status: Drop nanoseconds from time

This is just irrelevant noise; nanoseconds never matter for container
builds. Motivated by just making this look visually nicer.

In the future I'd like to look at rendering this how e.g. systemd
does it also including a "; 1 day ago" humantime suffix.

Signed-off-by: Colin Walters <[email protected]>

Author: cgwalters

lib/src/fixtures/spec-staged-booted.yaml

@@ -15,7 +15,8 @@ status:
         transport: registry
         signature: insecure
       version: nightly
-      timestamp: 2023-10-14T19:22:15Z
+      # This one has nanoseconds, which should be dropped for human consumption
+      timestamp: 2023-10-14T19:22:15.42Z
       imageDigest: sha256:16dc2b6256b4ff0d2ec18d2dbfb06d117904010c8cf9732cdb022818cf7a7566
     incompatible: false
     pinned: false

lib/src/status.rs

@@ -379,7 +379,13 @@ fn human_render_imagestatus(
     let digest = &image.image_digest;
     writeln!(out, "{digest}")?;
 
-    let timestamp = image.timestamp.as_ref();
+    // Format the timestamp without nanoseconds since those are just irrelevant noise for human
+    // consumption - that time scale should basically never matter for container builds.
+    let timestamp = image
+        .timestamp
+        .as_ref()
+        // This format is the same as RFC3339, just without nanos.
+        .map(|t| t.to_utc().format("%Y-%m-%dT%H:%M:%SZ"));
     // If we have a version, combine with timestamp
     if let Some(version) = image.version.as_deref() {
         write_row_name(&mut out, "Version", prefix_len)?;
@@ -466,11 +472,11 @@ mod tests {
         let expected = indoc::indoc! { r"
             Staged image: quay.io/example/someimage:latest
                   Digest: sha256:16dc2b6256b4ff0d2ec18d2dbfb06d117904010c8cf9732cdb022818cf7a7566
-                 Version: nightly (2023-10-14 19:22:15 UTC)
+                 Version: nightly (2023-10-14T19:22:15Z)
         
           ● Booted image: quay.io/example/someimage:latest
                   Digest: sha256:736b359467c9437c1ac915acaae952aad854e07eb4a16a94999a48af08c83c34
-                 Version: nightly (2023-09-30 19:22:16 UTC)
+                 Version: nightly (2023-09-30T19:22:16Z)
         "};
         similar_asserts::assert_eq!(w, expected);
     }