Use dynamic values in configurations

Use dynamic values in your Telegraf configurations and reuse a single configuration for multiple distinct agents or across environments.

Telegraf Controller supports the following dynamic value types:

• Parameters for values you want to set or override per agent.
• Environment variables for values provided by the running Telegraf agent.
• Secrets for sensitive values stored in an external secret store.

Parameters

Use parameters for values that change between agents, deployments, or environments. Define the parameter where the configuration is easy to find, and then reference it in plugin settings. Configuration parameters are a feature of Telegraf Controller and are not part of the Telegraf project.

Use the following syntax:

&{param_name[:default_value]}

Parameters do not require a default value. Any parameter without a default value is considered required and must be defined when requesting the configuration from Telegraf Controller.

Use parameters in Telegraf configurations

[[outputs.influxdb_v2]]
  # Parameter with a default value
  urls = ["&{db_host:https://localhost:8181}"]

[[outputs.heartbeat]]
  # Required parameter without a default value
  instance_id = "&{agent_id}"

The example above uses two parameters:

• db_host with a default value of https://localhost:8181
• agent_id (Required)

Define parameters

Use URL-encoded query parameters to define parameter values when requesting a configuration’s TOML. The Telegraf Controller API returns the TOML with replaced parameters.

For readability, the following example uses Shell variables to build the configuration URL with query parameters for each configuration parameter:

configUrl="http://localhost:8888/api/configs/xxxxxx/toml"
params="?db_host=https%3A%2F%2Fmydomain%3A8181"
params+="&agent_id=agent123"
configUrl+=$params

telegraf \
  --config $configUrl

If requesting the example configuration above, Telegraf would load the following TOML configuration:

[[outputs.influxdb_v2]]
  # Parameter with a default value
  urls = ["https://mydomain:8181"]

[[outputs.heartbeat]]
  # Required parameter without a default value
  instance_id = "agent123"

Environment Variables

Use environment variables for values that Telegraf reads from the agent environment at runtime. Provide a default to keep the configuration portable across environments.

Use the following syntax:

${VAR_NAME[:-default_value]}

Environment variables do not require a default value. Any environment variable without a default value is considered required and must be defined in the Telegraf agent’s environment when using the configuration.

For more information about Telegraf environment variable syntax, see Telegraf configuration options—Set environment variables.

Use environment variables in Telegraf configurations

[[inputs.http]]
  urls = ["${API_ENDPOINT:-http://localhost:8080}/metrics"]

  [inputs.http.headers]
    Authorization = "Bearer ${AUTH_TOKEN}"

The example above uses two environment variables:

• API_ENDPOINT with a default value of http://localhost:8080
• AUTH_TOKEN (Required)

Define environment variables at runtime

Telegraf loads environment variables from the agent runtime environment.

API_ENDPOINT=https://mydomain.com/metrics
AUTH_TOKEN=x00x0xx00xxxX0xXXx0000xxxX000x00XXxXx

telegraf \
  --config "http://localhost:8888/api/configs/xxxxxx/toml"

Secrets

Use secrets for credentials or tokens you do not want to store in plain text. Secrets require a secret store and its corresponding secretstores plugin.

# Configure a secret store plugin
[[secretstores.vault]]
  id = "my_vault"
  address = "my_vault:8200"
  token_file = "/path/to/auth/token"
  # ...

# Use secrets from the configured secret store
[[outputs.influxdb_v2]]
  host = "my_influxdb.com:8181"
  token = "@{my_vault:influx_token}"

For more information about Telegraf secrets and secret stores, see Telegraf configuration options—Secret stores.

When using secrets:

• Configure the secret store plugin in the same configuration.
• Use a stable id so references to a secret store remain consistent.
• Ensure the Telegraf agent can reach and authenticate with the secret store.