shim: pass environment variables to spawned process

Enhanace spawn() to pass envrionment variables to child process.

Signed-off-by: Liu Jiang <gerry@linux.alibaba.com>

crates/shim/examples/empty_shim.rs

@@ -37,7 +37,7 @@ impl shim::Shim for Service {
     }
 
     fn start_shim(&mut self, opts: shim::StartOpts) -> Result<String, shim::Error> {
-        let address = shim::spawn(opts)?;
+        let address = shim::spawn(opts, Vec::new())?;
         Ok(address)
     }
 }

crates/shim/src/lib.rs

@@ -316,7 +316,7 @@ fn start_listener(address: &str) -> Result<UnixListener, Error> {
 
 /// Spawn is a helper func to launch shim process.
 /// Typically this expected to be called from `StartShim`.
-pub fn spawn(opts: StartOpts) -> Result<String, Error> {
+pub fn spawn(opts: StartOpts, vars: Vec<(&str, &str)>) -> Result<String, Error> {
     let cmd = env::current_exe()?;
     let cwd = env::current_dir()?;
     let address = socket_address(&opts.address, &opts.namespace, &opts.id);
@@ -342,7 +342,8 @@ pub fn spawn(opts: StartOpts) -> Result<String, Error> {
             &opts.id,
             "-address",
             &opts.address,
-        ]);
+        ])
+        .envs(vars);
 
     command.spawn().map_err(Into::into).map(|_| {
         // Ownership of `listener` has been passed to child.