feat: dry-run operation for validation only

Signed-off-by: Lincoln Wallace <lincoln.wallace@canonical.com>

extensions/env-injector/src/main.rs

@@ -4,6 +4,7 @@ use hyper::{Method, Request};
 use hyper_util::client::legacy::Client;
 use hyperlocal::{UnixClientExt, UnixConnector, Uri};
 use std::error::Error;
+use std::fmt::format;
 use std::process::Command;
 use std::collections::HashMap;
 use std::path::Path;
@@ -19,7 +20,7 @@ async fn snapdapi_req() -> Result<serde_json::Value, Box<dyn Error + Send + Sync
     let snap_context = std::env::var("SNAP_CONTEXT")?;
 
     let request_body = format!(
-        r#"{{"context-id":"{}","args":["get","env", "envfile", "apps"]}}"#,
+        r#"{{"context-id":"{}","args":["get", "env", "envfile", "apps"]}}"#,
         snap_context
     );
 
@@ -74,17 +75,6 @@ fn set_env_vars(app: &str, json: &serde_json::Value) -> Result<(), Box<dyn std::
 }
 
 fn source_env_file(file_path: &str) -> std::io::Result<HashMap<String, String>> {
-    let path = Path::new(file_path);
-
-    if !path.exists() {
-        eprintln!("File does not exist: {}", file_path);
-        return Err(std::io::Error::new(std::io::ErrorKind::NotFound, "File does not exist"));
-    }
-
-    if !path.is_file() {
-        eprintln!("File is not readable: {}", file_path);
-        return Err(std::io::Error::new(std::io::ErrorKind::PermissionDenied, "File is not readable"));
-    }
 
     let file = std::fs::File::open(file_path)?;
     let reader = std::io::BufReader::new(file);
@@ -128,16 +118,55 @@ fn set_env_vars_from_file(app: &str, json: &serde_json::Value) ->  Result<(), Bo
     Ok(())
 }
 
+
+fn validate(json: &serde_json::Value) -> Result<(), Box<dyn Error + Send + Sync>> {
+
+    if let Some(global_envfile) = json["envfile"].as_str() {
+        file_validation(global_envfile)?;
+    }
+
+    if let Some(app_envfile) = json["apps"]["envfile"].as_str() {
+        file_validation(app_envfile)?;
+    }
+
+    Ok(())
+}
+
+fn file_validation(file_path: &str) ->  std::io::Result<()> {
+    let path = Path::new(&file_path);
+
+    if !path.exists() {
+        let err = format!("File does not exist: {}", file_path);
+        eprintln!("{}", &err);
+        return Err(std::io::Error::new(std::io::ErrorKind::NotFound, err, ));
+    }
+
+    if !path.is_file() {
+        let err = format!("File is not readable: {}", file_path);
+        eprintln!("{}", &err);
+        return Err(std::io::Error::new(std::io::ErrorKind::PermissionDenied, err));
+    }
+
+    Ok(())
+}
+
+
+
 #[tokio::main]
 async fn run() -> Result<(), Box<dyn Error + Send + Sync>> {
 
+    let dryrun = std::env::var("DRY_RUN").is_ok();
+
     let json = snapdapi_req().await?;
 
     let app = std::env::var("env_alias")?;
 
-    set_env_vars_from_file(&app, &json)?;
-    set_env_vars(&app, &json)?;
+    validate(&json)?;
 
+    if !dryrun {
+        set_env_vars_from_file(&app, &json)?;
+        set_env_vars(&app, &json)?;
+    }
     Ok(())
 }
 

snapcraft/extensions/env_injector.py

@@ -71,10 +71,13 @@ def get_root_snippet(self) -> Dict[str, Any]:
 
 
     @overrides
-    def get_app_snippet(self) -> Dict[str, Any]:
+    def get_app_snippet(self, *, app_name: str) -> Dict[str, Any]:
         """Return the app snippet to apply."""
         return {
             "command-chain": [ "bin/command-chain/env-exporter"],
+            "environment": {
+                "env_alias": f"{app_name}",
+            }
         }
 
     @overrides
@@ -90,7 +93,7 @@ def get_parts_snippet(self) -> Dict[str, Any]:
         toolchain = self.get_toolchain()
         return {
             f"env-injector/env-injector": {
-                "source": f"{get_extensions_data_dir()}/envs",
+                "source": f"{get_extensions_data_dir()}/env-injector",
                 "plugin": "nil",
                 "build-snaps": [
                     f"rustup",