Everything below is one project, built from an ordinary repository with no

Gagarin-specific anything in it. No manifest, no config file, no YAML: there is

nowhere on this platform to put one, which is the point and is also why this post

is short.

The app is a Go API, a web front end that calls it, and a Postgres under both.

Call the project feed .

1. The Dockerfile is the only file we need

If your repository already builds an image, you are done before you start. Ours

is the usual two-stage build:

FROM golang:1.25-alpine AS build WORKDIR /src COPY go.mod go.sum ./ RUN go mod download COPY . . RUN CGO_ENABLED = 0 go build -o /out/feed ./cmd/feed

FROM gcr.io/distroless/static:nonroot COPY --from=build /out/feed /feed EXPOSE 8080 USER nonroot ENTRYPOINT ["/feed"]

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Two things about it matter here and nothing else does. It listens on one TCP

port , and it reads its configuration from the environment.…