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Detection

migetpacks detects Go when any of these files are present in your project root:
  • go.mod
  • Godeps/Godeps.json
  • glide.yaml

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Version Detection

Go version is resolved in this order:
PrioritySourceExample
1GO_VERSION env varGO_VERSION=1.23
2.go-version file1.25.0
3go directive in go.modgo 1.23
4Default1.25.0

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Build Process

migetpacks generates a multi-stage Dockerfile that produces a static binary: 
# Builder stage
FROM golang:1.25 AS builder
WORKDIR /build

# Go build environment (static linking)
ENV CGO_ENABLED=0
ENV GOOS=linux

# Layer 1: Copy go.mod/go.sum for layer caching
COPY go.mod go.sum* ./

# Layer 2: Download dependencies (CACHED when go.mod unchanged)
RUN go mod download

# Layer 3: Copy source code
COPY . .

# Layer 4: Build static binary and cleanup
RUN go build -ldflags="-s -w" -o /build/myapp . \
    && rm -rf .git *.go go.mod go.sum vendor/

# Runtime stage
FROM debian:bookworm-slim
RUN apt-get update && apt-get install -y ca-certificates
WORKDIR /app
COPY --from=builder /build /app

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Static Linking

Go builds use CGO_ENABLED=0 by default, producing fully static binaries that run on minimal base images. The linker flags -s -w strip debug information for smaller binaries.

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Module Name and Binary Detection

The binary name is automatically derived from the module name in go.mod:
  • module github.com/user/myapp produces binary myapp
  • Falls back to app if detection fails

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Package Spec

You can specify which packages to build using the //+heroku install comment in go.mod: 
module github.com/user/myapp

// +heroku install ./cmd/api ./cmd/worker

go 1.23
Without this directive, go build . is used (builds the package in the current directory). For multiple packages, binaries are placed in /build/bin/: 
RUN go build -ldflags="-s -w" -o /build/bin/ ./cmd/...

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Build Hooks

migetpacks supports pre- and post-compile hooks:
  • bin/go-pre-compile - Runs before go build
  • bin/go-post-compile - Runs after go build

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golang-migrate

If github.com/golang-migrate/migrate is detected in go.mod, the migrate CLI tool is automatically installed in the builder stage.

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Linker Symbols

Set custom linker symbols using environment variables: 
-e GO_LINKER_SYMBOL=main.version -e GO_LINKER_VALUE=1.0.0
This adds -X main.version=1.0.0 to the linker flags.

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Run Command

The default run command is determined in this order:
PrioritySourceCommand
1RUN_COMMAND env varUser-specified
2web: in ProcfileFrom Procfile
3Default./app (or ./myapp based on module name)
Binary names in Procfiles are automatically prefixed with ./ if they don’t already have a path prefix.

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Caching

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Docker Layer Caching

Dependencies are downloaded in a separate layer. go mod download is only re-run when go.mod or go.sum changes.

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BuildKit Cache Mounts

When BUILD_CACHE_DIR is configured, BuildKit cache mounts are used:
Cache PathContents
/cache/goGo module cache (/go/pkg/mod) and build cache (~/.cache/go-build)

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Registry Cache

Use CACHE_IMAGE to push/pull BuildKit inline cache layers to a registry for cross-build caching.

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DHI Support

Go is supported with Docker Hardened Images (requires version 1.22 or later).
StageImage
Builddhi.io/golang:{version}-dev
Runtimedhi.io/golang:{version}
DHI images for Go require minimum patch versions: 1.22.12, 1.23.7, or 1.24.1+. Older patch versions within these minor releases are not available.
The DHI runtime image is distroless with no shell. Since Go produces static binaries, this works without any special handling.

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Go Toolchain in Runtime

If you need the Go toolchain available at runtime (for plugins, go run, etc.): 
-e GO_INSTALL_TOOLS_IN_IMAGE=true
This copies /usr/local/go from the builder to the runtime image.

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Example

docker run --rm \
  -v /path/to/app:/workspace/source \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -e OUTPUT_IMAGE=my-go-app:latest \
  miget/migetpacks:latest

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With Custom Options

docker run --rm \
  -v /path/to/app:/workspace/source \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -e OUTPUT_IMAGE=registry.io/app:v1 \
  -e GO_VERSION=1.23 \
  -e GO_LINKER_SYMBOL=main.version \
  -e GO_LINKER_VALUE=1.2.3 \
  -e USE_DHI=true \
  miget/migetpacks:latest

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Multi-Binary Project

docker run --rm \
  -v /path/to/app:/workspace/source \
  -v /var/run/docker.sock:/var/run/docker.sock \
  -e OUTPUT_IMAGE=registry.io/app:v1 \
  -e RUN_COMMAND="./bin/api" \
  miget/migetpacks:latest
With // +heroku install ./cmd/api ./cmd/worker in go.mod, both binaries are available at /app/bin/api and /app/bin/worker.