print a Zebra logo and some text if stderr is terminal (#6945)

* print a Zebra logo and some text in progress bar mode

* add network to printed line, add heart to logo

* print logo and message regardless of progress-bar; document how logo was generated

zebrad/src/application.rs

@@ -419,7 +419,10 @@ impl Application for ZebradApp {
             tracing_config.filter = Some(default_filter.to_owned());
             tracing_config.flamegraph = None;
         }
-        components.push(Box::new(Tracing::new(tracing_config)?));
+        components.push(Box::new(Tracing::new(
+            config.network.network,
+            tracing_config,
+        )?));
 
         // Log git metadata and platform info when zebrad starts up
         if is_server {

zebrad/src/components/tracing.rs

@@ -138,6 +138,12 @@ impl Config {
         self.force_use_color || (self.use_color && atty::is(atty::Stream::Stdout))
     }
 
+    /// Returns `true` if standard error should use color escapes.
+    /// Automatically checks if Zebra is running in a terminal.
+    pub fn use_color_stderr(&self) -> bool {
+        self.force_use_color || (self.use_color && atty::is(atty::Stream::Stderr))
+    }
+
     /// Returns `true` if output that could go to standard output or standard error
     /// should use color escapes. Automatically checks if Zebra is running in a terminal.
     pub fn use_color_stdout_and_stderr(&self) -> bool {

zebrad/src/components/tracing/component.rs

@@ -15,12 +15,26 @@ use tracing_subscriber::{
     util::SubscriberInitExt,
     EnvFilter,
 };
+use zebra_chain::parameters::Network;
 
 use crate::{application::build_version, components::tracing::Config};
 
 #[cfg(feature = "flamegraph")]
 use super::flame;
 
+// Art generated with these two images.
+// Zebra logo: book/theme/favicon.png
+// Heart image: https://commons.wikimedia.org/wiki/File:Heart_coraz%C3%B3n.svg
+// (License: CC BY-SA 3.0)
+//
+// How to render
+//
+// Convert heart image to PNG (2000px) and run:
+// img2txt -W 40 -H 20 -f utf8 -d none Heart_corazón.svg.png > heart.utf8
+// img2txt -W 40 -H 20 -f utf8 -d none favicon.png > logo.utf8
+// paste favicon.utf8 heart.utf8 > zebra.utf8
+static ZEBRA_ART: [u8; include_bytes!("zebra.utf8").len()] = *include_bytes!("zebra.utf8");
+
 /// A type-erased boxed writer that can be sent between threads safely.
 pub type BoxWrite = Box<dyn Write + Send + Sync + 'static>;
 
@@ -52,15 +66,36 @@ pub struct Tracing {
 
 impl Tracing {
     /// Try to create a new [`Tracing`] component with the given `filter`.
-    #[allow(clippy::print_stdout, clippy::print_stderr)]
-    pub fn new(config: Config) -> Result<Self, FrameworkError> {
+    #[allow(clippy::print_stdout, clippy::print_stderr, clippy::unwrap_in_result)]
+    pub fn new(network: Network, config: Config) -> Result<Self, FrameworkError> {
         // Only use color if tracing output is being sent to a terminal or if it was explicitly
         // forced to.
         let use_color = config.use_color_stdout();
+        let use_color_stderr = config.use_color_stderr();
 
         let filter = config.filter.unwrap_or_default();
         let flame_root = &config.flamegraph;
 
+        // If it's a terminal and color escaping is enabled: clear screen and
+        // print Zebra logo (here `use_color` is being interpreted as
+        // "use escape codes")
+        if use_color_stderr {
+            // Clear screen
+            eprint!("\x1B[2J");
+            eprintln!(
+                "{}",
+                std::str::from_utf8(&ZEBRA_ART)
+                    .expect("should always work on a UTF-8 encoded constant")
+            );
+        }
+
+        eprintln!(
+            "Thank you for running a {} zebrad {} node!",
+            network.lowercase_name(),
+            build_version()
+        );
+        eprintln!("You're helping to strengthen the network and contributing to a social good :)");
+
         let writer = if let Some(log_file) = config.log_file.as_ref() {
             println!("running zebra");
 
@@ -263,10 +298,6 @@ impl Tracing {
             howudoin::init(terminal_consumer);
 
             info!("activated progress bar");
-
-            if config.log_file.is_some() {
-                eprintln!("waiting for initial progress reports...");
-            }
         }
 
         Ok(Self {

zebrad/src/components/tracing/zebra.utf8

@@ -0,0 +1,20 @@
+              X@8:::::::@X              	                                        
+          @::X:;SX;%8S8@@:X::8          	                                        
+       @:;@8@.S8  ;;t;. XX.;@@;:@       	       8;     %X        X%     ;8       
+     8:@88     .%@.S@.XS:     888:8     	    X            ::  .:            X    
+    :;SX    XS8;::@X@8::;8t8:   8;;:@   	   %               SS               %   
+  @::@    88:::8 8::88::::::X@    8::8  	  S                                  X  
+ @:XS8   ;::::::8.88%8@S88::::8:  8S8:8 	  X                                  S  
+ ::;8 t8S8::::@St 88SX @SS@8:8S;8S @@:: 	  8                                  8  
+8:XX  %%@@::X% 8:  X@ t:8t X ..%t8  ;8:8	                                        
+::8t:  tX:X8tS 8: :@ ;.8@.X tt888:  @8::	   @                                X   
+::8S:  @:8Xtt% 8: S 8 8S.   .8;::.  88::	    8                              8    
+::X8   S@8   8:8.@8@8Xt S  .%8;S    %8::	      :                          :      
+ ::@8  S .   @:::::::X;@ 8.88S8    @8;:X	       ::                      :;       
+ 8:X8X .@:X88:::::::::888 @;:X    %88:: 	          t                  t          
+  @::S    888@8:::::::::8X; 8     8::8  	            8              8            
+   X:;S@   tXX8;::::::::S::@8   8;S:8   	              X.        .X              
+     ::8S@     :S88XX@8X:     @XX::     	                ::    ::                
+       8:;%X8.:S        t; X8%S:8X      	                   tt                   
+         X8::8SS8SX8@@X@8;8S:8X         	                                        
+              X@8:::::::@XS