tools/unitctl: unitctl export

* new subcommand for "export" in CLI
* new cmd submodule for exporting config tarballs
* logic to also output to stdout
* README additions
* limitations documented

Signed-off-by: Ava Hahn <a.hahn@f5.com>

tools/unitctl/README.md

@@ -157,6 +157,20 @@ Imported /opt/unit/config/put.json -> /config
 Imported 3 files
 ```
 
+### Export configuration from a running Unit instance
+```
+$ unitctl export -f config.tar
+```
+
+Addtionally, standard out can be used:
+```
+$ unitctl export -f -
+$ unitctl export -f - | tar xf - config.json
+$ unitctl export -f - > config.tar
+```
+
+*Note:* The exported configuration will be devoid of any installed certificates. The Unit configuration API does not support fetching certificates or private keys once installed. User's will need to add relevant certificates and keys to an export.
+
 ### Wait for socket to become available
 ```
 $ unitctl --wait-timeout-seconds=3 --wait-max-tries=4 import /opt/unit/config`

tools/unitctl/unitctl/Cargo.toml

@@ -32,6 +32,7 @@ hyperlocal = "0.8"
 hyper-tls = "0.5"
 tokio = { version = "1.35", features = ["macros"] }
 futures = "0.3"
+tar = "0.4.41"
 
 [package.metadata.deb]
 copyright = "2022, F5"

tools/unitctl/unitctl/src/cmd/mod.rs

@@ -4,3 +4,4 @@ pub(crate) mod import;
 pub(crate) mod instances;
 pub(crate) mod listeners;
 pub(crate) mod status;
+pub(crate) mod save;

tools/unitctl/unitctl/src/cmd/save.rs

@@ -0,0 +1,52 @@
+use crate::unitctl::UnitCtl;
+use crate::wait;
+use crate::UnitctlError;
+use crate::requests::send_empty_body_deserialize_response;
+use unit_client_rs::unit_client::UnitClient;
+use tar::{Builder, Header};
+use std::fs::File;
+use std::io::stdout;
+
+
+pub async fn cmd(
+    cli: &UnitCtl,
+    filename: &String
+) -> Result<(), UnitctlError> {
+    if !filename.ends_with(".tar") {
+        eprintln!("Warning: writing uncompressed tarball to {}", filename);
+    }
+
+    let control_socket = wait::wait_for_socket(cli).await?;
+    let client = UnitClient::new(control_socket);
+
+    let config_res = serde_json::to_string_pretty(
+        &send_empty_body_deserialize_response(&client, "GET", "/config").await?
+    );
+    if let Err(e) = config_res {
+        return Err(UnitctlError::DeserializationError{message: e.to_string()})
+    }
+
+    let current_config = config_res
+        .unwrap()
+        .into_bytes();
+
+    //let current_js_modules = send_empty_body_deserialize_response(&client, "GET", "/js_modules")
+    //    .await?;
+
+    let mut conf_header = Header::new_gnu();
+    conf_header.set_size(current_config.len() as u64);
+    conf_header.set_mode(0o644);
+    conf_header.set_cksum();
+
+    // builder has a different type depending on output
+    if filename == "-" {
+        let mut ar = Builder::new(stdout());
+        ar.append_data(&mut conf_header, "config.json", current_config.as_slice()).unwrap();
+    } else {
+        let file = File::create(filename).unwrap();
+        let mut ar = Builder::new(file);
+        ar.append_data(&mut conf_header, "config.json", current_config.as_slice()).unwrap();
+    }
+
+    Ok(())
+}

tools/unitctl/unitctl/src/main.rs

@@ -8,7 +8,7 @@ extern crate unit_client_rs;
 
 use clap::Parser;
 
-use crate::cmd::{edit, execute as execute_cmd, import, instances, listeners, status};
+use crate::cmd::{edit, execute as execute_cmd, import, instances, listeners, status, save};
 use crate::output_format::OutputFormat;
 use crate::unitctl::{Commands, UnitCtl};
 use crate::unitctl_error::UnitctlError;
@@ -44,6 +44,8 @@ async fn main() -> Result<(), UnitctlError> {
         Commands::Status { output_format } => status::cmd(&cli, output_format).await,
 
         Commands::Listeners { output_format } => listeners::cmd(&cli, output_format).await,
+
+        Commands::Export { ref filename } => save::cmd(&cli, filename).await,
     }
     .map_err(|error| {
         eprint_error(&error);

tools/unitctl/unitctl/src/unitctl.rs

@@ -114,6 +114,15 @@ pub(crate) enum Commands {
         )]
         output_format: OutputFormat,
     },
+    #[command(about = "Export the current configuration of UNIT")]
+    Export {
+        #[arg(
+            required = true,
+            short = 'f',
+            help = "tarball filename to save configuration to"
+        )]
+        filename: String
+    },
 }
 
 #[derive(Debug, Args)]