From 76faebd234644d77429ddcefaf8ccdb8a1beff0d Mon Sep 17 00:00:00 2001 From: Ben Busby Date: Fri, 22 Oct 2021 20:07:07 -0600 Subject: [PATCH] Move constants to config, update string formatting Not sure if this is the Elixir-y way to do this, but seems more logical than hardcoding values such as redis connection. Also went through and improved how string formatting was performed throughout the app. Rather than "combining" <> "strings" this way, I'm now just doing "#${variable}#{formatting}", which looks a lot cleaner. --- config/config.exs | 7 ++++++ lib/privacy_revolver/application.ex | 3 ++- lib/privacy_revolver/router.ex | 27 ++++++++++++++++++---- update.exs | 36 ++++++++++++++++------------- 4 files changed, 51 insertions(+), 22 deletions(-) create mode 100644 config/config.exs diff --git a/config/config.exs b/config/config.exs new file mode 100644 index 0000000..44b3af8 --- /dev/null +++ b/config/config.exs @@ -0,0 +1,7 @@ +import Config + +config :privacy_revolver, + redis_conn: "redis://localhost:6379", + fallback_str: "-fallback", + update_file: ".update-results", + services_json: "services.json" diff --git a/lib/privacy_revolver/application.ex b/lib/privacy_revolver/application.ex index e303646..04b7540 100644 --- a/lib/privacy_revolver/application.ex +++ b/lib/privacy_revolver/application.ex @@ -1,4 +1,5 @@ defmodule PrivacyRevolver.Application do + @redis_conn Application.fetch_env!(:privacy_revolver, :redis_conn) @moduledoc false use Application @@ -7,7 +8,7 @@ defmodule PrivacyRevolver.Application do def start(_type, _args) do children = [ Plug.Cowboy.child_spec(scheme: :http, plug: PrivacyRevolver.Router, options: [port: 4001]), - {Redix, {"redis://localhost:6379", [name: :redix]}} + {Redix, {@redis_conn, [name: :redix]}} ] opts = [strategy: :one_for_one, name: PrivacyRevolver.Supervisor] diff --git a/lib/privacy_revolver/router.ex b/lib/privacy_revolver/router.ex index c2c1c61..7d4e82f 100644 --- a/lib/privacy_revolver/router.ex +++ b/lib/privacy_revolver/router.ex @@ -1,9 +1,15 @@ defmodule PrivacyRevolver.Router do + @fallback_str Application.fetch_env!(:privacy_revolver, :fallback_str) + use Plug.Router plug :match plug :dispatch + get "/" do + send_resp(conn, 200, "") + end + get "/ping" do # Useful for app healthcheck {:ok, resp} = Redix.command(:redix, ["PING"]) @@ -11,19 +17,30 @@ defmodule PrivacyRevolver.Router do end get "/:service/*glob" do - full_path = "/" <> Enum.join(glob, "/") - {:ok, instances} = Redix.command(:redix, ["LRANGE", service, "0", "-1"]) + path = Enum.join(glob, "/") + {:ok, instances} = Redix.command( + :redix, + ["LRANGE", service, "0", "-1"] + ) - # Either pick a random available instance, or fall back to the default one + # Either pick a random available instance, + # or fall back to the default one instance = if Enum.count(instances) > 0 do Enum.random(instances) else - Redix.command(:redix, ["GET", service <> "-fallback"]) + {:ok, result} = Redix.command( + :redix, + ["GET", "#{service}#{@fallback_str}"] + ) + result end # Redirect to the available instance conn |> Plug.Conn.resp(:found, "") |> - Plug.Conn.put_resp_header("location", instance <> full_path) + Plug.Conn.put_resp_header( + "location", + "#{instance}/#{path}" + ) end end diff --git a/update.exs b/update.exs index 65110f6..9ed320d 100644 --- a/update.exs +++ b/update.exs @@ -8,6 +8,15 @@ defmodule Service do end defmodule Instances do + @fallback_str Application.fetch_env!(:privacy_revolver, :fallback_str) + @update_file Application.fetch_env!(:privacy_revolver, :update_file) + @services_json Application.fetch_env!(:privacy_revolver, :services_json) + + def init() do + File.rename(@update_file, "#{@update_file}-prev") + update(@services_json) + end + def request(url) do case HTTPoison.get(url) do {:ok, %HTTPoison.Response{status_code: 200}} -> @@ -19,10 +28,6 @@ defmodule Instances do end def update(filename) do - {:ok, conn} = Redix.start_link( - "redis://localhost:6379", - name: :redix - ) {:ok, file} = File.read(filename) {:ok, json} = Poison.decode(file, as: [%Service{}]) @@ -32,20 +37,20 @@ defmodule Instances do request(instance_url <> service.test_url) == :good end) - add_to_redis(conn, service, result) + add_to_redis(service, result) log_results(service.type, result) end end - def add_to_redis(conn, service, instances) do + def add_to_redis(service, instances) do # Remove previous list of instances - Redix.command(conn, [ + Redix.command(:redix, [ "DEL", service.type ]) # Update with new list of available instances - Redix.command(conn, [ + Redix.command(:redix, [ "LPUSH", service.type ] ++ instances) @@ -53,26 +58,25 @@ defmodule Instances do # Set fallback to one of the available instances, # or the default instance if all are "down" if Enum.count(instances) > 0 do - Redix.command(conn, [ + Redix.command(:redix, [ "SET", - service.type <> "-fallback", + "#{service.type}#{@fallback_str}", Enum.random(instances) ]) else - Redix.command(conn, [ + Redix.command(:redix, [ "SET", - service.type <> "-fallback", + "#{service.type}#{@fallback_str}", service.fallback ]) end end def log_results(service_name, results) do - {:ok, file} = File.open(".update-results", [:append, {:delayed_write, 100, 20}]) - IO.write(file, service_name <> ": " <> inspect(results) <> "\n") + {:ok, file} = File.open(@update_file, [:append, {:delayed_write, 100, 20}]) + IO.write(file, "#{service_name}: #{inspect(results)}\n") File.close(file) end end -File.rename(".update-results", ".update-results-prev") -Instances.update("services.json") +Instances.init()