How to fix Dockerfile parse error line 10: MAINTAINER is deprecated in Docker

DockerBEGINNERLOW

This warning appears when Docker encounters the deprecated MAINTAINER instruction in your Dockerfile. Replace it with the LABEL instruction using the org.opencontainers.image.authors key to specify maintainer metadata following modern OCI standards.

What this error means

The MAINTAINER instruction was historically used in Dockerfiles to specify the author or maintainer of an image. However, this instruction has been deprecated since Docker 1.13.0 in favor of the more flexible LABEL instruction. When Docker parses your Dockerfile and encounters MAINTAINER, it will display a deprecation warning. While the build may still succeed, the warning indicates you're using an outdated practice that may be removed in future Docker versions. The deprecation exists because LABEL provides a standardized, more powerful approach to image metadata. Unlike MAINTAINER (which only accepts a single string), LABEL supports arbitrary key-value pairs, follows the OCI (Open Container Initiative) specification, and can be easily queried using `docker inspect`.

How to fix "Dockerfile parse error line 10: MAINTAINER is deprecated"

1Locate the MAINTAINER instruction

First, find the MAINTAINER line in your Dockerfile. It typically appears near the top, after the FROM instruction:

dockerfile

FROM ubuntu:22.04
MAINTAINER John Doe <[email protected]>

You can search for it with:

bash

grep -n "MAINTAINER" Dockerfile

2Replace MAINTAINER with LABEL

Replace the MAINTAINER instruction with LABEL using the standardized OCI key for author information.

Before (deprecated):

dockerfile

FROM ubuntu:22.04
MAINTAINER John Doe <[email protected]>

After (recommended - OCI standard):

dockerfile

FROM ubuntu:22.04
LABEL org.opencontainers.image.authors="John Doe <[email protected]>"

Alternative (simpler):

dockerfile

FROM ubuntu:22.04
LABEL maintainer="[email protected]"

The OCI standard (org.opencontainers.image.authors) is preferred for maximum compatibility with container tools and registries.

3Handle multiple maintainers

If you have multiple maintainers, include them in a single LABEL:

dockerfile

LABEL org.opencontainers.image.authors="John Doe <[email protected]>, Jane Smith <[email protected]>"

Or use multiple labels for different purposes:

dockerfile

LABEL org.opencontainers.image.authors="Team Name <[email protected]>"
LABEL org.opencontainers.image.vendor="Company Name"
LABEL org.opencontainers.image.url="https://github.com/company/project"

4Add additional OCI labels (optional)

While updating your Dockerfile, consider adding other useful OCI standard labels:

dockerfile

LABEL org.opencontainers.image.authors="[email protected]"
LABEL org.opencontainers.image.title="My Application"
LABEL org.opencontainers.image.description="A containerized web application"
LABEL org.opencontainers.image.version="1.0.0"
LABEL org.opencontainers.image.source="https://github.com/user/repo"
LABEL org.opencontainers.image.licenses="MIT"

Or combine them in a single LABEL instruction:

dockerfile

LABEL org.opencontainers.image.authors="[email protected]" \
      org.opencontainers.image.title="My Application" \
      org.opencontainers.image.version="1.0.0"

5Verify the fix

Rebuild your image to confirm the warning is gone:

bash

docker build -t myimage:latest .

You can verify the labels are set correctly:

bash

docker inspect myimage:latest --format='{{json .Config.Labels}}' | jq

Or without jq:

bash

docker inspect myimage:latest | grep -A 10 '"Labels"'

Run hadolint to check for other Dockerfile issues:

bash

docker run --rm -i hadolint/hadolint < Dockerfile

Advanced notes

### OCI Image Specification Labels

The Open Container Initiative (OCI) defines standard label keys for container image metadata. Using these ensures compatibility across container runtimes and registries:

| Label | Purpose |
|-------|---------|
| org.opencontainers.image.authors | Contact details of maintainers |
| org.opencontainers.image.title | Human-readable title |
| org.opencontainers.image.description | Human-readable description |
| org.opencontainers.image.version | Version of the packaged software |
| org.opencontainers.image.source | URL to source code |
| org.opencontainers.image.licenses | License(s) under which contained software is distributed |
| org.opencontainers.image.vendor | Name of the distributing entity |
| org.opencontainers.image.created | Date and time on which the image was built (RFC 3339) |

### Dynamic Labels at Build Time

You can set labels dynamically using build arguments:

dockerfile

ARG BUILD_DATE
ARG VERSION
ARG VCS_REF

LABEL org.opencontainers.image.created="${BUILD_DATE}" \
      org.opencontainers.image.version="${VERSION}" \
      org.opencontainers.image.revision="${VCS_REF}"

Then build with:

bash

docker build \
  --build-arg BUILD_DATE=$(date -u +'%Y-%m-%dT%H:%M:%SZ') \
  --build-arg VERSION=1.0.0 \
  --build-arg VCS_REF=$(git rev-parse --short HEAD) \
  -t myimage:latest .

### Querying Labels

Labels can be used to filter and organize images:

bash

# Find images by author
docker images --filter "[email protected]"

# List all labels for an image
docker inspect --format='{{range $k, $v := .Config.Labels}}{{$k}}={{$v}}{{println}}{{end}}' myimage:latest

### Why MAINTAINER Was Deprecated

The MAINTAINER instruction had several limitations:
1. Only supported a single string value
2. Not part of the OCI specification
3. Couldn't be filtered or queried easily
4. No standardized format for the value
5. Mixing author info with other metadata wasn't possible

LABEL solves all these issues while providing a standardized, extensible approach to image metadata.

How to fix Dockerfile parse error line 10: MAINTAINER is deprecated in Docker

What this error means

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Common causes

How to fix "Dockerfile parse error line 10: MAINTAINER is deprecated"

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