Support moving API key out of configuration variable

README.md

@@ -95,6 +95,8 @@ The `name` field is a unique identifier for a task. The `name` is the `task_name
 
 The `url` field is the url that will be checked for correct response JSON and/or stale data and must begin with `"http"` or `"https"`.
 
+Instead of `url`, a task may specify a `path` field, e.g. `"path": "/predictions?filter[route]=Red,Orange,Blue"`. When `path` is used, the url that is checked is built by joining the `BASE_URL` environment variable with the given `path`. If the optional `API_KEY` environment variable is also set, it will be appended to the resulting url as an `api_key` query parameter.
+
 The `active` field, if set to false, will ignore that check.
 
 The `frequency_in_seconds` is the minimum desired frequency to run a check.

lib/api_checker/application.ex

@@ -17,8 +17,18 @@ defmodule ApiChecker.Application do
     end
   end
 
+  defp load_base_url_from_env do
+    Application.put_env(:api_checker, :base_url, System.get_env("BASE_URL"))
+  end
+
+  defp load_api_key_from_env do
+    Application.put_env(:api_checker, :api_key, System.get_env("API_KEY"))
+  end
+
   def start(_type, _args) do
     load_env_vars_from_file()
+    load_base_url_from_env()
+    load_api_key_from_env()
     # List all child processes to be supervised
     children = [
       # Starts a worker by calling: ApiChecker.Worker.start_link(arg)

lib/api_checker/periodic_task.ex

@@ -34,7 +34,7 @@ defmodule ApiChecker.PeriodicTask do
          frequency_in_seconds: json["frequency_in_seconds"],
          time_ranges: time_ranges,
          name: json["name"],
-         url: json["url"],
+         url: build_url(json),
          checks: checks
        }}
     else
@@ -43,6 +43,54 @@ defmodule ApiChecker.PeriodicTask do
     end
   end
 
+  @doc """
+  Builds the url for a periodic task from its json configuration.
+
+  When `"url"` is present, it is used as-is. When `"path"` is present
+  instead, the url is built by joining the `:base_url` application
+  configuration value with the given path. In that case, if the
+  `:api_key` application configuration value is present, it is appended
+  to the url as an `api_key` query parameter.
+  """
+  def build_url(%{"url" => url}) when is_binary(url) do
+    url
+  end
+
+  def build_url(%{"path" => path}) when is_binary(path) do
+    case Application.get_env(:api_checker, :base_url) do
+      base_url when is_binary(base_url) and base_url != "" ->
+        base_url
+        |> URI.merge(path)
+        |> URI.to_string()
+        |> append_api_key(Application.get_env(:api_checker, :api_key))
+
+      _ ->
+        nil
+    end
+  end
+
+  def build_url(_) do
+    nil
+  end
+
+  defp append_api_key(url, api_key) when is_binary(api_key) and api_key != "" do
+    uri = URI.parse(url)
+
+    query =
+      (uri.query || "")
+      |> URI.decode_query(%{}, :rfc3986)
+      |> Map.put("api_key", api_key)
+      |> URI.encode_query(:rfc3986)
+
+    uri
+    |> Map.put(:query, query)
+    |> URI.to_string()
+  end
+
+  defp append_api_key(url, _api_key) do
+    url
+  end
+
   def validate(%PeriodicTask{} = task) do
     Validator.validate(task)
   end

test/api_checker/periodic_task_test.exs

@@ -1,5 +1,5 @@
 defmodule ApiChecker.PeriodicTaskTest do
-  use ExUnit.Case, async: true
+  use ExUnit.Case
   alias ApiChecker.Check.JsonCheck
   alias ApiChecker.{PeriodicTask, PeriodicTask.WeeklyTimeRange}
   doctest PeriodicTask
@@ -53,6 +53,112 @@ defmodule ApiChecker.PeriodicTaskTest do
       ignored = Map.put(@valid_periodic_task_json, "active", false)
       assert {:error, :ignored} = PeriodicTask.from_json(ignored)
     end
+
+    test "builds url from path and application base_url config when path is given" do
+      previous_base_url = Application.get_env(:api_checker, :base_url)
+
+      on_exit(fn ->
+        if previous_base_url,
+          do: Application.put_env(:api_checker, :base_url, previous_base_url),
+          else: Application.delete_env(:api_checker, :base_url)
+      end)
+
+      Application.put_env(:api_checker, :base_url, "https://api-v3.mbta.com")
+
+      json =
+        @valid_periodic_task_json
+        |> Map.drop(["url"])
+        |> Map.put("path", "/predictions?filter[route]=Red,Orange,Blue")
+
+      assert {:ok, task} = PeriodicTask.from_json(json)
+      assert task.url == "https://api-v3.mbta.com/predictions?filter[route]=Red,Orange,Blue"
+    end
+
+    test "errors when path is given but application base_url config is not set" do
+      previous_base_url = Application.get_env(:api_checker, :base_url)
+
+      on_exit(fn ->
+        if previous_base_url, do: Application.put_env(:api_checker, :base_url, previous_base_url)
+      end)
+
+      Application.delete_env(:api_checker, :base_url)
+
+      json =
+        @valid_periodic_task_json
+        |> Map.drop(["url"])
+        |> Map.put("path", "/predictions?filter[route]=Red,Orange,Blue")
+
+      assert {:error, _} = PeriodicTask.from_json(json)
+    end
+
+    test "appends api_key to url built from path when application api_key config is set" do
+      previous_base_url = Application.get_env(:api_checker, :base_url)
+      previous_api_key = Application.get_env(:api_checker, :api_key)
+
+      on_exit(fn ->
+        if previous_base_url,
+          do: Application.put_env(:api_checker, :base_url, previous_base_url),
+          else: Application.delete_env(:api_checker, :base_url)
+
+        if previous_api_key,
+          do: Application.put_env(:api_checker, :api_key, previous_api_key),
+          else: Application.delete_env(:api_checker, :api_key)
+      end)
+
+      Application.put_env(:api_checker, :base_url, "https://api-v3.mbta.com")
+      Application.put_env(:api_checker, :api_key, "secret-key")
+
+      json =
+        @valid_periodic_task_json
+        |> Map.drop(["url"])
+        |> Map.put("path", "/predictions?filter[route]=Red,Orange,Blue")
+
+      assert {:ok, task} = PeriodicTask.from_json(json)
+      uri = URI.parse(task.url)
+      assert "#{uri.scheme}://#{uri.host}#{uri.path}" == "https://api-v3.mbta.com/predictions"
+      assert URI.decode_query(uri.query) == %{"filter[route]" => "Red,Orange,Blue", "api_key" => "secret-key"}
+    end
+
+    test "appends api_key with a leading ? when the path has no query string" do
+      previous_base_url = Application.get_env(:api_checker, :base_url)
+      previous_api_key = Application.get_env(:api_checker, :api_key)
+
+      on_exit(fn ->
+        if previous_base_url,
+          do: Application.put_env(:api_checker, :base_url, previous_base_url),
+          else: Application.delete_env(:api_checker, :base_url)
+
+        if previous_api_key,
+          do: Application.put_env(:api_checker, :api_key, previous_api_key),
+          else: Application.delete_env(:api_checker, :api_key)
+      end)
+
+      Application.put_env(:api_checker, :base_url, "https://api-v3.mbta.com")
+      Application.put_env(:api_checker, :api_key, "secret-key")
+
+      json =
+        @valid_periodic_task_json
+        |> Map.drop(["url"])
+        |> Map.put("path", "/predictions")
+
+      assert {:ok, task} = PeriodicTask.from_json(json)
+      assert task.url == "https://api-v3.mbta.com/predictions?api_key=secret-key"
+    end
+
+    test "does not append api_key to an explicitly given url" do
+      previous_api_key = Application.get_env(:api_checker, :api_key)
+
+      on_exit(fn ->
+        if previous_api_key,
+          do: Application.put_env(:api_checker, :api_key, previous_api_key),
+          else: Application.delete_env(:api_checker, :api_key)
+      end)
+
+      Application.put_env(:api_checker, :api_key, "secret-key")
+
+      assert {:ok, task} = PeriodicTask.from_json(@valid_periodic_task_json)
+      assert task.url == "https://api-v3.mbta.com/predictions?filter%5Broute%5D=Red,Orange,Blue"
+    end
   end
 
   @valid_periodic_task %PeriodicTask{