Implementation:Ollama Ollama Modelfile Format Spec

Knowledge Sources	Ollama Modelfile Docs
Domains	Configuration, DSL
Last Updated	2026-02-14 00:00 GMT

Overview

Pattern specification for the Modelfile configuration language used to define custom models in Ollama.

Description

This is a Pattern Doc — it documents a user-authored format rather than a library API. The Modelfile is a text file containing directives that configure a custom model. The format is parsed by the parser package.

The Modelfile struct in the parser package holds the parsed commands. The Command struct represents each directive with Name and Args fields.

Usage

Users author Modelfiles when creating custom models via ollama create. The file is read and parsed by ParseFile before being processed by the creation pipeline.

Code Reference

Source Location

• Repository: ollama
• File: parser/parser.go
• Lines: L30-55 (Modelfile struct), L326-369 (Command struct)

Interface Specification

# Modelfile Format Specification

# Required: base model
FROM <model_name_or_gguf_path>

# Optional: system prompt (multiline with triple quotes)
SYSTEM """
You are a helpful assistant.
"""

# Optional: inference parameters
PARAMETER temperature 0.7
PARAMETER top_k 40
PARAMETER top_p 0.9
PARAMETER num_ctx 4096
PARAMETER stop "<|end|>"

# Optional: chat template override (Go text/template)
TEMPLATE """
{{- range .Messages }}
<|{{ .Role }}|>
{{ .Content }}
{{- end }}
"""

# Optional: LoRA adapter
ADAPTER /path/to/adapter.gguf

# Optional: license
LICENSE """
MIT License...
"""

# Optional: preset messages
MESSAGE user "Hello"
MESSAGE assistant "Hi! How can I help?"

I/O Contract

Inputs

Name	Type	Required	Description
FROM	string	Yes	Base model name or path to GGUF file
SYSTEM	string	No	System prompt text
PARAMETER	key-value	No	Inference parameter (temperature, top_k, etc.)
TEMPLATE	string	No	Go text/template for prompt formatting
ADAPTER	string	No	Path to LoRA adapter file
LICENSE	string	No	Model license text
MESSAGE	role + content	No	Preset conversation message

Outputs

Name	Type	Description
Modelfile	Parsed struct	Modelfile struct with Commands slice
CreateRequest	api.CreateRequest	Translated API request for model creation

Usage Examples

Basic Custom Model

# Create a Modelfile
cat > Modelfile << 'EOF'
FROM llama3
SYSTEM "You are Mario from Super Mario Bros."
PARAMETER temperature 0.8
EOF

# Create the model
ollama create mario -f Modelfile

# Run it
ollama run mario

Model with LoRA Adapter

cat > Modelfile << 'EOF'
FROM llama3
ADAPTER ./my-lora-adapter
PARAMETER num_ctx 8192
EOF

ollama create custom-llama -f Modelfile

Related Pages

Implements Principle

• Principle:Ollama_Ollama_Modelfile_Format