From 8b7d1040b0d4c74adc4e5d9ff7443f7f64d2cf05 Mon Sep 17 00:00:00 2001
From: Bruno Paulino <bruno.paulino@n26.com>
Date: Tue, 2 Jan 2024 12:03:54 +0100
Subject: [PATCH] Write state to GHA state file

---
 .../src/{commands.rs => cli_commands.rs}      | 10 ++--
 decay_gha/src/gha_commands.rs                 | 27 +++++++++++
 decay_gha/src/main.rs                         | 46 +++++++++++++------
 3 files changed, 65 insertions(+), 18 deletions(-)
 rename decay_gha/src/{commands.rs => cli_commands.rs} (71%)
 create mode 100644 decay_gha/src/gha_commands.rs

diff --git a/decay_gha/src/commands.rs b/decay_gha/src/cli_commands.rs
similarity index 71%
rename from decay_gha/src/commands.rs
rename to decay_gha/src/cli_commands.rs
index b636ebe..bd5bf68 100644
--- a/decay_gha/src/commands.rs
+++ b/decay_gha/src/cli_commands.rs
@@ -11,7 +11,8 @@ pub struct Cli {
 
 #[derive(Debug, Subcommand)]
 pub enum Commands {
-    /// Starts the given Decay server
+    /// Starts the given Decay server and
+    /// store its pid on the Github state
     #[command(arg_required_else_help = true)]
     Start {
         /// Path to the Decay server binary
@@ -19,10 +20,13 @@ pub enum Commands {
         /// Port to bind the Decay server to during startup
         port: String,
     },
-    /// Stop a previusly started Decay server using this CLI
+    /// Stop a process with the given ID
     #[command(arg_required_else_help = true)]
-    Stop {
+    StopWithPid {
         /// The pid of the Decay server
         pid: String,
     },
+    /// Stop a previously running Decay server with
+    /// its pid stored on the Github Actions runner state
+    Stop,
 }
diff --git a/decay_gha/src/gha_commands.rs b/decay_gha/src/gha_commands.rs
new file mode 100644
index 0000000..72af0f2
--- /dev/null
+++ b/decay_gha/src/gha_commands.rs
@@ -0,0 +1,27 @@
+use std::{
+    env::{self},
+    fs::OpenOptions,
+};
+
+use std::io::prelude::*;
+
+pub fn save_state(key: &str, value: &str) {
+    let state = format!("{}={}", key, value);
+    let gha_file_path = env::var("GITHUB_STATE")
+        .unwrap_or_else(|_| panic!("Could not read GITHUB_STATE env variable"));
+    println!("GHA state file: {}", gha_file_path);
+
+    let mut gha_file = OpenOptions::new()
+        .write(true)
+        .append(true)
+        .open(gha_file_path)
+        .expect("GHA file should be available");
+
+    if let Err(e) = writeln!(gha_file, "{}", &state) {
+        panic!("Could not write to GHA state file: {}", e);
+    }
+}
+
+pub fn get_state(key: &str) -> Result<String, env::VarError> {
+    env::var(format!("STATE_{}", key))
+}
diff --git a/decay_gha/src/main.rs b/decay_gha/src/main.rs
index 1f27eaf..c60822c 100644
--- a/decay_gha/src/main.rs
+++ b/decay_gha/src/main.rs
@@ -1,5 +1,6 @@
 extern crate clap;
-mod commands;
+mod cli_commands;
+mod gha_commands;
 use std::io::{self, Write};
 
 use std::{
@@ -8,7 +9,12 @@ use std::{
 };
 
 use clap::Parser;
-use commands::{Cli, Commands};
+use cli_commands::{Cli, Commands};
+use gha_commands::get_state;
+
+use crate::gha_commands::save_state;
+
+const PID_STATE_KEY: &str = "decay-pid";
 
 fn main() {
     let args = Cli::parse();
@@ -26,6 +32,7 @@ fn main() {
             {
                 Ok(child_process) => {
                     println!("Starting up server with pid {}", child_process.id());
+                    save_state(PID_STATE_KEY, &child_process.id().to_string());
                     process::exit(0);
                 }
                 Err(err) => {
@@ -34,19 +41,28 @@ fn main() {
                 }
             }
         }
-        Commands::Stop { pid } => {
-            println!("Stopping process with pid: {}", pid);
-            let output = Command::new("kill")
-                .arg(&pid)
-                .output()
-                .unwrap_or_else(|_| panic!("Could not stop decay server with pid {}", &pid));
-            io::stdout().write_all(&output.stdout).unwrap();
-            io::stderr().write_all(&output.stderr).unwrap();
-            if output.status.success() {
-                process::exit(0);
-            } else {
-                process::exit(1);
-            }
+        Commands::StopWithPid { pid } => {
+            stop_process(&pid);
+        }
+        Commands::Stop => {
+            let pid = get_state(PID_STATE_KEY)
+                .unwrap_or_else(|_| panic!("pid could not be read from GHA state"));
+            stop_process(&pid);
         }
     }
 }
+
+fn stop_process(pid: &str) {
+    println!("Stopping process with pid: {}", pid);
+    let output = Command::new("kill")
+        .arg(pid)
+        .output()
+        .unwrap_or_else(|_| panic!("Could not stop decay server with pid {}", &pid));
+    io::stdout().write_all(&output.stdout).unwrap();
+    io::stderr().write_all(&output.stderr).unwrap();
+    if output.status.success() {
+        process::exit(0);
+    } else {
+        process::exit(1);
+    }
+}