Docker notes

cbrake · January 20, 2022, 2:33pm

Interesting Dockerfile example with separate build/image stages:

benbjohnson/litestream-s6-example/blob/main/Dockerfile

# Use the Go image to build our application.
FROM golang:1.16 as builder

# Copy the present working directory to our source directory in Docker.
COPY . /src/myapp

# Change the current directory in Docker to our source directory.
WORKDIR /src/myapp

# Build our application as a static build.
# The mount options add the build cache to Docker to speed up multiple builds.
RUN --mount=type=cache,target=/root/.cache/go-build \
	--mount=type=cache,target=/go/pkg \
	go build -ldflags '-s -w -extldflags "-static"' -tags osusergo,netgo,sqlite_omit_load_extension -o /usr/local/bin/myapp .

# Download the static build of Litestream directly into the path & make it executable.
# This is done in the builder and copied as the chmod doubles the size.
ADD https://github.com/benbjohnson/litestream/releases/download/v0.3.7/litestream-v0.3.7-linux-amd64-static.tar.gz /tmp/litestream.tar.gz
RUN tar -C /usr/local/bin -xzf /tmp/litestream.tar.gz

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This example uses s6 for monitoring processes.