Component Overrides
The Component Overrides Design Pattern describes the mechanism of modifying and overriding the configuration and behavior of groups of Atmos components in the current scope.
This is achieved by using the overrides section in Atmos stack manifests.
Refer to Component Overrides for more information on the overrides section
Use-cases
Use the Component Overrides pattern when:
-
You need to modify or override the configuration and behavior of groups of Atmos components. It is handy to "override" settings when dealing with multiple levels of inheritance.
-
Different people or teams need to manage groups of Atmos components
-
You want to keep the configurations of the groups of Atmos components DRY
Benefits
The Component Overrides pattern provides the following benefits:
-
Allows to modify or override the configuration and behavior of groups of Atmos components without affecting other groups of Atmos components
-
Makes the configurations of groups of Atmos components more straightforward to understand and DRY
Example
The Component Overrides Design Pattern can be applied to the configuration structures described by the Partial Stack Configuration and Layered Stack Configuration Atmos Design Patterns.
In this example, we'll use the structure described by the Layered Stack Configuration Design Pattern.
In the following structure, we have many different Terraform components (Terraform root modules) in the components/terraform folder.
In the stacks/catalog folder, we define the defaults for each component using the Component Catalog Atmos
Design Pattern.
In the stacks/layers folder, we define the following layers (groups of components), and import the related components into the layer manifests:
load-balancers.yamldata.yamldns.yamllogs.yamlnotifications.yamlfirewalls.yamlnetworking.yamleks.yaml
We use the terraform.overrides section in each layer manifest to override the configurations of all the components in the layer (all Terraform
components in the layer will get the Layer and Team tags).
Finally, we import all the layer manifests into the top-level stacks.
│ # Centralized stacks configuration (stack manifests)
├── stacks
│ ├── catalog # component-specific defaults
│ │ ├── alb
│ │ │ └── defaults.yaml
│ │ ├── aurora-postgres
│ │ │ └── defaults.yaml
│ │ ├── dns
│ │ │ └── defaults.yaml
│ │ ├── eks
│ │ │ └── defaults.yaml
│ │ ├── efs
│ │ │ └── defaults.yaml
│ │ ├── msk
│ │ │ └── defaults.yaml
│ │ ├── ses
│ │ │ └── defaults.yaml
│ │ ├── sns-topic
│ │ │ └── defaults.yaml
│ │ ├── network-firewall
│ │ │ └── defaults.yaml
│ │ ├── network-firewall-logs-bucket
│ │ │ └── defaults.yaml
│ │ ├── waf
│ │ │ └── defaults.yaml
│ │ ├── vpc
│ │ │ └── defaults.yaml
│ │ └── vpc-flow-logs-bucket
│ │ └── defaults.yaml
│ ├── layers # grouping of components by category/function
│ │ ├── load-balancers.yaml
│ │ ├── data.yaml
│ │ ├── dns.yaml
│ │ ├── logs.yaml
│ │ ├── notifications.yaml
│ │ ├── firewalls.yaml
│ │ ├── networking.yaml
│ │ └── eks.yaml
│ ├── mixins
│ │ ├── tenant # tenant-specific defaults
│ │ │ └── plat.yaml
│ │ ├── region # region-specific defaults
│ │ │ ├── us-east-2.yaml
│ │ │ └── us-west-2.yaml
│ │ └── stage # stage-specific defaults
│ │ ├── dev.yaml
│ │ ├── staging.yaml
│ │ └── prod.yaml
│ └── orgs # Organizations
│ └── acme
│ ├── _defaults.yaml
│ └── plat # 'plat' represents the "Platform" OU (a.k.a tenant)
│ ├── _defaults.yaml
│ ├── dev
│ │ ├── _defaults.yaml
│ │ ├── global-region.yaml
│ │ ├── us-east-2.yaml
│ │ └── us-west-2.yaml
│ ├── staging
│ │ ├── _defaults.yaml
│ │ ├── global-region.yaml
│ │ ├── us-east-2.yaml
│ │ └── us-west-2.yaml
│ └── prod
│ ├── _defaults.yaml
│ ├── global-region.yaml
│ ├── us-east-2.yaml
│ └── us-west-2.yaml
│ # Centralized components configuration
└── components
└── terraform # Terraform components (a.k.a Terraform "root" modules)
├── alb
├── aurora-postgres
├── dns
├── eks
├── efs
├── msk
├── ses
├── sns-topic
├── network-firewall
├── network-firewall-logs-bucket
├── waf
├── vpc
└── vpc-flow-logs-bucket
Add the following minimal configuration to atmos.yaml CLI config file :
components:
terraform:
base_path: "components/terraform"
stacks:
base_path: "stacks"
name_pattern: "{tenant}-{environment}-{stage}"
included_paths:
# Tell Atmos to search for the top-level stack manifests in the `orgs` folder and its sub-folders
- "orgs/**/*"
excluded_paths:
# Tell Atmos that the `defaults` folder and all sub-folders don't contain top-level stack manifests
- "defaults/**/*"
schemas:
jsonschema:
base_path: "stacks/schemas/jsonschema"
opa:
base_path: "stacks/schemas/opa"
atmos:
manifest: "stacks/schemas/atmos/atmos-manifest/1.0/atmos-manifest.json"
Add the following configuration to the stacks/layers/load-balancers.yaml layer manifest:
import:
# Import the related component manifests into this layer manifest
- catalog/alb/defaults
# Import other Load Balancer components
# Override the configurations of all the components in this layer
# All Terraform components in this layer will get the 'Layer' and 'Team' tags
terraform:
overrides:
vars:
tags:
Layer: load-balancers
Team: Load balancer managers
Add the following configuration to the stacks/layers/data.yaml layer manifest:
import:
# Import the related component manifests into this layer manifest
- catalog/aurora-postgres/defaults
- catalog/msk/defaults
- catalog/efs/defaults
# Import other Data components
# Override the configurations of all the components in this layer
# All Terraform components in this layer will get the 'Layer' and 'Team' tags
terraform:
overrides:
vars:
tags:
Layer: data
Team: Data managers
Add the following configuration to the stacks/layers/dns.yaml layer manifest:
import:
# Import the related component manifests into this layer manifest
- catalog/dns/defaults
# Import other DNS components
# Override the configurations of all the components in this layer
# All Terraform components in this layer will get the 'Layer' and 'Team' tags
terraform:
overrides:
vars:
tags:
Layer: dns
Team: DNS managers
Add the following configuration to the stacks/layers/logs.yaml layer manifest:
import:
# Import the related component manifests into this layer manifest
- catalog/network-firewall-logs-bucket/defaults
- catalog/vpc-flow-logs-bucket/defaults
# Import other Logs components
# Override the configurations of all the components in this layer
# All Terraform components in this layer will get the 'Layer' and 'Team' tags
terraform:
overrides:
vars:
tags:
Layer: logs
Team: Log managers
Add the following configuration to the stacks/layers/notifications.yaml layer manifest:
import:
# Import the related component manifests into this layer manifest
- catalog/ses/defaults
- catalog/sns-topic/defaults
# Import other Notification components
# Override the configurations of all the components in this layer
# All Terraform components in this layer will get the 'Layer' and 'Team' tags
terraform:
overrides:
vars:
tags:
Layer: notifications
Team: Notification managers
Add the following configuration to the stacks/layers/firewalls.yaml layer manifest:
import:
# Import the related component manifests into this layer manifest
- catalog/network-firewall/defaults
- catalog/waf/defaults
# Import other Firewall components
# Override the configurations of all the components in this layer
# All Terraform components in this layer will get the 'Layer' and 'Team' tags
terraform:
overrides:
vars:
tags:
Layer: firewalls
Team: Firewall managers
Add the following configuration to the stacks/layers/networking.yaml layer manifest:
import:
# Import the related component manifests into this layer manifest
- catalog/vpc/defaults
# Import other Networking components
# Override the configurations of all the components in this layer
# All Terraform components in this layer will get the 'Layer' and 'Team' tags
terraform:
overrides:
vars:
tags:
Layer: networking
Team: Networking managers
Add the following configuration to the stacks/layers/eks.yaml layer manifest:
import:
# Import the related component manifests into this layer manifest
- catalog/eks/defaults
# Override the configurations of all the components in this layer
# All Terraform components in this layer will get the 'Layer' and 'Team' tags
terraform:
overrides:
vars:
tags:
Layer: eks
Team: EKS cluster managers
Import the required layers into the stacks/orgs/acme/plat/dev/us-east-2.yaml top-level stack manifest:
import:
# The `orgs/acme/plat/dev/_defaults` and `mixins/region/us-east-2` manifests
# define the top-level Atmos stack `plat-ue2-dev`
- orgs/acme/plat/dev/_defaults
- mixins/region/us-east-2
# Import the layers (groups of components)
- layers/load-balancers
- layers/data
- layers/dns
- layers/logs
- layers/notifications
- layers/firewalls
- layers/networking
- layers/eks
Import the required layers into the stacks/orgs/acme/plat/dev/us-west-2.yaml top-level stack manifest:
import:
# The `orgs/acme/plat/dev/_defaults` and `mixins/region/us-west-2` manifests
# define the top-level Atmos stack `plat-uw2-dev`
- orgs/acme/plat/dev/_defaults
- mixins/region/us-west-2
# Import the layers (groups of components)
- layers/load-balancers
- layers/data
- layers/dns
- layers/logs
- layers/notifications
- layers/firewalls
- layers/networking
- layers/eks
Import the required layers into the stacks/orgs/acme/plat/prod/us-east-2.yaml top-level stack manifest:
import:
# The `orgs/acme/plat/prod/_defaults` and `mixins/region/us-east-2` manifests
# define the top-level Atmos stack `plat-ue2-prod`
- orgs/acme/plat/prod/_defaults
- mixins/region/us-east-2
# Import the layers (groups of components)
- layers/load-balancers
- layers/data
- layers/dns
- layers/logs
- layers/notifications
- layers/firewalls
- layers/networking
- layers/eks
Similarly, import the required layers into the other top-level stacks for the other organizations, OUs/tenants, accounts and regions. Make sure to import only the layers that define the component that need to be provisioned in the stacks.
After the Atmos components are provisioned in the top-level stacks, all Terraform components will get the Layer and Team tags from the
corresponding layers.
Related Patterns
- Organizational Structure Configuration
- Partial Stack Configuration
- Layered Stack Configuration
- Component Catalog
- Component Catalog with Mixins