Version Detection

migetpacks automatically detects the language version for your project by checking environment variables, version files, and project configuration files in a defined priority order. If no version is found, a sensible default is used.

Detection Priority by Language

Each language checks sources in the order listed below. The first match wins.

Node.js

Priority	Source	Example
1	`NODE_VERSION` env var	`NODE_VERSION=20.11.0`
2	`.node-version` file	`20.11.0`
3	`.nvmrc` file	`20`
4	`package.json` `engines.node`	`"node": ">=20"`
-	Default	`22.16.0`

Bun

Priority	Source	Example
1	`BUN_VERSION` env var	`BUN_VERSION=1.1.0`
2	`.bun-version` file	`1.1.0`
3	`bunfig.toml` `version` field	`version = "1.1.0"`
-	Default	`1.3.4`

Deno

Priority	Source	Example
1	`DENO_VERSION` env var	`DENO_VERSION=2.0.0`
2	`.deno-version` file	`2.0.0`
3	`.dvmrc` file	`2.0.0`
4	`deno.json` `version` field	`"version": "2.0.0"`
-	Default	`2.6.1`

Ruby

Priority	Source	Example
1	`RUBY_VERSION` env var	`RUBY_VERSION=3.3.0`
2	`.ruby-version` file	`3.3.0`
3	`Gemfile` ruby directive	`ruby "3.3.0"`
-	Default	`3.4.4`

Python

Priority	Source	Example
1	`PYTHON_VERSION` env var	`PYTHON_VERSION=3.12.0`
2	`.python-version` file	`3.12.0`
3	`runtime.txt`	`python-3.12.0`
4	`uv.lock` `requires-python`	`requires-python = ">=3.13"`
5	`pyproject.toml` `requires-python`	`requires-python = ">=3.12"`
-	Default	`3.12.8`

Go

Priority	Source	Example
1	`GO_VERSION` env var	`GO_VERSION=1.22.0`
2	`.go-version` file	`1.22.0`
3	`go.mod` go directive	`go 1.22`
-	Default	`1.25.0`

Rust

Priority	Source	Example
1	`RUSTUP_TOOLCHAIN` env var	`RUSTUP_TOOLCHAIN=1.80.0`
2	`rust-toolchain` file	`1.80.0`
3	`rust-toolchain.toml` channel	`channel = "1.80.0"`
-	Default	`1.92.0`

PHP

Priority	Source	Example
1	`PHP_VERSION` env var	`PHP_VERSION=8.3`
2	`.php-version` file	`8.3`
3	`composer.json` `require.php`	`"php": ">=8.2"`
-	Default	`8.3`

Java

Priority	Source	Example
1	`JAVA_VERSION` env var	`JAVA_VERSION=21`
2	`.java-version` file	`21`
3	`system.properties`	`java.runtime.version=21`
4	`pom.xml` properties	`<java.version>21</java.version>`
-	Default	`21`

Kotlin

Priority	Source	Example
1	`KOTLIN_VERSION` env var	`KOTLIN_VERSION=2.0.0`
2	`.kotlin-version` file	`2.0.0`
3	`gradle.properties`	`kotlin.version=2.0.0`
4	`build.gradle.kts` plugin version	`kotlin("jvm") version "2.0.0"`
-	Default	`2.1.0`

Scala

Priority	Source	Example
1	`SCALA_VERSION` env var	`SCALA_VERSION=3.4.0`
2	`.scala-version` file	`3.4.0`
3	`build.sbt` scalaVersion	`scalaVersion := "3.4.0"`
4	`project/build.properties`	`scala.version=3.4.0`
-	Default	`3.5.2`

Clojure

Priority	Source	Example
1	`CLOJURE_VERSION` env var	`CLOJURE_VERSION=1.12.0`
2	`.clojure-version` file	`1.12.0`
3	`project.clj` dependency	`[org.clojure/clojure "1.12.0"]`
4	`deps.edn` dependency	`org.clojure/clojure {:mvn/version "1.12.0"}`
-	Default	`1.11.1`

.NET

Priority	Source	Example
1	`DOTNET_VERSION` env var	`DOTNET_VERSION=8.0`
2	`global.json` SDK version	`"version": "8.0.100"`
3	`*.csproj` TargetFramework	`<TargetFramework>net8.0</TargetFramework>`
-	Default	`8.0`

Elixir

Priority	Source	Example
1	`ELIXIR_VERSION` env var	`ELIXIR_VERSION=1.17.0`
2	`.elixir-version` file	`1.17.0`
3	`.tool-versions` (asdf)	`elixir 1.17.0`
-	Default	`1.18.4`

Version Normalization

migetpacks normalizes version constraints found in project files to Docker-compatible image tags. The following transformations are applied:

Prefix Removal

The v prefix is stripped from versions:

v20.11.0  ->  20.11.0

Semver Range Operators

Operators like >=, ^, ~, >, <, and = are removed, and the base version is extracted:

>=18       ->  18
^20.0.0    ->  20.0
~20.0.0    ->  20.0
>18        ->  18

For full semver versions with operators, the patch version is dropped:

^20.11.1   ->  20.11
~3.12.0    ->  3.12

Wildcard Patterns

The .x and .* patterns are reduced to the major version:

20.x       ->  20
22.*       ->  22

OR Alternatives

When a version string contains || separated alternatives, the highest major version is selected:

20.x || 22.x || 24.x   ->  24
>=18 || >=20            ->  20

Plain Versions

Explicit versions without operators are kept as-is, since Docker Hub has tags for all common formats:

       ->  20
11      ->  20.11
11.0    ->  20.11.0
12.8     ->  3.12.8

Getting Started

Guides

Configuration

Languages

Deploying

Reference

Detection Priority by Language

Node.js

Bun

Deno

Ruby

Python

Go

Rust

PHP

Java

Kotlin

Scala

Clojure

.NET

Elixir

Version Normalization

Prefix Removal

Semver Range Operators

Wildcard Patterns

OR Alternatives

Plain Versions

​Detection Priority by Language

​Node.js

​Bun

​Deno

​Ruby

​Python

​Go

​Rust

​PHP

​Java

​Kotlin

​Scala

​Clojure

​.NET

​Elixir

​Version Normalization

​Prefix Removal

​Semver Range Operators

​Wildcard Patterns

​OR Alternatives

​Plain Versions

Detection Priority by Language

Node.js

Bun

Deno

Ruby

Python

Go

Rust

PHP

Java

Kotlin

Scala

Clojure

.NET

Elixir

Version Normalization

Prefix Removal

Semver Range Operators

Wildcard Patterns

OR Alternatives

Plain Versions