Output errors on a single line if backtraces are disabled (#1514)

* Output errors on a single line if ANSI output is disabled

* Add changelog entry

* Use published version of `oneline-eyre`

* Use oneline logs if RUST_BACKTRACE is unset, set to 0 or empty

* Use colored logs only if ANSI output is enabled

* Use value of RUST_BACKTRACE at runtime instead of compile time

* Simplify code

* Use single-line errors if backtraces are disabled even with a tty

.changelog/unreleased/improvements/ibc-relayer-cli/1515-single-line-errors.md

@@ -0,0 +1,2 @@
+- Output errors on a single line if ANSI output is disabled
+  ([#1515](https://github.com/informalsystems/ibc-rs/issues/1515))

relayer-cli/Cargo.toml

@@ -38,6 +38,7 @@ tracing = "0.1.29"
 tracing-subscriber = { version = "0.3.1", features = ["fmt", "env-filter", "json"]}
 eyre = "0.6.5"
 color-eyre = "0.5"
+oneline-eyre = "0.1"
 futures = "0.3.17"
 toml = "0.5.8"
 serde_derive = "1.0.116"

relayer-cli/src/bin/hermes/main.rs

@@ -6,11 +6,31 @@
 use ibc_relayer_cli::application::APPLICATION;
 use ibc_relayer_cli::components::enable_ansi;
 
-/// Boot Cli
 fn main() -> eyre::Result<()> {
-    if enable_ansi() {
-        color_eyre::install()?;
-    }
+    install_error_reporter()?;
 
     abscissa_core::boot(&APPLICATION);
 }
+
+fn install_error_reporter() -> eyre::Result<()> {
+    if !backtrace_enabled() {
+        // If backtraces are disabled, display errors in single line.
+        oneline_eyre::install()
+    } else if enable_ansi() {
+        // Else, if backtraces are enabled and we are in a terminal
+        // supporting color, display full error logs in color.
+        color_eyre::install()
+    } else {
+        // Otherwise, backtraces are enabled and we are piping to logs, so use the
+        // default error report handler, which displays multiline errors
+        // without color.
+        Ok(())
+    }
+}
+
+fn backtrace_enabled() -> bool {
+    match std::env::var("RUST_BACKTRACE").as_deref() {
+        Ok("" | "0") | Err(_) => false,
+        Ok(_) => true,
+    }
+}