What is in the image

Base	ghcr.io/cloudnative-pg/postgresql:17.7-standard-bookworm
PostgreSQL	17.7
pg_duckdb	1.1.0, staged from pgduckdb/pgduckdb:17-v1.1.1
pgvector	0.8.1, from the CloudNativePG standard base
Platforms	linux/amd64, linux/arm64

The pg_duckdb extension version (1.1.0) and the image it is staged from (v1.1.1) genuinely differ — the tag names the upstream image release, the extension inside it reports 1.1.0.

What the build adds

The Dockerfile adds two things to the CloudNativePG base:

• pg_duckdb. Its runtime artifacts (libduckdb.so, pg_duckdb.so, bitcode, and extension SQL) are copied from the official pg_duckdb image, and pg_duckdb is appended to shared_preload_libraries in postgresql.conf.sample. PostgreSQL copies that sample when it initializes a data directory, which is how the standalone path gets the preload for free — and why the CloudNativePG path, which generates its own configuration, does not.
• The standard PostgreSQL entrypoint. docker-entrypoint.sh, the initdb helpers, and gosu are staged in so the image also runs under a plain docker run, not only under the CloudNativePG operator.

One init script, initdb.d/0000-install-extensions.sql, is installed into /docker-entrypoint-initdb.d/. The standard entrypoint runs it the first time a data directory is initialized, which issues:

CREATE EXTENSION IF NOT EXISTS vector;
CREATE EXTENSION IF NOT EXISTS pg_duckdb;

Both mechanisms — the sample config and the init directory — belong to the stock entrypoint, so they apply to the standalone path only. Under CloudNativePG the Cluster manifest carries the equivalent settings; see Run the image.

Checking a running container

Against a standalone container started as in Run the image:

psql "postgres://postgres:password@localhost:5432/postgres" \
  -c "show shared_preload_libraries;"

 shared_preload_libraries
--------------------------
 pg_duckdb

Both extensions answer queries:

psql "postgres://postgres:password@localhost:5432/postgres" \
  -c "select '[1,2,3]'::vector <-> '[3,2,1]'::vector as l2;" \
  -c "select * from duckdb.query('select 42 as answer');"

         l2
--------------------
 2.8284271247461903
(1 row)

 answer
--------
     42
(1 row)