Add conditional compilation to early-boot-config

This change adds a simple solution for conditionally compiling
early-boot-config based on the current variant.  As part of the change,
local file handling (which was previously broken) is split into its own
trait implementation and only compiled into the program for "aws-dev"
variants.  We also add the ability to read a mounted cdrom for user
data.

sources/api/early-boot-config/Cargo.toml

@@ -11,11 +11,13 @@ exclude = ["README.md"]
 
 [dependencies]
 apiclient = { path = "../apiclient" }
+base64 = "0.13"
 http = "0.2"
 log = "0.4"
 reqwest = { version = "0.10", default-features = false, features = ["blocking"] }
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1"
+serde-xml-rs = "0.4.1"
 simplelog = "0.9"
 snafu = "0.6"
 tokio = { version = "0.2", default-features = false, features = ["macros", "rt-threaded"] }

sources/api/early-boot-config/build.rs

@@ -4,8 +4,31 @@ use std::env;
 use std::fs::File;
 use std::io::Write;
 use std::path::PathBuf;
+use std::process;
 
 fn main() {
+    // The code below emits `cfg` operators to conditionally compile this program based on the
+    // current variant.
+    // TODO: Replace this approach when the build system supports ideas like "variant
+    // tags": https://github.com/bottlerocket-os/bottlerocket/issues/1260
+    println!("cargo:rerun-if-env-changed=VARIANT");
+    if let Ok(variant) = env::var("VARIANT") {
+        if variant == "aws-dev" {
+            println!("cargo:rustc-cfg=bottlerocket_platform=\"aws-dev\"");
+        } else if variant.starts_with("aws") {
+            println!("cargo:rustc-cfg=bottlerocket_platform=\"aws\"");
+        } else if variant.starts_with("vmware") {
+            println!("cargo:rustc-cfg=bottlerocket_platform=\"vmware\"");
+        } else {
+            eprintln!(
+            "For local builds, you must set the 'VARIANT' environment variable so we know which data \
+            provider to build. Valid values are the directories in models/src/variants/, for \
+            example 'aws-k8s-1.17'."
+            );
+            process::exit(1);
+        }
+    }
+
     // Check for environment variable "SKIP_README". If it is set,
     // skip README generation
     if env::var_os("SKIP_README").is_some() {