Initial version

Dockerfile

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+FROM alpine:latest as prefetch
+
+RUN set -ex \
+ && apk --no-cache add \
+     curl \
+ && mkdir -p /src \
+ && curl -sSfLo /src/dumb-init "https://github.com/Yelp/dumb-init/releases/download/v1.2.2/dumb-init_1.2.2_amd64" \
+ && chmod 0755 /src/dumb-init
+
+
+FROM postgres:9.6
+
+COPY --from=prefetch  /src/dumb-init  /usr/local/bin/dumb-init
+COPY                  pgbackup.sh     /usr/local/bin/pgbackup.sh
+
+ENTRYPOINT ["/usr/local/bin/dumb-init"]
+CMD ["/bin/bash", "/usr/local/bin/pgbackup.sh"]

pgbackup.sh

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+#!/bin/bash
+set -euo pipefail
+
+if [[ -z ${PGPASSWORD:-} ]]; then
+	echo 'No $PGPASSWORD was present, aborting.'
+	exit 1
+fi
+
+set -x # Do NOT set earlier not to log the password
+
+# Remove old backups older than N days (default 2d)
+DELETE_OLDER_THAN=${DELETE_OLDER_THAN:-2}
+
+# This directory is exposed by the postgres image
+TARGET_DIR="${TARGET_DIR:-/var/lib/postgresql/data}"
+
+# Set defaults for PostgreSQL connect
+PGHOST="${PGHOST:-postgres}"
+PGUSER="${PGUSER:-postgres}"
+
+while [ 1 ]; do
+
+	BACKUP_DATE=$(date +%Y-%m-%d_%H-%M-%S)
+
+	pg_dumpall -h "${PGHOST}" -U "${PGUSER}" -g -f "${TARGET_DIR}/${BACKUP_DATE}_globals.sql"
+	gzip "${TARGET_DIR}/${BACKUP_DATE}_globals.sql"
+
+	# Create backup
+	for dbname in $(psql -h "${PGHOST}" -U "${PGUSER}" -q -A -t -c "SELECT datname FROM pg_database" | grep -vE 'template[01]'); do
+		TARGET_FILE="${TARGET_DIR}/${BACKUP_DATE}_${dbname}.sql"
+		pg_dump -h "${PGHOST}" -U "${PGUSER}" -C "${dbname}" >"${TARGET_FILE}"
+		gzip "${TARGET_FILE}"
+	done
+
+	# Cleanup old backups
+	find "${TARGET_DIR}" -mtime "${DELETE_OLDER_THAN}" \( -name '*.sql.gz' -or -name '*.sql' \) -delete
+
+	# Sleep until next full hour
+	sleep $((3600 - $(date +%s) % 3600))
+
+done