Adds a diagnostic startup message

CHANGELOG.adoc

@@ -4,13 +4,15 @@
 
 :262: https://github.com/stackabletech/agent/pull/262[#262]
 :267: https://github.com/stackabletech/agent/pull/267[#267]
+:270: https://github.com/stackabletech/agent/pull/270[#270]
 
 === Changed
 * Lazy validation of repository URLs changed to eager validation
   ({262}).
 * `certificates.k8s.io/v1` used instead of `certificates.k8s.io/v1beta1`
   so that the Stackable Agent is now compatible with Kubernetes v1.22
   but not any longer with versions prior to v1.19 ({267}).
+* Prints self-diagnostic information on startup ({270})
 
 == 0.5.0 - 2021-07-26
 

Cargo.toml

@@ -5,6 +5,7 @@ edition = "2018"
 license = "Apache-2.0"
 name = "stackable-agent"
 version = "0.6.0-nightly"
+build = "build.rs"
 
 [dependencies]
 # We are currently referencing the Krustlet directly from a Stackable fork of the official repository.
@@ -52,6 +53,9 @@ indoc = "1.0"
 rstest = "0.11"
 serde_yaml = "0.8"
 
+[build-dependencies]
+built = { version =  "0.5", features = ["chrono", "git2"] }
+
 [profile.release]
 opt-level = "s"
 lto = true

build.rs

@@ -0,0 +1,3 @@
+fn main() {
+    built::write_built_file().expect("Failed to acquire build-time information");
+}

src/bin/stackable-agent.rs

@@ -9,6 +9,29 @@ use stackable_config::ConfigBuilder;
 use stackable_agent::config::AgentConfig;
 use stackable_agent::provider::StackableProvider;
 
+mod built_info {
+    // The file has been placed there by the build script.
+    include!(concat!(env!("OUT_DIR"), "/built.rs"));
+}
+
+pub fn print_startup_string(
+    pkg_version: &str,
+    git_version: Option<&str>,
+    target: &str,
+    built_time: &str,
+    rustc_version: &str,
+) {
+    let git_information = match git_version {
+        None => "".to_string(),
+        Some(git) => format!(" (Git information: {})", git),
+    };
+    info!("Starting the Stackable Agent");
+    info!(
+        "This is version {}{}, built for {} by {} at {}",
+        pkg_version, git_information, target, rustc_version, built_time
+    )
+}
+
 #[tokio::main]
 async fn main() -> anyhow::Result<()> {
     // Initialize the logger
@@ -18,6 +41,15 @@ async fn main() -> anyhow::Result<()> {
         ConfigBuilder::build(env::args_os().collect::<Vec<OsString>>(), "CONFIG_FILE")
             .expect("Error initializing Configuration!");
 
+    // Make sure to only print diagnostic information once we are actually trying to start
+    print_startup_string(
+        built_info::PKG_VERSION,
+        built_info::GIT_VERSION,
+        built_info::TARGET,
+        built_info::BUILT_TIME_UTC,
+        built_info::RUSTC_VERSION,
+    );
+
     // Currently the only way to _properly_ configure the Krustlet is via these environment exports,
     // as their config object only offers methods that parse from command line flags (or combinations
     // of those flags with other things).