🐳 build: add Tini to Docker image, simplify Git version injection

Building the Git version into the code meant that Cargo had to recompile
ptth_relay every time I built. This is annoying and it doesn't add anything.

I changed it to read the Git version from a text file which is absent by
default, and present in the Docker image.

Dockerfile

@@ -53,9 +53,6 @@ COPY ./handlebars/ ./handlebars
 # Docker doing something funny with mtimes? Maybe?
 RUN touch crates/ptth_core/src/lib.rs
 
-ARG git_version
-RUN echo -n "$git_version" > crates/ptth_relay/src/git_version.txt
-
 # build for release
 # gate only on ptth_relay tests for now
 RUN \
@@ -66,12 +63,15 @@ cargo test --release -p ptth_relay
 FROM debian@sha256:240f770008bdc538fecc8d3fa7a32a533eac55c14cbc56a9a8a6f7d741b47e33
 
 RUN apt-get update \
-&& apt-get install -y libssl1.1 ca-certificates \
-&& apt-get upgrade -y
+&& apt-get upgrade -y \
+&& apt-get install -y libssl1.1 ca-certificates tini \
+&& mkdir -p /root
 
 COPY --from=build /ptth/target/release/ptth_relay             /root/
-COPY --from=build /ptth/crates/ptth_relay/src/git_version.txt /root/
 COPY --from=build /ptth/handlebars                            /root/handlebars
 
+ARG git_version
+RUN echo -n "$git_version" > /root/git_version.txt
+
 WORKDIR /root
-ENTRYPOINT ["./ptth_relay"]
+ENTRYPOINT ["/usr/bin/tini", "--", "./ptth_relay"]

crates/ptth_relay/src/git_version.rs

@@ -1 +1,14 @@
-pub const GIT_VERSION: &str = include_str! ("git_version.txt");
+pub fn read_git_version () -> Option <String> {
+	use std::{
+		io::Read,
+		fs::File,
+	};
+	
+	let mut buf = vec! [0u8; 512];
+	
+	let mut f = File::open ("git_version.txt").ok ()?;
+	let bytes_read = f.read (&mut buf).ok ()?;
+	buf.truncate (bytes_read);
+	
+	Some (String::from_utf8 (buf).ok ()?)
+}

crates/ptth_relay/src/git_version.txt

@@ -1 +0,0 @@
-(Unknown)

crates/ptth_relay/src/main.rs

@@ -16,7 +16,7 @@ use tracing_subscriber::{
 
 use ptth_relay::{
 	Config,
-	git_version::GIT_VERSION,
+	git_version::read_git_version,
 	RelayState,
 	run_relay,
 };
@@ -32,7 +32,10 @@ async fn main () -> Result <(), Box <dyn Error>> {
 	let config_path = PathBuf::from ("config/ptth_relay.toml");
 	let config = Config::from_file (&config_path).await?;
 	
-	info! ("ptth_relay Git version: {:?}", GIT_VERSION);
+	match read_git_version () {
+		Some (x) => info! ("ptth_relay Git version: {:?}", x),
+		None => info! ("ptth_relay not built from Git"),
+	}
 	
 	let (shutdown_rx, forced_shutdown) = ptth_core::graceful_shutdown::init_with_force ();
 	

todo.md

@@ -1,7 +1,7 @@
 Interesting issues will get a unique ID with
 `dd if=/dev/urandom bs=5 count=1 | base32`
 
-- Diagram dependencies
+- Move Git version out of source code and into a plain file in the Docker image
 - Report server version in HTML
 - Apply https://github.com/hexops/dockerfile to Dockerfile
 - [YNQAQKJS](issues/2020-12Dec/auth-route-YNQAQKJS.md) Open new auth route for spiders / scrapers