Terraform: Property file to env section - terraform

Question

I have a .properties and I'd like to apply a template to generate env {} entries to my deployment.
Something like this:
{{- range $key, $value := .Values.configurationOverrides }}
env {
name = {{ printf "REST_%s" $key | replace "." "_" | upper | quote }}
value =
Generate env {} entries:
...
spec {
container {
image = "**"
name = "rest"
env {
name = "REST_FROM_PROPERTIES_FILE"
value = "VALUE FROM PROPERTIES FILE"
}
...
Is it possible?
Thanks.

Answer 1

Note: I assume you use Terraform 0.12.x
One part of the solution is dynamic blocks which allow you to loop over a list of values and dynamically add env sections:
properties_list = [{ name: "MY_ENV_VAR", value: "VALUE", },]
dynamic "env" {
for_each = var.properties_list
name = env.value.name
value = env.value.value
}
The hard part is parsing the properties file, as there is no out of the box way to do it in Terraform. You can use something like jsondecode to decode JSON into a terraform object. So you could first transform your properties file into a JSON file (For example, using this npm package) and then decode that into a terraform object.

Answer 2

Following the help of Blokje5 I managed to make it with variables. It's not really loading from properties file, but it fitted my needs (which was not change Terraform code when need to change config/env vars) :
File terraform.tfvars:
kafka-rest-envs = {
KAFKA_REST_BOOTSTRAP_SERVERS = "localhost:9092"
KAFKA_REST_HOST_NAME = "hostnamey"
KAFKA_REST_ID = "kafka-rest"
KAFKA_REST_LISTENERS = "http://0.0.0.0:8082"
KAFKA_REST_CLIENT_SASL_JAAS_CONFIG = "***"
KAFKA_REST_CLIENT_SECURITY_PROTOCOL = "SASL_SSL"
KAFKA_REST_CLIENT_SSL_ENDPOINT_IDENTIFICATION_ALGORITHM = "https"
KAFKA_REST_CONSUMER_RETRY_BACKOFF_MS = "500"
KAFKA_REST_CONSUMER_REQUEST_TIMEOUT_MS = "25000"
KAFKA_REST_PRODUCER_ACKS = "1"
KAFKA_REST_CLIENT_SASL_MECHANISM = "PLAIN"
KAFKA_REST_ADMIN_REQUEST_TIMEOUT_MS = "50000"
KAFKA_REST_KEY_SERIALIZER = "io.confluent.kafka.serializers.KafkaAvroSerializer"
KAFKA_REST_VALUE_SERIALIZER = "io.confluent.kafka.serializers.KafkaAvroSerializer"
}
And the Terraform:
...
spec {
container {
image = "confluentinc/cp-kafka-rest"
name = "kafka-rest"
dynamic "env" {
for_each = var.kafka-rest-envs
content {
name = env.key
value = env.value
}
}
...
Thank you!