Use environment variables in Telegraf configurations

Use environment variables anywhere in the configuration file by enclosing them in ${}. Telegraf replaces variables before parsing the file, so a variable can supply any part of the configuration.

Quoting follows the TOML type of the value:

• For strings, put the variable inside quotes, such as "${STR_VAR}".
• For numbers and booleans, leave the variable unquoted, such as ${INT_VAR} or ${BOOL_VAR}.
• In double-quoted strings, escape backslashes, such as "C:\\Program Files". For values that contain a single backslash, use a single-quoted literal string, such as 'C:\Program Files'. See Basic strings and literal strings.

Expansion forms

Telegraf supports shell parameter expansion for environment variables:

• ${VARIABLE}: the value of VARIABLE.
• ${VARIABLE:-default}: default if VARIABLE is unset or empty.
• ${VARIABLE-default}: default only if VARIABLE is unset.
• ${VARIABLE:?err}: exits with an error message containing err if VARIABLE is unset or empty.
• ${VARIABLE?err}: exits with an error message containing err if VARIABLE is unset.

Where to define variables

Define variables in the environment that starts Telegraf, such as your shell, a systemd unit, or a container environment. When using the .deb or .rpm packages, define environment variables in /etc/default/telegraf. The service reads this file at startup.

Example

Define the variables:

# /etc/default/telegraf
INFLUX_HOST="http://localhost:8181"
INFLUX_TOKEN="replace_with_your_token"
INFLUX_DATABASE="telegraf"

Reference them in the configuration file:

[global_tags]
  user = "${USER}"

[[inputs.mem]]

[[outputs.influxdb_v3]]
  urls = ["${INFLUX_HOST}"]
  token = "${INFLUX_TOKEN}"
  database = "${INFLUX_DATABASE}"

After substitution, Telegraf parses the effective configuration:

[global_tags]
  user = "alice"

[[inputs.mem]]

[[outputs.influxdb_v3]]
  urls = ["http://localhost:8181"]
  token = "replace_with_your_token"
  database = "telegraf"