Allow forcing `zebrad` to use color output (#3547)

* Allow forcing colored output in `zebrad`

Add a configuration item that allows forcing Zebra to output in color
mode even if the output device is not a terminal.

* Allow enabling colored output from Zebra in tests

Force Zebrad instances to use colored output if the
`ZEBRA_FORCE_USE_COLOR` environment variable is set.

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

zebrad/src/components/tracing/component.rs

@@ -21,8 +21,10 @@ impl Tracing {
         let filter = config.filter.unwrap_or_else(|| "".to_string());
         let flame_root = &config.flamegraph;
 
-        // Only use color if tracing output is being sent to a terminal
-        let use_color = config.use_color && atty::is(atty::Stream::Stdout);
+        // Only use color if tracing output is being sent to a terminal or if it was explicitly
+        // forced to.
+        let use_color =
+            config.force_use_color || (config.use_color && atty::is(atty::Stream::Stdout));
 
         // Construct a tracing subscriber with the supplied filter and enable reloading.
         let builder = FmtSubscriber::builder()

zebrad/src/config.rs

@@ -57,6 +57,14 @@ pub struct TracingSection {
     /// terminals.
     pub use_color: bool,
 
+    /// Whether to force the use of colored terminal output, even if it's not available.
+    ///
+    /// Will force Zebra to use colored terminal output even if it does not detect that the output
+    /// is a terminal that supports colors.
+    ///
+    /// Defaults to `false`, which keeps the behavior of `use_color`.
+    pub force_use_color: bool,
+
     /// The filter used for tracing events.
     ///
     /// The filter is used to create a `tracing-subscriber`
@@ -120,6 +128,7 @@ impl Default for TracingSection {
     fn default() -> Self {
         Self {
             use_color: true,
+            force_use_color: false,
             filter: None,
             endpoint_addr: None,
             flamegraph: None,

zebrad/tests/acceptance.rs

@@ -42,7 +42,7 @@ use zebra_test::{
 };
 use zebrad::{
     components::{mempool, sync},
-    config::{SyncSection, ZebradConfig},
+    config::{SyncSection, TracingSection, ZebradConfig},
 };
 
 /// The amount of time we wait after launching `zebrad`.
@@ -82,12 +82,22 @@ fn default_test_config() -> Result<ZebradConfig> {
         ..zebra_consensus::Config::default()
     };
 
+    let force_use_color = !matches!(
+        env::var("ZEBRA_FORCE_USE_COLOR"),
+        Err(env::VarError::NotPresent)
+    );
+    let tracing = TracingSection {
+        force_use_color,
+        ..TracingSection::default()
+    };
+
     let config = ZebradConfig {
         network,
         state: zebra_state::Config::ephemeral(),
         sync,
         mempool,
         consensus,
+        tracing,
         ..ZebradConfig::default()
     };