feat(hermit-image-reader): config versioning

Author: fogti

hermit-image-reader/src/config.rs

@@ -3,16 +3,21 @@ use alloc::{string::String, vec::Vec};
 pub const DEFAULT_CONFIG_NAME: &str = "hermit_config.toml";
 pub type ParserError = toml::de::Error;
 
-#[derive(Clone, Debug, PartialEq, serde::Deserialize, serde::Serialize)]
 /// The image `hermit_config.toml` config file format.
 ///
 /// All file paths are relative to the iamge root.
-pub struct Config {
-	pub input: Input,
-	pub requirements: Requirements,
-
-	pub kernel: String,
-	pub mount_point: String,
+#[derive(Clone, Debug, PartialEq, serde::Deserialize, serde::Serialize)]
+#[serde(tag = "version")]
+pub enum Config {
+	#[serde(rename = "1")]
+	V1 {
+		input: Input,
+		#[serde(default)]
+		requirements: Requirements,
+
+		kernel: String,
+		mount_point: String,
+	},
 }
 
 #[derive(Clone, Debug, PartialEq, serde::Deserialize, serde::Serialize)]
@@ -27,7 +32,7 @@ pub struct Input {
 	pub env_vars: Vec<String>,
 }
 
-#[derive(Clone, Debug, PartialEq, serde::Deserialize, serde::Serialize)]
+#[derive(Clone, Debug, Default, PartialEq, serde::Deserialize, serde::Serialize)]
 pub struct Requirements {
 	pub memory: Option<byte_unit::Byte>,
 

src/vm.rs

@@ -160,7 +160,7 @@ impl<VirtBackend: VirtualizationBackend> UhyveVm<VirtBackend> {
 						error!("Hermit image doesn't contain configuration file");
 						HypervisorError::InvalidKernelPath(kernel_path.clone())
 					})?;
-				let mut config = if let HermitImageThinTree::File(f) = config {
+				let config = if let HermitImageThinTree::File(f) = config {
 					hermit_image_reader::config::parse(f).map_err(|e| {
 						error!("Hermit image configuration is invalid: {}", e);
 						HypervisorError::ImageConfigParserError(e)
@@ -170,65 +170,68 @@ impl<VirtBackend: VirtualizationBackend> UhyveVm<VirtBackend> {
 					return Err(HypervisorError::InvalidKernelPath(kernel_path.clone()));
 				};
 
-				// handle image configuration
+				match config {
+					hermit_image_reader::config::Config::V1 { mut input, requirements: _, kernel, mount_point } => {
+						// handle image configuration
+
+						// .input
+						if params.kernel_args.is_empty() {
+							params.kernel_args.append(&mut input.kernel_args);
+							if !input.app_args.is_empty() {
+								params.kernel_args.push("--".to_string());
+								params.kernel_args.append(&mut input.app_args);
+							}
+						}
 
-				// .input
-				if params.kernel_args.is_empty() {
-					params.kernel_args.append(&mut config.input.kernel_args);
-					if !config.input.app_args.is_empty() {
-						params.kernel_args.push("--".to_string());
-						params.kernel_args.append(&mut config.input.app_args);
-					}
-				}
+						// don't pass privileged env-var commands through
+						input.env_vars.retain(|i| i.contains('='));
+
+						if let EnvVars::Set(env) = &mut params.env {
+							if let Ok(EnvVars::Set(prev_env_vars)) =
+								EnvVars::try_from(&input.env_vars[..])
+							{
+								// env vars from params take precedence
+								let new_env_vars = core::mem::take(env);
+								*env = prev_env_vars.into_iter().chain(new_env_vars).collect();
+							} else {
+								warn!("Unable to parse env vars from Hermit image configuration");
+							}
+						} else if !input.env_vars.is_empty() {
+							warn!("Ignoring Hermit image env vars due to `-e host`");
+						}
 
-				// don't pass privileged env-var commands through
-				config.input.env_vars.retain(|i| i.contains('='));
-
-				if let EnvVars::Set(env) = &mut params.env {
-					if let Ok(EnvVars::Set(prev_env_vars)) =
-						EnvVars::try_from(&config.input.env_vars[..])
-					{
-						// env vars from params take precedence
-						let new_env_vars = core::mem::take(env);
-						*env = prev_env_vars.into_iter().chain(new_env_vars).collect();
-					} else {
-						warn!("Unable to parse env vars from Hermit image configuration");
+						// .requirements
+						// TODO: implement this part
+
+						// Limitation of current implementation:
+						//   because we need to put the image path into the file map,
+						//   it needs to be valid UTF-8
+						let image_path_str = kernel_path
+							.to_str()
+							.expect("path to image must be valid UTF-8");
+
+						// .mount_point
+						params
+							.file_mapping
+							.insert(0, format!("{}::{}", image_path_str, mount_point));
+
+						// .kernel
+						if let HermitImageThinTree::File(f) = image_tree
+							.get()
+							.resolve((*kernel).into())
+							.ok_or_else(|| {
+								HypervisorError::InvalidKernelPath(PathBuf::from(format!(
+									"{}:{}",
+									image_path_str, &kernel
+								)))
+							})? {
+							f.to_vec()
+						} else {
+							return Err(HypervisorError::InvalidKernelPath(PathBuf::from(
+								format!("{}:{}", image_path_str, &kernel),
+							)));
+						}
 					}
-				} else if !config.input.env_vars.is_empty() {
-					warn!("Ignoring Hermit image env vars due to `-e host`");
-				}
-
-				// .requirements
-				// TODO: implement this part
-
-				// Limitation of current implementation:
-				//   because we need to put the image path into the file map,
-				//   it needs to be valid UTF-8
-				let image_path_str = kernel_path
-					.to_str()
-					.expect("path to image must be valid UTF-8");
-
-				// .mount_point
-				params
-					.file_mapping
-					.insert(0, format!("{}::{}", image_path_str, config.mount_point));
-
-				// .kernel
-				if let HermitImageThinTree::File(f) = image_tree
-					.get()
-					.resolve((*config.kernel).into())
-					.ok_or_else(|| {
-						HypervisorError::InvalidKernelPath(PathBuf::from(format!(
-							"{}:{}",
-							image_path_str, &config.kernel
-						)))
-					})? {
-					f.to_vec()
-				} else {
-					return Err(HypervisorError::InvalidKernelPath(PathBuf::from(format!(
-						"{}:{}",
-						image_path_str, &config.kernel
-					))));
 				}
 			}
 		};