early-boot-config: Simplify conditional compilation and make local_file available to all platforms

sources/api/early-boot-config/src/main.rs

@@ -24,7 +24,7 @@ use std::{env, process};
 mod compression;
 mod provider;
 mod settings;
-use crate::provider::PlatformDataProvider;
+use crate::provider::{Platform, PlatformDataProvider};
 
 // TODO
 // Tests!
@@ -40,30 +40,6 @@ const TRANSACTION: &str = "bottlerocket-launch";
 // We create it after running successfully.
 const MARKER_FILE: &str = "/var/lib/bottlerocket/early-boot-config.ran";
 
-/// This function returns the appropriate data provider for this variant. It exists primarily to
-/// keep the ugly bits of conditional compilation out of the main function.
-fn create_provider() -> Result<Box<dyn PlatformDataProvider>> {
-    #[cfg(bottlerocket_platform = "aws")]
-    {
-        Ok(Box::new(provider::aws::AwsDataProvider))
-    }
-
-    #[cfg(bottlerocket_platform = "aws-dev")]
-    {
-        use std::path::Path;
-        if Path::new(provider::local_file::LocalFileDataProvider::USER_DATA_FILE).exists() {
-            Ok(Box::new(provider::local_file::LocalFileDataProvider))
-        } else {
-            Ok(Box::new(provider::aws::AwsDataProvider))
-        }
-    }
-
-    #[cfg(bottlerocket_platform = "vmware")]
-    {
-        Ok(Box::new(provider::vmware::VmwareDataProvider))
-    }
-}
-
 /// Store the args we receive on the command line
 #[derive(Debug)]
 struct Args {
@@ -134,13 +110,10 @@ async fn run() -> Result<()> {
 
     info!("early-boot-config started");
 
-    // Figure out the current provider
-    let data_provider = create_provider()?;
-
     info!("Retrieving platform-specific data");
     let uri = &format!("{}?tx={}", API_SETTINGS_URI, TRANSACTION);
     let method = "PATCH";
-    for settings_json in data_provider
+    for settings_json in Platform
         .platform_data()
         .await
         .context(error::ProviderError)?

sources/api/early-boot-config/src/provider.rs

@@ -3,14 +3,18 @@
 use crate::settings::SettingsJson;
 use async_trait::async_trait;
 
-#[cfg(any(bottlerocket_platform = "aws", bottlerocket_platform = "aws-dev"))]
-pub(crate) mod aws;
-
 #[cfg(bottlerocket_platform = "aws-dev")]
-pub(crate) mod local_file;
+mod local_file;
+
+#[cfg(any(bottlerocket_platform = "aws", bottlerocket_platform = "aws-dev"))]
+mod aws;
+#[cfg(any(bottlerocket_platform = "aws", bottlerocket_platform = "aws-dev"))]
+pub(crate) use aws::AwsDataProvider as Platform;
 
 #[cfg(bottlerocket_platform = "vmware")]
-pub(crate) mod vmware;
+mod vmware;
+#[cfg(bottlerocket_platform = "vmware")]
+pub(crate) use vmware::VmwareDataProvider as Platform;
 
 /// Support for new platforms can be added by implementing this trait.
 #[async_trait]

sources/api/early-boot-config/src/provider/aws.rs

@@ -9,6 +9,9 @@ use snafu::{OptionExt, ResultExt};
 use std::fs;
 use std::path::Path;
 
+#[cfg(bottlerocket_platform = "aws-dev")]
+use crate::provider::local_file::{local_file_user_data, USER_DATA_FILE};
+
 /// Unit struct for AWS so we can implement the PlatformDataProvider trait.
 pub(crate) struct AwsDataProvider;
 
@@ -82,7 +85,16 @@ impl PlatformDataProvider for AwsDataProvider {
 
         let mut client = ImdsClient::new().await.context(error::ImdsClient)?;
 
-        // Instance identity doc first, so the user has a chance to override
+        // Attempt to read from local file first on the `aws-dev` variant
+        #[cfg(bottlerocket_platform = "aws-dev")]
+        {
+            match local_file_user_data()? {
+                None => warn!("No user data found via local file: {}", USER_DATA_FILE),
+                Some(s) => output.push(s),
+            }
+        }
+
+        // Instance identity doc next, so the user has a chance to override
         match Self::identity_document(&mut client).await? {
             None => warn!("No instance identity document found."),
             Some(s) => output.push(s),

sources/api/early-boot-config/src/provider/local_file.rs

@@ -1,42 +1,35 @@
-//! The local_file module implements the `PlatformDataProvider` trait for gathering userdata from
-//! local file
+//! The local_file module provides a method for gathering userdata from local file
 
-use super::{PlatformDataProvider, SettingsJson};
+use super::SettingsJson;
 use crate::compression::expand_file_maybe;
-use async_trait::async_trait;
 use snafu::ResultExt;
+use std::path::Path;
 
-pub(crate) struct LocalFileDataProvider;
+pub(crate) const USER_DATA_FILE: &'static str = "/etc/early-boot-config/user-data";
 
-impl LocalFileDataProvider {
-    pub(crate) const USER_DATA_FILE: &'static str = "/etc/early-boot-config/user-data";
-}
+pub(crate) fn local_file_user_data(
+) -> std::result::Result<Option<SettingsJson>, Box<dyn std::error::Error>> {
+    if !Path::new(USER_DATA_FILE).exists() {
+        return Ok(None);
+    }
+    info!("'{}' exists, using it", USER_DATA_FILE);
+
+    // Read the file, decompressing it if compressed.
+    let user_data_str = expand_file_maybe(USER_DATA_FILE).context(error::InputFileRead {
+        path: USER_DATA_FILE,
+    })?;
 
-#[async_trait]
-impl PlatformDataProvider for LocalFileDataProvider {
-    async fn platform_data(&self) -> std::result::Result<Vec<SettingsJson>, Box<dyn std::error::Error>> {
-        let mut output = Vec::new();
-        info!("'{}' exists, using it", Self::USER_DATA_FILE);
-
-        // Read the file, decompressing it if compressed.
-        let user_data_str =
-            expand_file_maybe(Self::USER_DATA_FILE).context(error::InputFileRead {
-                path: Self::USER_DATA_FILE,
-            })?;
-
-        if user_data_str.is_empty() {
-            return Ok(output);
-        }
-
-        let json = SettingsJson::from_toml_str(&user_data_str, "user data").context(
-            error::SettingsToJSON {
-                from: Self::USER_DATA_FILE,
-            },
-        )?;
-        output.push(json);
-
-        Ok(output)
+    if user_data_str.is_empty() {
+        return Ok(None);
     }
+
+    let json = SettingsJson::from_toml_str(&user_data_str, "user data").context(
+        error::SettingsToJSON {
+            from: USER_DATA_FILE,
+        },
+    )?;
+
+    Ok(Some(json))
 }
 
 mod error {