Add support for YAML configuration files

README.md

@@ -33,8 +33,9 @@ normally support App Connectors.
 
 ## Example
 
-Here is a sample config file, in JSON format:
+Create a configuration file in either JSON or YAML format. Here’s an example:
 
+`config.json`
 ```json
 {
   "routes": [
@@ -44,12 +45,25 @@ Here is a sample config file, in JSON format:
   "hostRoutes": [
     "github.com",
     "private-app.example.com"
-  ],
+  ],̌
   "awsManagedPrefixLists": [
     "pl-02761f4a40454a3c9"
   ]
 }
 ```
+or `config.yaml`
+```yaml
+routes:
+  - "172.16.0.0/22"
+  - "192.168.0.0/24"
+hostRoutes:
+  - "special-hostname1.example"
+  - "special-hostname2.example"
+awsManagedPrefixLists:
+  - "pl-02761f4a40454a3c9"
+extraArgs:
+  - "--webclient"
+```
 
 Run tailscale-manager:
 

src/TailscaleManager.hs

@@ -1,4 +1,4 @@
--- | Tailscale Routes Manager
+{-# LANGUAGE QuasiQuotes #-}
 
 module TailscaleManager where
 
@@ -14,7 +14,6 @@ import Prettyprinter (Doc)
 import System.Log.Logger
 import System.Process (callProcess, showCommandForUser)
 import Text.RawString.QQ (r)
-
 import TailscaleManager.Config
 import TailscaleManager.Discovery.AWSManagedPrefixList (resolveAllPrefixLists)
 import TailscaleManager.Discovery.DNS (resolveHostnamesToRoutes)
@@ -40,7 +39,7 @@ helpText = [r|Tailscale routes manager
 Dynamically resolves a list of hostRoutes to IP addresses, then tells tailscale
 to advertise them as /32 routes along with any normal CIDR routes.
 
-Config file example:
+Config file example (JSON):
 
 {
   "routes": [
@@ -49,7 +48,7 @@ Config file example:
   ],
   "hostRoutes": [
     "special-hostname1.example",
-    "special-hostname2.example",
+    "special-hostname2.example"
   ],
   "awsManagedPrefixLists": [
     "pl-02761f4a40454a3c9"
@@ -60,7 +59,7 @@ Config file example:
 tsManagerOptions :: Parser TailscaleManagerOptions
 tsManagerOptions =
   TailscaleManagerOptions
-  <$> argument str (metavar "<configfile.json>")
+  <$> argument str (metavar "<configfile>")
   <*> switch (long "dryrun"
               <> help "Dryrun mode")
   <*> strOption (long "tailscale"
@@ -120,7 +119,7 @@ runOnce options prevRoutes = do
           logL logger DEBUG ("Sleeping for " ++ show (interval options) ++ " seconds")
         threadDelay (interval options * 1000000)  -- microseconds
 
-  config <- loadConfig (configFile options)
+  config <- TailscaleManager.Config.loadConfig (configFile options)
   newRoutes <- generateRoutes config
 
   logDiff prevRoutes newRoutes
@@ -137,7 +136,7 @@ runOnce options prevRoutes = do
       logDelay
       return prevRoutes
 
--- |Emit a log message describing the difference between old and new route sets.
+-- | Emit a log message describing the difference between old and new route sets.
 logDiff :: Set IPRange -> Set IPRange -> IO ()
 logDiff prevRoutes newRoutes = do
   logger <- myLogger
@@ -154,18 +153,11 @@ logDiff prevRoutes newRoutes = do
     routesToRemove  = S.difference prevRoutes newRoutes
     routesUnchanged = S.intersection prevRoutes newRoutes
 
--- |Compute how much the smaller the new set is vs old.
---
--- >>> shrinkRatio ["1.1.1.1/32", "2.2.2.2/32"] ["1.1.1.1/32"]
--- 0.5
-shrinkRatio :: Foldable t
-            => t a  -- ^ Old set
-            -> t a  -- ^ New set
-            -> Double    -- ^ Shrink ratio
+-- | Compute how much smaller the new set is vs old.
+shrinkRatio :: Foldable t => t a -> t a -> Double
 shrinkRatio old new = 1 - (1 / (fromIntegral (length old) / fromIntegral (length new)))
 
--- |Do all the hostname resolution and concat the results with static routes from
--- the config.
+-- | Generate routes based on config, resolving hostnames and AWS-managed prefix lists.
 generateRoutes :: TSConfig -> IO (Set IPRange)
 generateRoutes config = do
   hostRoutes <- resolveHostnamesToRoutes (tsHostRoutes config)

src/TailscaleManager/Config.hs

@@ -3,15 +3,14 @@
 module TailscaleManager.Config where
 
 import Data.Aeson
+import Data.Aeson (eitherDecodeFileStrict)
 import Data.Aeson.IP ()
 import Data.ByteString.Lazy qualified as LB
 import Data.IP (IPRange)
 import Data.Maybe (fromMaybe)
 import Data.Text
-
--- |Parse our config file.  May throw AesonException on failure.
-loadConfig :: FilePath -> IO TSConfig
-loadConfig fp = LB.readFile fp >>= throwDecode
+import System.FilePath (takeExtension)
+import Data.Yaml (decodeFileEither)
 
 -- |Config file schema
 data TSConfig
@@ -35,3 +34,27 @@ instance FromJSON TSConfig where
                      , tsExtraArgs = fromMaybe [] extraArgs
                      , tsAWSManagedPrefixLists = fromMaybe [] awsManagedPrefixLists
                      })
+
+-- | Load configuration from a file, detecting format based on file extension.
+loadConfig :: FilePath -> IO TSConfig
+loadConfig path = do
+  case takeExtension path of
+    ".json" -> loadConfigFromJSON path
+    ".yaml" -> loadConfigFromYAML path
+    _       -> error "Unsupported file format. Please use .json or .yaml."
+
+-- | Load configuration from a JSON file.
+loadConfigFromJSON :: FilePath -> IO TSConfig
+loadConfigFromJSON path = do
+  result <- eitherDecodeFileStrict path
+  case result of
+    Left err -> error $ "Failed to parse JSON config: " ++ err
+    Right config -> return config
+
+-- | Load configuration from a YAML file.
+loadConfigFromYAML :: FilePath -> IO TSConfig
+loadConfigFromYAML path = do
+  result <- decodeFileEither path
+  case result of
+    Left err -> error $ "Failed to parse YAML config: " ++ show err
+    Right config -> return config

tailscale-manager.cabal

@@ -50,6 +50,8 @@ common deps
       , protolude ^>= 0.3.4
       , raw-strings-qq ^>= 1.1
       , text ^>= 2.0.2
+      , filepath ^>= 1.4.2
+      , yaml ^>= 0.11.8
 
 executable tailscale-manager
     import:           warnings, deps