refactor: do not pass entire config from CLI to core, send patch instead (#4598)

.changes/tauri-config-refactor.md

@@ -0,0 +1,8 @@
+---
+"cli.rs": patch
+"cli.js": patch
+"tauri-build": patch
+"tauri-codegen": patch
+---
+
+The `TAURI_CONFIG` environment variable now represents the configuration to be merged instead of the entire JSON.

core/tauri-build/Cargo.toml

@@ -24,6 +24,7 @@ tauri-utils = { version = "1.0.2", path = "../tauri-utils", features = [ "build"
 cargo_toml = "0.11"
 serde_json = "1"
 heck = "0.4"
+json-patch = "0.2"
 
 [target."cfg(windows)".dependencies]
 winres = "0.1"

core/tauri-build/src/lib.rs

@@ -185,13 +185,14 @@ pub fn try_build(attributes: Attributes) -> Result<()> {
   #[cfg(feature = "config-json5")]
   println!("cargo:rerun-if-changed=tauri.conf.json5");
 
-  let config: Config = if let Ok(env) = std::env::var("TAURI_CONFIG") {
-    serde_json::from_str(&env)?
-  } else {
-    serde_json::from_value(tauri_utils::config::parse::read_from(
-      std::env::current_dir().unwrap(),
-    )?)?
-  };
+  let mut config = serde_json::from_value(tauri_utils::config::parse::read_from(
+    std::env::current_dir().unwrap(),
+  )?)?;
+  if let Ok(env) = std::env::var("TAURI_CONFIG") {
+    let merge_config: serde_json::Value = serde_json::from_str(&env)?;
+    json_patch::merge(&mut config, &merge_config);
+  }
+  let config: Config = serde_json::from_value(config)?;
 
   cfg_alias("dev", !has_feature("custom-protocol"));
 

core/tauri-codegen/Cargo.toml

@@ -28,6 +28,7 @@ uuid = { version = "1", features = [ "v4" ] }
 semver = "1"
 ico = "0.1"
 png = "0.17"
+json-patch = "0.2"
 
 [target."cfg(target_os = \"macos\")".dependencies]
 plist = "1"

core/tauri-codegen/src/lib.rs

@@ -57,11 +57,12 @@ pub fn get_config(path: &Path) -> Result<(Config, PathBuf), CodegenConfigError>
   // it is impossible for the content of two separate configs to get mixed up. The chances are
   // already unlikely unless the developer goes out of their way to run the cli on a different
   // project than the target crate.
-  let config = if let Ok(env) = std::env::var("TAURI_CONFIG") {
-    serde_json::from_str(&env).map_err(CodegenConfigError::FormatInline)?
-  } else {
-    serde_json::from_value(tauri_utils::config::parse::read_from(parent.clone())?)?
-  };
+  let mut config = serde_json::from_value(tauri_utils::config::parse::read_from(parent.clone())?)?;
+  if let Ok(env) = std::env::var("TAURI_CONFIG") {
+    let merge_config: serde_json::Value =
+      serde_json::from_str(&env).map_err(CodegenConfigError::FormatInline)?;
+    json_patch::merge(&mut config, &merge_config);
+  }
 
-  Ok((config, parent))
+  Ok((serde_json::from_value(config)?, parent))
 }

examples/api/src-tauri/Cargo.lock

@@ -3199,6 +3199,7 @@ dependencies = [
  "anyhow",
  "cargo_toml",
  "heck 0.4.0",
+ "json-patch",
  "semver 1.0.10",
  "serde_json",
  "tauri-codegen",
@@ -3213,6 +3214,7 @@ dependencies = [
  "base64",
  "brotli",
  "ico",
+ "json-patch",
  "plist",
  "png 0.17.5",
  "proc-macro2",

tooling/cli/src/helpers/config.rs

@@ -118,6 +118,7 @@ fn get_internal(merge_config: Option<&str>, reload: bool) -> crate::Result<Confi
   }
 
   if let Some(merge_config) = merge_config {
+    set_var("TAURI_CONFIG", merge_config);
     let merge_config: JsonValue =
       serde_json::from_str(merge_config).with_context(|| "failed to parse config to merge")?;
     merge(&mut config, &merge_config);
@@ -145,7 +146,6 @@ fn get_internal(merge_config: Option<&str>, reload: bool) -> crate::Result<Confi
   }
 
   let config: Config = serde_json::from_value(config)?;
-  set_var("TAURI_CONFIG", serde_json::to_string(&config)?);
 
   *config_handle().lock().unwrap() = Some(ConfigMetadata {
     inner: config,