solve config yaml

README.md

@@ -1,2 +1,51 @@
-# MISeR
-A tool for interacting with Google Cloud Monitoring.
+# MISeR - A Google Cloud Monitoring Metrics Exporter
+
+MISeR is a [Prometheus Exporter](https://prometheus.io/docs/instrumenting/exporters/#exporters-and-integrations) for [Google Cloud Monitoring](https://cloud.google.com/monitoring/) metrics.
+
+It is written in Elixir and originated at [Massdriver](https://massdriver.cloud).
+
+# Features
+
+* Export metrics from Google Cloud Monitoring to Prometheus
+* Simple configuration of metrics using metric type prefixes
+* Auto discovery of resources via tags
+* Adds any available dimension labels to metrics
+
+# Configuration
+
+## Authentication
+
+The exporter is configured to use [Google Application Default Credentials](https://cloud.google.com/docs/authentication/production#automatically) to authenticate with Google Cloud Monitoring.
+
+## Configuration
+
+The exporter is configured using a YAML file. The following options are available:
+
+### Required
+
+| Option | Description |
+|--------|-------------|
+| `project_id` | The Google Cloud project ID to export metrics from. |
+| `metric_type_prefixes` | A list of metric type prefixes to export. |
+
+### Optional
+
+| Option | Description |
+|--------|-------------|
+| `user_labels` | User-defined [labels](https://cloud.google.com/resource-manager/docs/creating-managing-labels) to filter on. |
+
+### Example
+
+```yaml
+project_id: "massdriver"
+metric_type_prefixes:
+- "cloudsql.googleapis.com/database/cpu"
+user_labels:
+  environment: "prod"
+```
+
+# Scraping
+
+By default, the exporter is exposed on port `9090`, path `/metrics`.
+
+Metrics are queried at the time of scraping and are not cached.

config/prod.exs

@@ -1 +1,3 @@
 import Config
+
+config :miser, Miser.Config, file: "/config/config.yml"

config/runtime.exs

@@ -1,3 +1 @@
 import Config
-
-config :miser, Miser, YamlElixir.read_from_file!("/config/config.yml")

config/test.exs

@@ -1 +1,8 @@
 import Config
+
+config :miser, Miser.Config,
+  project_id: "my_project_id",
+  metric_type_prefixes: ["cloudsql.googleapis.com/database/cpu"],
+  user_labels: %{
+    "environment" => "dev"
+  }

docker-compose.yml

@@ -7,7 +7,11 @@ services:
     environment:
       - GOOGLE_APPLICATION_CREDENTIALS=/config/credentials.json
     volumes:
-      - ${PWD}/credentials.json:/config/credentials.json
-      - ${PWD}/config.yml:/config/config.yml
+      - type: bind
+        source: ./credentials.json
+        target: /config/credentials.json
+      - type: bind
+        source: ./config.yml
+        target: /config/config.yml
     ports:
       - "9090:9090"

lib/miser/application.ex

@@ -6,13 +6,14 @@ defmodule Miser.Application do
   @impl true
   def start(_type, _args) do
     Prometheus.Registry.register_collector(Miser.Collector)
-    Miser.setup()
 
     children = [
       {Plug.Cowboy, scheme: :http, plug: Miser.Router, port: 9090},
       {Goth, name: Miser.Goth}
     ]
 
+    :ok = Miser.Config.configure()
+
     opts = [strategy: :one_for_one, name: Miser.Supervisor]
     Supervisor.start_link(children, opts)
   end

lib/miser/collector.ex

@@ -12,19 +12,17 @@ defmodule Miser.Collector do
   """
   use Prometheus.Collector
 
-  alias Miser.Client
+  alias Miser.{Client, Config}
   alias Miser.Client.{ListMetricDescriptorsRequest, ListTimeSeriesRequest}
   alias Prometheus.Model
 
   @impl true
   @spec collect_mf(any, any) :: :ok
   def collect_mf(_registry, callback) do
-    config = Application.get_env(:miser, Miser)
-    project_id = Map.fetch!(config, "project_id")
-    user_labels = Map.get(config, "user_labels", %{})
+    project_id = Config.project_id()
+    user_labels = Config.user_labels()
 
-    config
-    |> Map.get("metric_type_prefixes", [])
+    Config.metric_type_prefixes()
     # should probably parallelize this
     |> Enum.each(fn metric_type_prefix ->
       request = %ListMetricDescriptorsRequest{

lib/miser/config.ex

@@ -0,0 +1,43 @@
+defmodule Miser.Config do
+  @moduledoc """
+  Managed Miser config.any()
+
+  This useful wrapper lets us evaluate config files for when this thing is configured on k8s.
+  """
+
+  def configure do
+    Application.get_env(:miser, __MODULE__)
+    |> Keyword.get(:file)
+    |> case do
+      nil -> :ok
+      file -> evaluate_config_file(file)
+    end
+  end
+
+  def project_id do
+    Application.fetch_env!(:miser, __MODULE__)
+    |> Keyword.fetch!(:project_id)
+  end
+
+  def user_labels do
+    Application.fetch_env!(:miser, __MODULE__)
+    |> Keyword.get(:user_labels, [])
+  end
+
+  def metric_type_prefixes do
+    Application.fetch_env!(:miser, __MODULE__)
+    |> Keyword.fetch!(:metric_type_prefixes)
+  end
+
+  def evaluate_config_file(path) do
+    config_map = YamlElixir.read_from_file!(path)
+
+    config = [
+      project_id: Map.fetch!(config_map, "project_id"),
+      user_labels: Map.get(config_map, "user_labels", %{}),
+      metric_type_prefixes: Map.fetch!(config_map, "metric_type_prefixes")
+    ]
+
+    Application.put_env(:miser, __MODULE__, config)
+  end
+end