ci: use env variables to get git commit hash in CI

crates/notary/server/build.rs

@@ -1,21 +1,25 @@
-use std::process::Command;
+use std::{env, process::Command};
 
 fn main() {
-    // Used to extract latest HEAD commit hash and timestamp for the /info endpoint
-    let output = Command::new("git")
-        .args(["show", "HEAD", "-s", "--format=%H,%cI"])
-        .output()
-        .expect("Git command to get commit hash and timestamp should work during build process");
+    if env::var("GIT_COMMIT_HASH").is_err() || env::var("GIT_COMMIT_TIMESTAMP").is_err() {
+        // Used to extract latest HEAD commit hash and timestamp for the /info endpoint
+        let output = Command::new("git")
+            .args(["show", "HEAD", "-s", "--format=%H,%cI"])
+            .output()
+            .expect(
+                "Git command to get commit hash and timestamp should work during build process",
+            );
 
-    let output_string =
-        String::from_utf8(output.stdout).expect("Git command should produce valid string output");
+        let output_string = String::from_utf8(output.stdout)
+            .expect("Git command should produce valid string output");
 
-    let (commit_hash, commit_timestamp) = output_string
-        .as_str()
-        .split_once(',')
-        .expect("Git commit hash and timestamp string output should be comma separated");
+        let (commit_hash, commit_timestamp) = output_string
+            .as_str()
+            .split_once(',')
+            .expect("Git commit hash and timestamp string output should be comma separated");
 
-    // Pass these 2 values as env var to the program
-    println!("cargo:rustc-env=GIT_COMMIT_HASH={}", commit_hash);
-    println!("cargo:rustc-env=GIT_COMMIT_TIMESTAMP={}", commit_timestamp);
+        // Pass these 2 values as env var to the program
+        println!("cargo:rustc-env=GIT_COMMIT_HASH={}", commit_hash);
+        println!("cargo:rustc-env=GIT_COMMIT_TIMESTAMP={}", commit_timestamp);
+    }
 }