Fix cached random tokens potentially not persisting on first start.

The "var/run" directory was not being created prior to the random tokens
being trying to be written. So if this directory didn't already exist
(on initial startup), this could lead to the random tokens changing on
subsequent runs.

To fix this, ensure the directory exists, but also better optimize this
process so new tokens are only generated if needed, and the file is only
written if needed (rather than rewriting it on every startup).

src/api-umbrella/cli/read_config.lua

@@ -114,41 +114,6 @@ local function read_default_config()
   nillify_yaml_nulls(config)
 end
 
--- Handle setup of random secret tokens that should be be unique for API
--- Umbrella installations, but should be persisted across restarts.
---
--- In a multi-server setup, these secret tokens will likely need to be
--- explicitly given in the server's /etc/api-umbrella/api-umbrella.yml file so
--- the secrets match across servers, but this provides defaults for a
--- single-server installation.
-local function set_cached_random_tokens()
-  -- Generate random tokens for this server.
-  local cached = {
-    web = {
-      rails_secret_token = random_token(128),
-    },
-    static_site = {
-      api_key = random_token(40),
-    },
-  }
-
-  -- See if there were any previous values for these random tokens on this
-  -- server. If so, use any of those values that might be present instead.
-  local file_path = path.join(os.getenv("API_UMBRELLA_ROOT") or "/opt/api-umbrella", "var/run/cached_random_config_values.yml")
-  local content = file.read(file_path, true)
-  if content then
-    deep_merge_overwrite_arrays(cached, lyaml.load(content))
-  end
-
-  -- Persist whatever the state of the tokens is now.
-  file.write(file_path, lyaml.dump({cached}))
-
-  -- Merge these random tokens onto the config. Note that this happens before
-  -- we read the system config (/etc/api-umbrella/api-umbrella.yml), so if
-  -- these values are defined there, these random values will be overwritten.
-  deep_merge_overwrite_arrays(config, cached)
-end
-
 -- Read the /etc/api-umbrella/api-umbrella.yml config file that provides
 -- server-specific overrides for API Umbrella configuration.
 local function read_system_config()
@@ -393,14 +358,56 @@ local function set_computed_config()
   end
 end
 
+-- Handle setup of random secret tokens that should be be unique for API
+-- Umbrella installations, but should be persisted across restarts.
+--
+-- In a multi-server setup, these secret tokens will likely need to be
+-- explicitly given in the server's /etc/api-umbrella/api-umbrella.yml file so
+-- the secrets match across servers, but this provides defaults for a
+-- single-server installation.
+local function set_cached_random_tokens()
+  -- Only generate new new tokens if they haven't been explicitly set in the
+  -- config files.
+  if not config["web"]["rails_secret_token"] or not config["static_site"]["api_key"] then
+    -- See if there were any previous values for these random tokens on this
+    -- server. If so, use any of those values that might be present instead.
+    local cached_path = path.join(config["run_dir"], "cached_random_config_values.yml")
+    local content = file.read(cached_path, true)
+    local cached = {}
+    if content then
+      cached = lyaml.load(content)
+      deep_merge_overwrite_arrays(config, cached)
+    end
+
+    -- If the tokens haven't already been written to the cache, generate them.
+    if not config["web"]["rails_secret_token"] or not config["static_site"]["api_key"] then
+      if not config["web"]["rails_secret_token"] then
+        cached["web"]["rails_secret_token"] = random_token(128)
+      end
+
+      if not config["static_site"]["api_key"] then
+        cached["static_site"] = {
+          api_key = random_token(40),
+        }
+      end
+
+      -- Persist the cached tokens.
+      dir.makepath(config["run_dir"])
+      file.write(cached_path, lyaml.dump({ cached }))
+
+      deep_merge_overwrite_arrays(config, cached)
+    end
+  end
+end
+
 -- Write out the combined and merged config to the runtime file.
 --
 -- This runtime config reflects the full state of the available config and can
 -- be used by other API Umbrella processes for reading the config (without
 -- having to actually merge and combine again).
 local function write_runtime_config()
   local runtime_config_path = path.join(config["run_dir"], "runtime_config.yml")
-  dir.makepath(path.dirname(runtime_config_path))
+  dir.makepath(config["run_dir"])
   file.write(runtime_config_path, lyaml.dump({config}))
 end
 
@@ -416,9 +423,9 @@ return function(options)
   -- writing the runtime config.
   if not config or (options and options["write"]) then
     read_default_config()
-    set_cached_random_tokens()
     read_system_config()
     set_computed_config()
+    set_cached_random_tokens()
 
     if options and options["write"] then
       write_runtime_config()