CI (2592): Allow LoRA adapter revision in server launcher (#2602)

allow revision for lora adapters from launcher

Co-authored-by: Sida <sida@kulamind.com>
Co-authored-by: teamclouday <teamclouday@gmail.com>

Cargo.lock

@@ -4247,6 +4247,7 @@ dependencies = [
  "nix 0.28.0",
  "once_cell",
  "pyo3",
+ "regex",
  "reqwest",
  "serde",
  "serde_json",

docs/source/conceptual/lora.md

@@ -36,6 +36,12 @@ To use LoRA in TGI, when starting the server, you can specify the list of LoRA m
 LORA_ADAPTERS=predibase/customer_support,predibase/dbpedia
 ```
 
+To specify model revision, use `adapter_id@revision`, as follows:
+
+```bash
+LORA_ADAPTERS=predibase/customer_support@main,predibase/dbpedia@rev2
+```
+
 To use a locally stored lora adapter, use `adapter-name=/path/to/adapter`, as seen below. When you want to use this adapter, set `"parameters": {"adapter_id": "adapter-name"}"`
 
 ```bash

launcher/Cargo.toml

@@ -18,6 +18,7 @@ serde_json = "1.0.107"
 thiserror = "1.0.59"
 tracing = "0.1.37"
 tracing-subscriber = { version = "0.3.17", features = ["json", "env-filter"] }
+regex = "1.11.0"
 
 [dev-dependencies]
 float_eq = "1.0.1"

launcher/src/main.rs

@@ -5,6 +5,7 @@ use hf_hub::{
 };
 use nix::sys::signal::{self, Signal};
 use nix::unistd::Pid;
+use regex::Regex;
 use serde::Deserialize;
 use std::env;
 use std::ffi::OsString;
@@ -1808,14 +1809,37 @@ fn main() -> Result<(), LauncherError> {
             if adapter.contains('=') {
                 continue;
             }
+
+            let adapter = adapter.trim();
+
+            // check if adapter has more than 1 '@'
+            if adapter.matches('@').count() > 1 {
+                return Err(LauncherError::ArgumentValidation(format!(
+                    "Invalid LoRA adapter format: {}",
+                    adapter
+                )));
+            }
+
+            // capture adapter_id, path, revision in format of adapter_id=path@revision
+            let re = Regex::new(r"^([^=@]+)(?:=([^@]+))?(?:@(.+))?$").unwrap();
+            if let Some(caps) = re.captures(adapter) {
+                let adapter_id = caps.get(1).map_or("", |m| m.as_str());
+                let revision = caps.get(3).map(|m| m.as_str());
+
                 download_convert_model(
-                adapter,
-                None,
+                    adapter_id,
+                    revision,
                     args.trust_remote_code,
                     args.huggingface_hub_cache.as_deref(),
                     args.weights_cache_override.as_deref(),
                     running.clone(),
                 )?;
+            } else {
+                return Err(LauncherError::ArgumentValidation(format!(
+                    "Invalid LoRA adapter format: {}",
+                    adapter
+                )));
+            }
         }
     }