Just exit normally when booted into a container

The previous work resulted in an error, but let's just
exit with status zero because otherwise we end up tripping up
things like checks for failing units.

Anyone who has rebased into a container has very clearly
taken explicit control over the wheel and there's no
point in us erroring out.

Closes: coreos#859

dist/systemd/system/zincati.service

@@ -21,8 +21,6 @@ Environment=ZINCATI_VERBOSITY="-v"
 Type=notify
 ExecStart=/usr/libexec/zincati agent ${ZINCATI_VERBOSITY}
 Restart=on-failure
-# This status signals a non-restartable condition
-RestartPreventExitStatus=7
 RestartSec=10s
 
 [Install]

src/main.rs

@@ -58,10 +58,10 @@ fn run() -> i32 {
         Err(e) => {
             log_error_chain(&e);
             if e.root_cause()
-                .downcast_ref::<crate::rpm_ostree::FatalError>()
+                .downcast_ref::<crate::rpm_ostree::SystemInoperable>()
                 .is_some()
             {
-                7
+                0
             } else {
                 libc::EXIT_FAILURE
             }

src/rpm_ostree/cli_status.rs

@@ -39,15 +39,15 @@ lazy_static::lazy_static! {
 
 /// An error which should not result in a retry/restart.
 #[derive(Debug, Clone)]
-pub struct FatalError(String);
+pub struct SystemInoperable(String);
 
-impl std::fmt::Display for FatalError {
+impl std::fmt::Display for SystemInoperable {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         self.0.fmt(f)
     }
 }
 
-impl std::error::Error for FatalError {}
+impl std::error::Error for SystemInoperable {}
 
 /// JSON output from `rpm-ostree status --json`
 #[derive(Clone, Debug, Deserialize)]
@@ -101,8 +101,9 @@ pub fn parse_booted(status: &Status) -> Result<Release> {
     let status = booted_status(status)?;
     if let Some(img) = status.container_image_reference.as_ref() {
         let msg = format!("Automatic updates disabled; booted into container image {img}");
+        crate::utils::notify_ready();
         crate::utils::update_unit_status(&msg);
-        return Err(anyhow::Error::new(FatalError(msg)));
+        return Err(anyhow::Error::new(SystemInoperable(msg)));
     }
     Ok(status.into_release())
 }

src/rpm_ostree/mod.rs

@@ -1,7 +1,9 @@
 mod cli_deploy;
 mod cli_finalize;
 mod cli_status;
-pub use cli_status::{invoke_cli_status, parse_booted, parse_booted_updates_stream, FatalError};
+pub use cli_status::{
+    invoke_cli_status, parse_booted, parse_booted_updates_stream, SystemInoperable,
+};
 
 mod actor;
 pub use actor::{