improved tedge-write related logging

Put more details into warn and error logs when deploying configuration
files using `tedge-write`:

- before: "WARN: `sudo.enable` set to `true`, but sudo not found in $PATH"
- after:  "WARN: `sudo.enable` set to `true`, but sudo not found in $PATH, using tedge-write directly"

- before: "ERROR: config-manager failed writing updated configuration file: Starting tedge-write process failed"
- after:  "ERROR: config-manager failed writing updated configuration file: failed to start process '/usr/bin/tedge-write': No such file or directory (os error 2)"

- before: "ERROR: config-manager failed writing updated configuration file: sudo: /usr/bin/tedge-write: command not found"
- after:  "ERROR: config-manager failed writing updated configuration file: process returned non-zero exit code (1); stderr="sudo: /usr/bin/tedge-write: command not found""

Signed-off-by: Marcel Guzik <[email protected]>

crates/common/tedge_config/src/sudo.rs

@@ -57,7 +57,7 @@ impl SudoCommandBuilder {
                 c
             }
             Err(_) => {
-                warn!("`sudo.enable` set to `true`, but sudo not found in $PATH");
+                warn!("`sudo.enable` set to `true`, but sudo not found in $PATH, using tedge-write directly");
                 Command::new(program)
             }
         }

crates/core/tedge_write/src/api.rs

@@ -33,24 +33,30 @@ impl<'a> CopyOptions<'a> {
     ///
     /// Stdin and Stdout are UTF-8.
     pub fn copy(self) -> anyhow::Result<()> {
-        let output = self
-            .command()?
-            .output()
-            .context("Starting tedge-write process failed")?;
+        let mut command = self.command()?;
+
+        let output = command.output();
+
+        let program = command.get_program().to_string_lossy();
+        let output = output.with_context(|| format!("failed to start process '{program}'"))?;
 
         if !output.status.success() {
+            let stderr = String::from_utf8(output.stderr).expect("output should be utf-8");
+            let stderr = stderr.trim();
+            let exit_code = output.status.code().unwrap();
             return Err(anyhow!(
-                String::from_utf8(output.stderr).expect("output should be utf-8")
+                "process returned non-zero exit code ({exit_code}); stderr=\"{stderr}\""
             ));
         }
 
         Ok(())
     }
 
-    fn command(&self) -> std::io::Result<Command> {
+    fn command(&self) -> anyhow::Result<Command> {
         let mut command = self.sudo.command(crate::TEDGE_WRITE_PATH);
 
-        let from_reader = std::fs::File::open(self.from)?;
+        let from_reader = std::fs::File::open(self.from)
+            .with_context(|| format!("could not open file for reading '{}'", self.from))?;
         command.stdin(from_reader).arg(self.to);
 
         if let Some(mode) = self.mode {

crates/extensions/tedge_config_manager/src/error.rs

@@ -35,7 +35,7 @@ pub enum ConfigManagementError {
     #[error(transparent)]
     FromAtomFileError(#[from] tedge_utils::fs::AtomFileError),
 
-    #[error(transparent)]
+    #[error("{0:#}")]
     Other(#[from] anyhow::Error),
 }