Scoped Variables
Last updated
Last updated
In any piece of software or code, variables are used for holding data such as numbers or strings. Variables are created by declaring them, which involves specifying the variable's name and type, followed by assigning it a value.
Devtron offers super-admins the capability to define scoped variables (key-value pairs). It means, while the key remains the same, its value may change depending on the following context:
Global: Variable value will be universally same throughout Devtron.
Advantages of using scoped variables
Reduces repeatability: Configuration management team can centrally maintain the static data.
Simplifies bulk edits: All the places that use a variable get updated when you change the value of the variable.
Keeps data secure: You can decide the exposure of a variable's value to prevent misuse or leakage of sensitive data.
On Devtron, a super-admin can download a YAML template. It will contain a schema for defining the variables.
From the left sidebar, go to Global Configurations → Scoped Variables
Click Download template.
Open the downloaded template using any code editor (say VS Code).
The YAML file contains key-value pairs that follow the below schema:
The spec.values
array further contains the following elements:
Here's a truncated template containing the specification of two variables for your understanding:
Once you save the YAML file, go back to the screen where you downloaded the template.
Use the file uploader utility to upload your YAML file.
The content of the file will be uploaded for you to review and edit. Click Review Changes.
You may check the changes between the last saved file and the current one before clicking Save.
Click the Variable List tab to view the variables. Check the How to Use a Scoped Variable section to know more.
Only a super-admin can edit existing scoped variables.
Option 1: Directly edit using the UI
Option 2: Reupload the updated YAML file
Reuploading the YAML file will replace the previous file, so any variable that existed in the previous file but not in the latest one will be lost
Once a variable is defined, it can be used by your authorized users on Devtron. A scoped variable widget would appear only on the screens that support its usage.
Currently, the widget is shown only on the following screens in App Configuration:
Workflow Editor → Edit build pipeline → Pre-build stage (tab)
Workflow Editor → Edit build pipeline → Post-build stage (tab)
Workflow Editor → Edit deployment pipeline → Post-Deployment stage (tab)
Workflow Editor → Edit deployment pipeline → Post-Deployment stage (tab)
Deployment Template
ConfigMaps
Secrets
Upon clicking on the widget, a list of variables will be visible.
Use the copy button to copy a relevant variable of your choice.
It would appear in the following format upon pasting it within an input field: @{{variable-name}}
When multiple values are associated with a scoped variable, the precedence order is as follows, with the highest priority at the top:
Global
Environment + App: This is the most specific scope, and it will take precedence over all other scopes. For example, the value of DB name
variable for the app1
application in the prod
environment would be app1-p
, even though there is a global DB name
variable set to Devtron
. If a variable value for this scope is not defined, the App scope will be checked.
App: This is the next most specific scope, and it will take precedence over the Environment
, Cluster
, and Global
scopes. For example, the value of DB name
variable for the app1
application would be project-tahiti
, even though the value of DB name
exists in lower scopes. If a variable value for this scope is not defined, the Environment scope will be checked.
Environment: This is the next most specific scope, and it will take precedence over the Cluster
and Global
scopes. For example, the value of DB name
variable in the prod
environment would be devtron-prod
, even though the value of DB name
exists in lower scopes. If a variable value for this scope is not defined, the Cluster scope will be checked.
Cluster: This is the next most specific scope, and it will take precedence over the Global
scope. For example, the value of DB name
variable in the gcp-gke
cluster would be Devtron-gcp
, even though there is a global DB name
variable set to Devtron-gcp
. If a variable value for this scope is not defined, the Global scope will be checked.
Global: This is the least specific scope, and it will only be used if no variable values are found in other higher scopes. The value of DB name
variable would be Devtron
.
There are some system variables that exist by default in Devtron that you can readily use if needed:
DEVTRON_NAMESPACE: Provides name of the namespace
DEVTRON_CLUSTER_NAME: Provides name of the cluster configured on Devtron
DEVTRON_ENV_NAME: Provides name of the environment
DEVTRON_IMAGE_TAG: Provides image tag associated with the container image
DEVTRON_IMAGE: Provides full image path of the container image, e.g., gcr.io/k8s-minikube/kicbase:v0.0.39
DEVTRON_APP_NAME: Provides name of the application on Devtron
Currently, these variables do not appear in the scoped variable widget, but you may use them.
Field | Type | Description |
---|---|---|
Field | Type | Description |
---|---|---|
apiVersion
string
The API version of the resource (comes pre-filled)
kind
string
The kind of resource (i.e. Variable, comes pre-filled)
spec
object
The complete specification object containing all the variables
spec.name
string
Unique name of the variable, e.g. DB_URL
spec.shortDescription
string
A short description of the variable (up to 120 characters)
spec.notes
string
Additional details about the variable (will not be shown on UI)
spec.isSensitive
boolean
Whether the variable value is confidential (will not be shown on UI if true)
spec.values
array
The complete values object containing all the variable values as per context
category
string
The context, e.g., Global, Cluster, Application, Env, ApplicationEnv
value
string
The value of the variable
selectors
object
A set of selectors that restrict the scope of the variable
selectors.attributeSelectors
object
A map of attribute selectors to values
selectors.attributeSelectors.<selector_key>
string
The key of the attribute selector, e.g., ApplicationName, EnvName, ClusterName
selectors.attributeSelectors.<selector_value>
string
The value of the attribute selector