route functions inherit tags

Non-Taggable Resources

Not every AWS resource type supports tags. Stelvio applies tags where AWS supports them and skips non-taggable resource types.