Communities

Writing
Writing
Codidact Meta
Codidact Meta
The Great Outdoors
The Great Outdoors
Photography & Video
Photography & Video
Scientific Speculation
Scientific Speculation
Cooking
Cooking
Electrical Engineering
Electrical Engineering
Judaism
Judaism
Languages & Linguistics
Languages & Linguistics
Software Development
Software Development
Mathematics
Mathematics
Christianity
Christianity
Code Golf
Code Golf
Music
Music
Physics
Physics
Linux Systems
Linux Systems
Power Users
Power Users
Tabletop RPGs
Tabletop RPGs
Community Proposals
Community Proposals
tag:snake search within a tag
answers:0 unanswered questions
user:xxxx search by author id
score:0.5 posts with 0.5+ score
"snake oil" exact phrase
votes:4 posts with 4+ votes
created:<1w created < 1 week ago
post_type:xxxx type of post
Search help
Notifications
Mark all as read See all your notifications »
Q&A

Welcome to Software Development on Codidact!

Will you help us build our independent community of developers helping developers? We're small and trying to grow. We welcome questions about all aspects of software development, from design to code to QA and more. Got questions? Got answers? Got code you'd like someone to review? Please join us.

UID of nonroot user in distroless container images

+0
−0

Distroless images use a user called nonroot by convention. What's the UID (User ID) of this user?

This is relevant in multi-stage image builds:

FROM bash:latest as builder

RUN adduser adduser \
  --disabled-password \
  --gecos "" \
  --home "/nonexistent" \
  --shell "/sbin/nologin" \
  --no-create-home \
  --uid "???" \
  "nonroot"
USER nonroot

WORKDIR /app

# Simulating a build here
RUN echo binary > executable


# A distroless base image for static executables.
# It uses the nonroot user:
# https://edu.chainguard.dev/chainguard/chainguard-images/reference/glibc-dynamic/image_specs/
FROM cgr.dev/chainguard/cc-dynamic:latest

WORKDIR /app

COPY --from builder /app/executable ./

CMD "/app/executable"

The UIDs need to match in the builder stage and the final image.

History
Why does this post require moderator attention?
You might want to add some details to your flag.
Why should this post be closed?

0 comment threads

2 answers

+0
−0

You don't actually need the UID in that particular example.

A more elegant solution would be to use the --chown option of the COPY directive.

FROM bash:latest as builder

RUN adduser adduser \
  --disabled-password \
  --gecos "" \
  --home "/nonexistent" \
  --shell "/sbin/nologin" \
  --no-create-home \
  "nonroot"
USER nonroot

WORKDIR /app

# Simulating a build here
RUN echo binary > executable


# A distroless base image for static executables.
# It uses the nonroot user:
# https://edu.chainguard.dev/chainguard/chainguard-images/reference/glibc-dynamic/image_specs/
FROM cgr.dev/chainguard/cc-dynamic:latest

WORKDIR /app

# This eliminates the need for UIDs.
COPY --from builder --chown=nonroot /app/executable ./

CMD "/app/executable"
History
Why does this post require moderator attention?
You might want to add some details to your flag.

0 comment threads

+0
−0

The UID of nonroot user is 65532.

This is by convention.

I failed to find a reputable source for this, but looking around image internals, it seems to hold.

History
Why does this post require moderator attention?
You might want to add some details to your flag.

0 comment threads

Sign up to answer this question »