Fine-tune Llama 3.1 with LoRA using Soup CLI
This guide shows how to fine-tune Meta Llama 3.1 8B with LoRA adapters on a custom dataset using Soup CLI. End-to-end from install to inference in under 10 minutes on a single GPU.
Why LoRA on Llama 3.1?
LoRA (Low-Rank Adaptation) trains only a small fraction (~0.1%) of model parameters, which means:
- Train 8B parameter Llama 3.1 on a single 24GB GPU (RTX 4090, A10)
- Checkpoints are tiny (~100MB instead of 16GB)
- Faster training and easier experimentation
1. Install
pip install "soup-cli[train,fast]"Since v0.71.0 the base
soup-clipackage is a light, PyTorch-free CLI.[train]adds the training stack;[fast]adds Unsloth on top. Installing[fast]alone cannot train.
The [fast] extra adds Unsloth for 2–5× training speedup on Llama-family models.
2. Prepare your dataset
Use the Alpaca format (JSON list of instruction/input/output triples):
[
{
"instruction": "Summarize the following text.",
"input": "Soup CLI is a fine-tuning toolkit...",
"output": "Soup CLI is an open-source LLM fine-tuning tool."
}
]Save as train.json.
3. Create the config
Save as llama31.yaml:
base: meta-llama/Llama-3.1-8B-Instruct
task: sft
backend: unsloth # root-level, NOT under training
data:
train: train.json
format: alpaca
max_length: 2048 # sequence length lives under data
training:
epochs: 3
lr: 2.0e-4 # the key is lr, not learning_rate
batch_size: 2
gradient_accumulation_steps: 8
lora:
r: 16 # LoRA turns on when r > 0; there is no enabled flag
alpha: 32
dropout: 0.05
target_modules: [q_proj, k_proj, v_proj, o_proj]
output: ./runs/llama31Config keys are validated, but unknown keys are ignored rather than rejected. Writing
learning_rateinstead oflr, or nestingbackendundertraining, does not raise: the value is silently dropped and the default is used instead. If a setting seems to have no effect, check the spelling against Configuration first.
4. Train
soup train --config llama31.yamlSoup auto-detects GPU, enables FlashAttention, and trains LoRA adapters. Expect ~20 minutes for 1k examples on an RTX 4090.
5. Chat with your fine-tuned model
soup chat --model ./runs/llama31/latest6. Export for deployment
# Merge LoRA into base model and export GGUF for Ollama
soup export --model ./runs/llama31/latest --format gguf --quant q4_k_mTroubleshooting
Out of memory? Enable QLoRA (a 4-bit base model). Note 4bit is already the default, so this is only worth setting explicitly if you changed it:
training:
quantization: 4bit
lora:
r: 16Slow training? Ensure backend: unsloth is set at the root of the config (not under training) and that you installed pip install "soup-cli[train,fast]".
Next steps
Soup is free and Apache-2.0. If it saved you a training run, starring the repo costs nothing and helps most. You can also fund the GPU time behind the work a 4 GB laptop cannot reach.