Implement builder image

Add docker build to create a shared image for running CI pipelines and
docker builds based on debian.

.gitlab-ci.yml

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+default:
+  image: docker:24.0.5
+
+build:
+  stage: build
+  script:
+    - docker build $CI_PROJECT_DIR
+      --tag ${REGISTRY_IMAGE}:${CI_COMMIT_REF_SLUG}
+      $(echo "$CI_COMMIT_TAG" | if grep -q $(date -u '+^r%g\.%-V\.\(0\|[1-9][0-9]*\)$');
+        then echo --tag ${REGISTRY_IMAGE}:latest;
+      fi)
+
+deploy:
+  stage: deploy
+  script:
+    - echo "$REGISTRY_PASSWORD" | docker login $CI_REGISTRY -u $REGISTRY_USER --password-stdin
+    - docker push --all-tags ${REGISTRY_IMAGE}

Dockerfile

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+FROM debian:bookworm
+
+RUN set -eux; \
+	apt-get update; \
+	apt-get install -y --no-install-recommends \
+		ca-certificates \
+		curl \
+		git \
+	; \
+	install -m 0755 -d /etc/apt/keyrings; \
+	curl -sSL https://download.docker.com/linux/debian/gpg -o /etc/apt/keyrings/docker.asc; \
+	chmod a+r /etc/apt/keyrings/docker.asc; \
+	echo \
+		"deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] \
+		https://download.docker.com/linux/debian \
+		bookworm stable" \
+	> /etc/apt/sources.list.d/docker.list; \
+	apt-get update; \
+	apt-get install -y --no-install-recommends \
+		docker-ce-cli \
+		docker-buildx-plugin \
+		docker-compose-plugin \
+	; \
+	rm -rf /var/lib/apt/lists/*
+
+# References:
+# - docker: https://docs.docker.com/engine/install/debian/#install-from-a-package

Readme.md

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+# Builder
+
+Common docker image used for running application builds, CI pipelines, and deployment scripts based on Debian 12.
+
+## Tools included
+
+- `docker`
+- `curl`
+- `git`

tag-release.sh

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+#!/bin/bash
+
+# Finds the next available r<year>.<week>.<bump> identifier for the current year and week
+YEAR_WEEK=$(date -u +%g.%-V)
+YEAR=${YEAR_WEEK:0:2}
+WEEK=${YEAR_WEEK:3}
+LAST_BUMP=$(git tag --list | grep '^r'$YEAR'\.'$WEEK'\.\(0\|[1-9][0-9]*\)$' | cut -d . -f 3 | sort -nr | head -n 1)
+RELEASE=r${YEAR_WEEK}.$(( ${LAST_BUMP:--1} + 1 ))
+
+git tag $RELEASE
+echo Tagged $RELEASE