Variables

Overview

You can use this document to learn how to create and implement variables.

An environment variable is used to pass secrets to the Edge Delta agent in a secure manner. To accomplish this, the variable is added to the agent's configuration file. During runtime, the agent's local operating system environment obtains the values for the environment variables.

Review Frequently Used Environment Variables

Review Environment Variable Example for Kubernetes 

The following example is a snippet pulled from Edge Delta's GitHub repository:

spec:
  containers:
  - name: edgedelta
    image: docker.io/edgedelta/agent:latest
    env:
      - name: ED_API_KEY
        valueFrom:
          secretKeyRef:
            key: ed-api-key
            name: ed-api-key
      - name: HTTPS_PROXY
        value: <your proxy details>

Note

The ED_API_KEY variable is not defined in the configuration file as clear text.

The secret value should be defined using the Kubernetes secrets mechanism within the Kubernetes cluster.

Review the following example:

kubectl create secret generic ed-api-key --namespace=edgedelta --from-literal=ed-api-key="YOUR_API_KEY_VALUE"

Review Environment Variable Example for Kubernetes (Helm Deployment)

1. Download the values.yaml file.
2. Edit the YAML file to configure the following optional parameters:
   • Enter a secret API key instead of clear text API key
   • Edit the frequently used environment variables 
   • Define one or more custom environment variables
     • To learn more, see Review Frequently Used Environment Variables.
   • One or more custom secret environment variables, which can be used as custom environment variables but also kept as a Kubernetes secret
3. After the file is updated, follow the steps in the Install the Agent for Kubernetes with Helm document.
4. After you create a namespace, you must also create secrets, based on the instructions in the YAML file. If not, then the agent will fail to start. 

Review Environment Variable Example for Linux / MacOSX

During installation, the ED_ENV_VARS variable is used when multiple environment variables are specified in a comma-separated format, such as variable1=value1,variable2=value2.

sudo ED_API_KEY=<your api key> \
ED_ENV_VARS="HTTPS_PROXY=<your proxy details>" \
bash -c "$(curl -L https://release.edgedelta.com/release/install.sh)"

Review Environment Variable Example for Docker

docker run --rm -d --name edgedelta \
-v /var/run/docker.sock:/var/run/docker.sock:ro \
-e "ED_API_KEY=<your api key>" \
-e "HTTPS_PROXY=<your proxy details>" \
edgedelta/agent:latest

Review Environment Variable Example for Windows

On a Windows system, use the following command to define environment variables globally.

• After you set a variable, the agent service will need to be restarted.  

[System.Environment]::SetEnvironmentVariable('HTTP_PROXY', '<your proxy details>',[System.EnvironmentVariableTarget]::Machine)

Add a Variable to a Configuration File

There are 2 ways to reference variables in the configuration file:

'{{ Env "MY_VARIABLE_NAME" }}'
'{{ Env "MY_VARIABLE_NAME" "my default value" }}'

If the default value is not provided, then the variable in the agent execution environment must exist. If not, then the agent will stop with an error.

If the default value is provided, but the variable does not exist in the agent execution environment, then the default value will be used.

Note

Environment variables can only be used with string-typed inputs. In other words, if a configuration parameter expects anything besides a string, then the environment variable substitution cannot be used.

In another example, the Slack endpoint is a secret that allows posts to be directly made into a Slack channel. Instead of explicitly putting the variable into the configuration file, the variable can be referred from the agent execution environment.

Review the following example:

  triggers:
      - name: slack-integration
        type: slack
        endpoint: '{{ Env "MY_SLACK_ENDPOINT" }}'

Create a Global Configuration Variable

If your account contains multiple agents, you may want to consider setting variables that can be globally applied to several agents via the agent's configuration file. 

To better understand, review the following examples of configuration variables that you can create:

1. In the Edge Delta App, on the left-side navigation, click Data Pipeline, and then click Agent Settings.
2. Under Configuration Variables, click Add Variable. 
3. Under Name, enter a descriptive name for the global variable. 
4. Under Value, enter a configuration variable. 
5. Click Save. 
   • The newly created variable will display in the Configuration Variables table.