Adds chat templates (#1022)

README.md

@@ -589,6 +589,9 @@ datasets:
       # For `completion` datsets only, uses the provided field instead of `text` column
       field:
 
+# Saves the desired chat template to the tokenizer_config.json for easier inferencing
+# Currently supports chatml and inst (mistral/mixtral)
+chat_template: chatml
 # Axolotl attempts to save the dataset as an arrow after packing the data together so
 # subsequent training attempts load faster, relative path
 dataset_prepared_path: data/last_run_prepared

src/axolotl/utils/chat_templates.py

@@ -0,0 +1,29 @@
+"""
+This module provides functionality for selecting chat templates based on user choices.
+These templates are used for formatting messages in a conversation.
+"""
+
+
+def chat_templates(user_choice: str):
+    """
+    Finds the correct chat_template for the tokenizer_config.
+
+    Args:
+        user_choice (str): The user's choice of template.
+
+    Returns:
+        str: The chosen template string.
+
+    Raises:
+        ValueError: If the user_choice is not found in the templates.
+    """
+
+    templates = {
+        "inst": "{{ bos_token }}{% for message in messages %}{% if (message['role'] == 'user') != (loop.index0 % 2 == 0) %}{{ raise_exception('Conversation roles must alternate user/assistant/user/assistant/...') }}{% endif %}{% if message['role'] == 'user' %}{{ '[INST] ' + message['content'] + ' [/INST]' }}{% elif message['role'] == 'assistant' %}{{ message['content'] + eos_token}}{% else %}{{ raise_exception('Only user and assistant roles are supported!') }}{% endif %}{% endfor %}",  # I don't know what this one is called. Used by Mistral/Mixtral.
+        "chatml": "{% if not add_generation_prompt is defined %}{% set add_generation_prompt = false %}{% endif %}{% for message in messages %}{{'<|im_start|>' + message['role'] + '\n' + message['content'] + '<|im_end|>' + '\n'}}{% endfor %}{% if add_generation_prompt %}{{ '<|im_start|>assistant\n' }}{% endif %}",
+    }
+
+    if user_choice in templates:
+        return templates[user_choice]
+
+    raise ValueError(f"Template '{user_choice}' not found.")

src/axolotl/utils/models.py

@@ -26,6 +26,7 @@
 from axolotl.models.mamba import fix_mamba_attn_for_loss
 from axolotl.prompt_tokenizers import LLAMA_DEFAULT_EOS_TOKEN
 from axolotl.utils.bench import log_gpu_memory_usage
+from axolotl.utils.chat_templates import chat_templates
 from axolotl.utils.dict import DictDefault
 
 LOG = logging.getLogger("axolotl")
@@ -186,6 +187,12 @@ def load_tokenizer(cfg):
     LOG.debug(f"PAD: {tokenizer.pad_token_id} / {tokenizer.pad_token}")
     LOG.debug(f"UNK: {tokenizer.unk_token_id} / {tokenizer.unk_token}")
 
+    if cfg.chat_template:
+        tokenizer.chat_template = chat_templates(cfg.chat_template)
+    else:
+        LOG.info(
+            "No Chat template selected. Consider adding a chat template for easier inference."
+        )
     return tokenizer