feat: Read config directly from environment variables

resolves PostgREST#1624

main/Main.hs

@@ -33,8 +33,9 @@ import Text.Printf              (hPrintf)
 
 import PostgREST.App         (postgrest)
 import PostgREST.Config      (AppConfig (..), CLI (..), Command (..),
-                              configDbPoolTimeout', dumpAppConfig,
-                              prettyVersion, readCLIShowHelp,
+                              Environment, configDbPoolTimeout',
+                              dumpAppConfig, prettyVersion,
+                              readCLIShowHelp, readEnvironment,
                               readValidateConfig)
 import PostgREST.DbStructure (getDbStructure, getPgVersion)
 import PostgREST.Error       (PgError (PgError), checkIsFatal,
@@ -63,11 +64,14 @@ main = do
   hSetBuffering stdin LineBuffering
   hSetBuffering stderr NoBuffering
 
+  -- read PGRST_ env variables
+  env <- readEnvironment
+
   -- read path from commad line
-  opts <- readCLIShowHelp
+  opts <- readCLIShowHelp env
 
   -- build the 'AppConfig' from the config file path
-  conf <- readValidateConfig $ cliPath opts
+  conf <- readValidateConfig env $ cliPath opts
 
   -- These are config values that can't be reloaded at runtime. Reloading some of them would imply restarting the web server.
   let
@@ -140,10 +144,11 @@ main = do
     Catch connWorker
     ) Nothing
 
-  -- Re-read the config on SIGUSR2
-  void $ installHandler sigUSR2 (
-    Catch $ reReadConfig (cliPath opts) refConf
-    ) Nothing
+  -- Re-read the config on SIGUSR2, but only if we have a config file
+  when (isJust $ cliPath opts) $
+    void $ installHandler sigUSR2 (
+      Catch $ reReadConfig env (cliPath opts) refConf
+      ) Nothing
 #endif
 
   -- reload schema cache on NOTIFY
@@ -330,12 +335,12 @@ listener dbUri dbChannel pool refConf refDbStructure mvarConnectionStatus connWo
     errorMessage = "Could not listen for notifications on the " <> dbChannel <> " channel" :: Text
     retryMessage = "Retrying listening for notifications on the " <> dbChannel <> " channel.." :: Text
 
+#ifndef mingw32_HOST_OS
 -- | Re-reads the config at runtime. Invoked on SIGUSR2.
 -- | If it panics(config path was changed, invalid setting), it'll show an error but won't kill the main thread.
-#ifndef mingw32_HOST_OS
-reReadConfig :: FilePath -> IORef AppConfig -> IO ()
-reReadConfig path refConf = do
-  conf <- readValidateConfig path
+reReadConfig :: Environment -> Maybe FilePath -> IORef AppConfig -> IO ()
+reReadConfig env path refConf = do
+  conf <- readValidateConfig env path
   atomicWriteIORef refConf conf
   putStrLn ("Config file reloaded" :: Text)
 #endif

nix/docker/README.md

@@ -2,8 +2,8 @@
 
 In order to build an optimal PostgREST Docker image, we create the image from
 scratch (i.e., without a parent image like `debian` or `alpine`), and only
-include the files that are essential for running PostgREST (the static
-PostgREST binary and a `postgrest.conf`).
+include the file that is essential for running PostgREST: the static
+PostgREST binary.
 
 This is similar to what you would get with the following `Dockerfile`:
 
@@ -17,12 +17,6 @@ FROM scratch
 # need to include for running the application.
 ADD /absolute/path/to/postgrest /bin/postgrest
 
-# Include a default configuration file.
-ADD /absolute/path/to/postgrest.conf /etc/postgrest.conf
-
-ENV PGRST_DB_URI= \
-    ...
-
 EXPOSE 3000
 
 # This is the user id that Docker will run our image under by default. Note
@@ -32,7 +26,7 @@ EXPOSE 3000
 # can be run under any user you specify.
 USER 1000
 
-CMD [ "/bin/postgrest", "/etc/postgrest.conf" ]
+CMD [ "/bin/postgrest" ]
 ```
 
 # Building the Docker image with Nix

nix/docker/default.nix

@@ -4,9 +4,6 @@
 , checkedShellScript
 }:
 let
-  config =
-    ./postgrest.conf;
-
   image =
     dockerTools.buildImage {
       name = "postgrest";
@@ -19,34 +16,11 @@ let
 
       extraCommands =
         ''
-          mkdir etc
-          cp ${config} etc/postgrest.conf
           rmdir share
         '';
 
       config = {
-        Cmd = [ "/bin/postgrest" "/etc/postgrest.conf" ];
-        Env = [
-          "PGRST_DB_URI=postgresql://?user=postgres"
-          "PGRST_DB_SCHEMA=public"
-          "PGRST_DB_ANON_ROLE="
-          "PGRST_DB_POOL=100"
-          "PGRST_DB_POOL_TIMEOUT=10"
-          "PGRST_DB_EXTRA_SEARCH_PATH=public"
-          "PGRST_DB_CHANNEL=pgrst"
-          "PGRST_DB_CHANNEL_ENABLED=false"
-          "PGRST_SERVER_HOST=*4"
-          "PGRST_SERVER_PORT=3000"
-          "PGRST_OPENAPI_SERVER_PROXY_URI="
-          "PGRST_JWT_SECRET="
-          "PGRST_SECRET_IS_BASE64=false"
-          "PGRST_JWT_AUD="
-          "PGRST_MAX_ROWS="
-          "PGRST_PRE_REQUEST="
-          "PGRST_ROLE_CLAIM_KEY=.role"
-          "PGRST_ROOT_SPEC="
-          "PGRST_RAW_MEDIA_TYPES="
-        ];
+        Cmd = [ "/bin/postgrest" ];
         User = "1000";
         ExposedPorts = {
           "3000/tcp" = { };
@@ -65,4 +39,4 @@ buildEnv
   {
     name = "postgrest-docker";
     paths = [ load.bin ];
-  } // { inherit image config; }
+  } // { inherit image; }

nix/release/default.nix

@@ -94,17 +94,12 @@ let
             | ${jq}/bin/jq -r .token
         )"
 
-        # Plug the default config file into the full description.
-        defaultConfig="$(cat ${docker.config})"
-        export DEFAULT_CONFIG="$defaultConfig"
-        fullDescription="$(${envsubst}/bin/envsubst < ${fullDescription})"
-
-        # Patch the full description.
+        # Patch both descriptions.
         responseCode="$(
           ${curl}/bin/curl -s --write-out "%{response_code}" \
             --output /dev/null -H "Authorization: JWT $token" -X PATCH \
             --data-urlencode description@${description} \
-            --data-urlencode "full_description=$fullDescription" \
+            --data-urlencode full_description@${fullDescription} \
             "https://hub.docker.com/v2/repositories/$DOCKER_REPO/postgrest/"
         )"
 

nix/release/docker-hub-full-description.md

@@ -15,13 +15,8 @@ write from scratch.
 To learn how to use this container, see the [PostgREST Docker
 documentation](https://postgrest.com/en/stable/install.html#docker).
 
-You can configure the PostgREST image by setting the enviroment variables used
-in the default `/etc/postgrest.conf` file or overriding that file. This is the
-default configuration file:
-
-```
-$DEFAULT_CONFIG
-```
+You can configure the PostgREST image by setting
+[enviroment variables](https://postgrest.org/en/stable/configuration.html).
 
 # How this image is built