use build args instead of templating

Dockerfile

@@ -0,0 +1,27 @@
+ARG ALPINE_VERSION
+FROM alpine:${ALPINE_VERSION}
+
+ADD src/install.sh install.sh
+RUN sh install.sh && rm install.sh
+
+ENV POSTGRES_DATABASE ''
+ENV POSTGRES_HOST ''
+ENV POSTGRES_PORT 5432
+ENV POSTGRES_USER ''
+ENV POSTGRES_PASSWORD ''
+ENV PGDUMP_EXTRA_OPTS ''
+ENV S3_ACCESS_KEY_ID ''
+ENV S3_SECRET_ACCESS_KEY ''
+ENV S3_BUCKET ''
+ENV S3_REGION 'us-west-1'
+ENV S3_PATH 'backup'
+ENV S3_ENDPOINT ''
+ENV S3_S3V4 'no'
+ENV SCHEDULE ''
+ENV PASSPHRASE ''
+
+ADD src/run.sh run.sh
+ADD src/backup.sh backup.sh
+ADD src/restore.sh restore.sh
+
+CMD ["sh", "run.sh"]