diff --git a/tools/lambda-promtail/main.tf b/tools/lambda-promtail/main.tf index 11c97513798d..a7ef7b76b687 100644 --- a/tools/lambda-promtail/main.tf +++ b/tools/lambda-promtail/main.tf @@ -245,9 +245,26 @@ resource "aws_lambda_permission" "lambda_promtail_allow_cloudwatch" { principal = "logs.${data.aws_region.current.name}.amazonaws.com" } -# This block allows for easily subscribing to multiple log groups via the `log_group_names` var. -# However, if you need to provide an actual filter_pattern for a specific log group you should -# copy this block and modify it accordingly. +# Providing a log group prefix of "" enables matching _all_ log groups +data "aws_cloudwatch_log_groups" "lambdafunction_logs" { + for_each = var.log_group_prefixes + + log_group_name_prefix = each.value +} + +locals { + # Combine prefix-generated names from the data source call with the explicitly defined + # names to get the full set of log groups to create subscription filters for. + # Be sure to remove "/aws/lambda/${var.name}" so we don't log ourselves into oblivion. + log_group_names = setsubtract( + setunion( + var.log_group_names, + data.aws_cloudwatch_log_groups.lambdafunction_logs.log_group_names + ), + toset(["/aws/lambda/${var.name}"]) + ) +} + resource "aws_cloudwatch_log_subscription_filter" "lambdafunction_logfilter" { for_each = var.log_group_names @@ -255,8 +272,9 @@ resource "aws_cloudwatch_log_subscription_filter" "lambdafunction_logfilter" { log_group_name = each.value destination_arn = aws_lambda_function.this.arn - # required but can be empty string - filter_pattern = "" + # Default to no filter at all (empty string), but allow callers to narrow their + # search as desired. + filter_pattern = lookup(var.log_group_subscription_filter_patterns, each.value, "") } #------------------------------------------------------------------------------- diff --git a/tools/lambda-promtail/variables.tf b/tools/lambda-promtail/variables.tf index 74dceb1a4a19..103db5645e46 100644 --- a/tools/lambda-promtail/variables.tf +++ b/tools/lambda-promtail/variables.tf @@ -28,6 +28,18 @@ variable "log_group_names" { default = [] } +variable "log_group_prefixes" { + type = set(string) + description = "List of prefixes to match CloudWatch Log Group names to create Subscription Filters for." + default = [] +} + +variable "log_group_subscription_filter_patterns" { + type = map(string) + description = "Filter subscription patterns. The key is the log group and the value is the filter pattern." + default = {} +} + variable "lambda_promtail_image" { type = string description = "The ECR image URI to pull and use for lambda-promtail."