build: halt build if PG can have a minor upgrade (#76)

When building the image, we start from a PostGIS community image. There
is a chance that newer PostgreSQL packages are released after image
release, and they could be upgraded installing extensions. We want to
prevent this scenario, as it could lead to unexpected versions in the
container image.

Closes #75

Signed-off-by: Francesco Canovai <[email protected]>

Author: fcanovai

PostGIS/Dockerfile.template

@@ -31,6 +31,11 @@ COPY requirements.txt /
 # Install additional extensions
 RUN set -xe; \
 	apt-get update; \
+	if apt list --upgradable 2>/dev/null | grep -q '^postgres'; then \
+		echo "ERROR: Upgradable postgres packages found!"; \
+		apt list --upgradable 2>/dev/null | grep '^postgres'; \
+		exit 1; \
+	fi; \
 	apt-get install -y --no-install-recommends \
 		"postgresql-${PG_MAJOR}-pgaudit" \
 		"postgresql-${PG_MAJOR}-pg-failover-slots" \