Drop vergen dependency

We only need the version, build time, rust target triple, and git commit
for the version command. These values can easily be generated with little
code so we do not need an extra dependency for this.

The main reason for this change is that vergen will fail if no git
commit is found. On distro build systems this is often the case since
they build from a source tar without the git repo. Instead of erroring
we should just show an empty commit in the version output.

Fixes #247

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

Cargo.toml

@@ -38,5 +38,4 @@ sha2 = "0.10.1"
 netlink-packet-route = "0.11"
 
 [build-dependencies]
-vergen = { version = "6.0.2", default-features = false, features = ["build", "rustc", "git"] }
-anyhow = "1.0"
+chrono = "*"

build.rs

@@ -1,7 +1,26 @@
-use anyhow::Result;
-use vergen::{vergen, Config};
+use chrono::Utc;
+use std::process::Command;
 
-fn main() -> Result<()> {
+fn main() {
     // Generate the default 'cargo:' instruction output
-    vergen(Config::default())
+    println!("cargo:rerun-if-changed=build.rs");
+
+    // get timestamp
+    let now = Utc::now();
+    println!("cargo:rustc-env=BUILD_TIMESTAMP={}", now.to_rfc3339());
+
+    // get rust target triple from TARGET env
+    println!(
+        "cargo:rustc-env=BUILD_TARGET={}",
+        std::env::var("TARGET").unwrap()
+    );
+
+    // get git commit
+    let command = Command::new("git").args(&["rev-parse", "HEAD"]).output();
+    let commit = match command {
+        Ok(output) => String::from_utf8(output.stdout).unwrap(),
+        // if error, e.g. build from source with git repo, just show empty string
+        Err(_) => "".to_string(),
+    };
+    println!("cargo:rustc-env=GIT_COMMIT={}", commit);
 }

src/commands/version.rs

@@ -17,10 +17,10 @@ struct Info {
 impl Version {
     pub fn exec(&self) -> Result<(), Box<dyn Error>> {
         let info = Info {
-            version: env!("VERGEN_BUILD_SEMVER"),
-            commit: env!("VERGEN_GIT_SHA"),
-            build_time: env!("VERGEN_BUILD_TIMESTAMP"),
-            target: env!("VERGEN_RUSTC_HOST_TRIPLE"),
+            version: env!("CARGO_PKG_VERSION"),
+            commit: env!("GIT_COMMIT"),
+            build_time: env!("BUILD_TIMESTAMP"),
+            target: env!("BUILD_TARGET"),
         };
 
         let out = serde_json::to_string_pretty(&info)?;

src/main.rs

@@ -5,7 +5,7 @@ use netavark::commands::teardown;
 use netavark::commands::version;
 
 #[derive(Parser, Debug)]
-#[clap(version = env!("VERGEN_BUILD_SEMVER"))]
+#[clap(version = env!("CARGO_PKG_VERSION"))]
 struct Opts {
     /// Instead of reading from STDIN, read the configuration to be applied from the given file.
     #[clap(short, long)]