Allow upgrade from 14 to 15

Dockerfile

@@ -7,14 +7,16 @@ RUN go mod download
 
 RUN mkdir bin/ && go build -o bin/ ./...
 
-FROM postgis/postgis:16-master
+FROM postgis/postgis:15-3.4
 
 COPY --from=builder /usr/local/src/pg_autoconfig/bin/pg_autoconfig /
 
 COPY upgrade-entrypoint.sh /
 
 RUN localedef -i cs_CZ -c -f UTF-8 -A /usr/share/locale/locale.alias cz_CZ.UTF-8 && \
-	apt-get update && apt-get install -y postgresql-16-auto-failover pg-auto-failover-cli postgresql-16-pgvector && \
+	apt-get update && apt-get install -y postgresql-15-auto-failover pg-auto-failover-cli postgresql-15-pgvector \
+	# Include previous postgres version to allow automatic upgrade
+	postgresql-14 postgresql-14-postgis-3 postgresql-14-pgvector && \
 	rm -rf /var/lib/apt/lists/* && \
 	chmod +x /upgrade-entrypoint.sh
 

upgrade-entrypoint.sh

@@ -3,7 +3,9 @@ set -e
 
 DATA_DIR="/var/lib/postgresql/data"
 OLD_VERSION_FILE="$DATA_DIR/PG_VERSION"
-NEW_VERSION="16"
+NEW_VERSION="15"
+OLD_BIN="/usr/lib/postgresql/14/bin"
+NEW_BIN="/usr/lib/postgresql/15/bin"
 
 if [ -f "$OLD_VERSION_FILE" ]; then
     OLD_VERSION=$(cat "$OLD_VERSION_FILE")
@@ -27,8 +29,8 @@ if [ -f "$OLD_VERSION_FILE" ]; then
         pg_upgrade \
             -d $DATA_DIR/old_data \
             -D $DATA_DIR/new_data \
-            -b /usr/bin/postgres-16 \
-            -B /usr/local/bin \
+            -b "$OLD_BIN" \
+            -B "$NEW_BIN" \
             --link
         
 				# Clean-up