Create convert_diffusers_sdxl_lora_to_webui.py (#6395)

* Create convert_diffusers_sdxl_lora_to_webui.py

* Move some conversion logic to utils

* fix logging import

* Add usage example

---------
Co-authored-by: multimodalart <joaopaulo.passos+multimodal@gmail.com>

scripts/convert_diffusers_sdxl_lora_to_webui.py

+# Script for converting a Hugging Face Diffusers trained SDXL LoRAs to Kohya format
+# This means that you can input your diffusers-trained LoRAs and
+# Get the output to work with WebUIs such as AUTOMATIC1111, ComfyUI, SD.Next and others.
+
+# To get started you can find some cool `diffusers` trained LoRAs such as this cute Corgy
+# https://huggingface.co/ignasbud/corgy_dog_LoRA/, download its `pytorch_lora_weights.safetensors` file
+# and run the script:
+# python convert_diffusers_sdxl_lora_to_webui.py --input_lora pytorch_lora_weights.safetensors --output_lora corgy.safetensors
+# now you can use corgy.safetensors in your WebUI of choice!
+
+# To train your own, here are some diffusers training scripts and utils that you can use and then convert:
+# LoRA Ease - no code SDXL Dreambooth LoRA trainer: https://huggingface.co/spaces/multimodalart/lora-ease
+# Dreambooth Advanced Training Script - state of the art techniques such as pivotal tuning and prodigy optimizer:
+# - Script: https://github.com/huggingface/diffusers/blob/main/examples/advanced_diffusion_training/train_dreambooth_lora_sdxl_advanced.py
+# - Colab (only on Pro): https://colab.research.google.com/github/huggingface/notebooks/blob/main/diffusers/SDXL_Dreambooth_LoRA_advanced_example.ipynb
+# Canonical diffusers training scripts:
+# - Script: https://github.com/huggingface/diffusers/blob/main/examples/dreambooth/train_dreambooth_lora_sdxl.py
+# - Colab (runs on free tier): https://colab.research.google.com/github/huggingface/notebooks/blob/main/diffusers/SDXL_DreamBooth_LoRA_.ipynb
+
+import argparse
+import os
+
+from safetensors.torch import load_file, save_file
+
+from diffusers.utils import convert_all_state_dict_to_peft, convert_state_dict_to_kohya
+
+
+def convert_and_save(input_lora, output_lora=None):
+    if output_lora is None:
+        base_name = os.path.splitext(input_lora)[0]
+        output_lora = f"{base_name}_webui.safetensors"
+
+    diffusers_state_dict = load_file(input_lora)
+    peft_state_dict = convert_all_state_dict_to_peft(diffusers_state_dict)
+    kohya_state_dict = convert_state_dict_to_kohya(peft_state_dict)
+    save_file(kohya_state_dict, output_lora)
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="Convert LoRA model to PEFT and then to Kohya format.")
+    parser.add_argument(
+        "input_lora",
+        type=str,
+        help="Path to the input LoRA model file in the diffusers format.",
+    )
+    parser.add_argument(
+        "output_lora",
+        type=str,
+        nargs="?",
+        help="Path for the converted LoRA (safetensors format for AUTOMATIC1111, ComfyUI, etc.). Optional, defaults to input name with a _webui suffix.",
+    )
+
+    args = parser.parse_args()
+
+    convert_and_save(args.input_lora, args.output_lora)

src/diffusers/utils/state_dict_utils.py

@@ -16,6 +16,11 @@ State dict utilities: utility methods for converting state dicts easily
 """
 import enum
 
+from .logging import get_logger
+
+
+logger = get_logger(__name__)
+
 
 class StateDictType(enum.Enum):
     """
@@ -23,7 +28,7 @@ class StateDictType(enum.Enum):
     """
 
     DIFFUSERS_OLD = "diffusers_old"
-    # KOHYA_SS = "kohya_ss" # TODO: implement this
+    KOHYA_SS = "kohya_ss"
     PEFT = "peft"
     DIFFUSERS = "diffusers"
 
@@ -100,6 +105,14 @@ DIFFUSERS_OLD_TO_DIFFUSERS = {
     ".to_out_lora.down": ".out_proj.lora_linear_layer.down",
 }
 
+PEFT_TO_KOHYA_SS = {
+    "lora_A": "lora_down",
+    "lora_B": "lora_up",
+    # This is not a comprehensive dict as kohya format requires replacing `.` with `_` in keys,
+    # adding prefixes and adding alpha values
+    # Check `convert_state_dict_to_kohya` for more
+}
+
 PEFT_STATE_DICT_MAPPINGS = {
     StateDictType.DIFFUSERS_OLD: DIFFUSERS_OLD_TO_PEFT,
     StateDictType.DIFFUSERS: DIFFUSERS_TO_PEFT,
@@ -110,6 +123,8 @@ DIFFUSERS_STATE_DICT_MAPPINGS = {
     StateDictType.PEFT: PEFT_TO_DIFFUSERS,
 }
 
+KOHYA_STATE_DICT_MAPPINGS = {StateDictType.PEFT: PEFT_TO_KOHYA_SS}
+
 KEYS_TO_ALWAYS_REPLACE = {
     ".processor.": ".",
 }
@@ -228,3 +243,82 @@ def convert_unet_state_dict_to_peft(state_dict):
     """
     mapping = UNET_TO_DIFFUSERS
     return convert_state_dict(state_dict, mapping)
+
+
+def convert_all_state_dict_to_peft(state_dict):
+    r"""
+    Attempts to first `convert_state_dict_to_peft`, and if it doesn't detect `lora_linear_layer`
+    for a valid `DIFFUSERS` LoRA for example, attempts to exclusively convert the Unet `convert_unet_state_dict_to_peft`
+    """
+    try:
+        peft_dict = convert_state_dict_to_peft(state_dict)
+    except Exception as e:
+        if str(e) == "Could not automatically infer state dict type":
+            peft_dict = convert_unet_state_dict_to_peft(state_dict)
+        else:
+            raise
+
+    if not any("lora_A" in key or "lora_B" in key for key in peft_dict.keys()):
+        raise ValueError("Your LoRA was not converted to PEFT")
+
+    return peft_dict
+
+
+def convert_state_dict_to_kohya(state_dict, original_type=None, **kwargs):
+    r"""
+    Converts a `PEFT` state dict to `Kohya` format that can be used in AUTOMATIC1111, ComfyUI, SD.Next, InvokeAI, etc.
+    The method only supports the conversion from PEFT to Kohya for now.
+
+    Args:
+        state_dict (`dict[str, torch.Tensor]`):
+            The state dict to convert.
+        original_type (`StateDictType`, *optional*):
+            The original type of the state dict, if not provided, the method will try to infer it automatically.
+        kwargs (`dict`, *args*):
+            Additional arguments to pass to the method.
+
+            - **adapter_name**: For example, in case of PEFT, some keys will be pre-pended
+                with the adapter name, therefore needs a special handling. By default PEFT also takes care of that in
+                `get_peft_model_state_dict` method:
+                https://github.com/huggingface/peft/blob/ba0477f2985b1ba311b83459d29895c809404e99/src/peft/utils/save_and_load.py#L92
+                but we add it here in case we don't want to rely on that method.
+    """
+    try:
+        import torch
+    except ImportError:
+        logger.error("Converting PEFT state dicts to Kohya requires torch to be installed.")
+        raise
+
+    peft_adapter_name = kwargs.pop("adapter_name", None)
+    if peft_adapter_name is not None:
+        peft_adapter_name = "." + peft_adapter_name
+    else:
+        peft_adapter_name = ""
+
+    if original_type is None:
+        if any(f".lora_A{peft_adapter_name}.weight" in k for k in state_dict.keys()):
+            original_type = StateDictType.PEFT
+
+    if original_type not in KOHYA_STATE_DICT_MAPPINGS.keys():
+        raise ValueError(f"Original type {original_type} is not supported")
+
+    # Use the convert_state_dict function with the appropriate mapping
+    kohya_ss_partial_state_dict = convert_state_dict(state_dict, KOHYA_STATE_DICT_MAPPINGS[StateDictType.PEFT])
+    kohya_ss_state_dict = {}
+
+    # Additional logic for replacing header, alpha parameters `.` with `_` in all keys
+    for kohya_key, weight in kohya_ss_partial_state_dict.items():
+        if "text_encoder_2." in kohya_key:
+            kohya_key = kohya_key.replace("text_encoder_2.", "lora_te2.")
+        elif "text_encoder." in kohya_key:
+            kohya_key = kohya_key.replace("text_encoder.", "lora_te1.")
+        elif "unet" in kohya_key:
+            kohya_key = kohya_key.replace("unet", "lora_unet")
+        kohya_key = kohya_key.replace(".", "_", kohya_key.count(".") - 2)
+        kohya_key = kohya_key.replace(peft_adapter_name, "")  # Kohya doesn't take names
+        kohya_ss_state_dict[kohya_key] = weight
+        if "lora_down" in kohya_key:
+            alpha_key = f'{kohya_key.split(".")[0]}.alpha'
+            kohya_ss_state_dict[alpha_key] = torch.tensor(len(weight))
+
+    return kohya_ss_state_dict