---
title: "Build Metadata"
description: "Git provenance and builder facts emitted on every build"
---

## Overview

migetpacks records who built an image and from which commit, then exposes that
on four surfaces:

- The `build` block in the [result JSON](/reference/result-json).
- OCI image labels you can read with `docker inspect` without running the image.
- An in-image file `/.miget/build.json` (buildpack builds).
- `MIGET_*` build args for custom Dockerfile and Compose builds.

## Sources

Each field resolves by precedence, highest first:

1. The `build-meta` input envelope (set by the platform).
2. `MIGET_GIT_*` or `SOURCE_VERSION` environment variables, for standalone
   `docker run` or CI builds.
3. `.git` autodetection of the source directory.

Unknown fields are omitted rather than set to empty strings.

## OCI labels

| Label | Value |
|-------|-------|
| `org.opencontainers.image.revision` | Full commit SHA |
| `org.opencontainers.image.source` | Repository URL |
| `org.opencontainers.image.created` | Build time (ISO 8601) |
| `com.miget.git.branch` | Branch |
| `com.miget.git.description` | Commit subject |
| `com.miget.builder.version` | migetpacks version |

```bash
docker inspect my-app:latest --format '{{json .Config.Labels}}'
```

## In-image file

Buildpack builds include `/.miget/build.json`, useful when you prefer a file
over environment variables or run a distroless image with no shell:

```bash
docker run --rm my-app:latest cat /.miget/build.json
```

## Custom Dockerfile and Compose builds

migetpacks does not modify a Dockerfile it does not own, so it passes the values
as build args. Opt in from your Dockerfile:

```dockerfile
ARG MIGET_GIT_COMMIT
ENV MIGET_GIT_COMMIT=${MIGET_GIT_COMMIT}
```