improve development server handling

hyperglass/util.py

@@ -11,6 +11,9 @@ def _logger():
     return _loguru_logger
 
 
+log = _logger()
+
+
 def cpu_count():
     """Get server's CPU core count.
 
@@ -42,4 +45,66 @@ def check_python():
     return pretty_version
 
 
-log = _logger()
+async def build_ui():
+    """Execute `yarn build` from UI directory.
+
+    Raises:
+        RuntimeError: Raised if exit code is not 0.
+        RuntimeError: Raised when any other error occurs.
+    """
+    import asyncio
+    from pathlib import Path
+    import ujson as json
+
+    ui_dir = Path(__file__).parent.parent / "ui"
+
+    yarn_command = "yarn --silent --emoji false --json --no-progress build"
+    try:
+        proc = await asyncio.create_subprocess_shell(
+            cmd=yarn_command,
+            stdout=asyncio.subprocess.PIPE,
+            stderr=asyncio.subprocess.PIPE,
+            cwd=ui_dir,
+        )
+
+        stdout, stderr = await asyncio.wait_for(proc.communicate(), timeout=60)
+        output_out = json.loads(stdout.decode("utf-8").split("\n")[0])
+
+        if proc.returncode != 0:
+            output_error = json.loads(stderr.decode("utf-8").strip("\n"))
+            raise RuntimeError(
+                f'Error building web assets with script {output_out["data"]}:'
+                f'{output_error["data"]}'
+            )
+
+        await proc.wait()
+    except Exception as e:
+        raise RuntimeError(str(e))
+
+    return output_out["data"]
+
+
+async def write_env(vars):
+    """Write environment variables to temporary JSON file.
+
+    Arguments:
+        vars {dict} -- Environment variables to write.
+
+    Raises:
+        RuntimeError: Raised on any errors.
+    """
+    from aiofile import AIOFile
+    import ujson as json
+    from pathlib import Path
+
+    env_file = Path("/tmp/hyperglass.env.json")
+    env_vars = json.dumps(vars)
+
+    try:
+        async with AIOFile(env_file, "w+") as ef:
+            await ef.write(env_vars)
+            await ef.fsync()
+    except Exception as e:
+        raise RuntimeError(str(e))
+
+    return True