Install libldap-2.5 explicitly when installing synapse-s3-storage-provider to satisfy its psycopg2 dependency

Author: spantaleev

roles/custom/matrix-synapse/defaults/main.yml

@@ -52,6 +52,26 @@ matrix_synapse_container_image_customizations_s3_storage_provider_installation_e
 # https://github.com/aws/aws-cli/issues/9214
 matrix_synapse_container_image_customizations_s3_storage_provider_installation_old_boto_workaround_enabled: true
 
+# Controls whether to install libldapXX explicitly when installing s3-storage-provider.
+# This is to work around it potentially not being there (after `autoremove` invoked by other scripts cleans it up, etc.)
+#
+# Some scripts in the custom Dockerfile may install and then autoremove git/ssh/openssh-client.
+# This has the side-effect of removing the libldap library that s3-storage-provider depends upon indirectly (via psycopg2).
+#
+# If this should happen, s3-storage-provider (the `s3_media_upload` script) will fail to start with an error like this:
+# > Traceback (most recent call last):
+# >   File "/usr/local/bin/s3_media_upload", line 10, in <module>
+# >     import psycopg2
+# >   File "/usr/local/lib/python3.12/site-packages/psycopg2/__init__.py", line 51, in <module>
+# >     from psycopg2._psycopg import (                     # noqa
+# > ImportError: libldap-2.5.so.0: cannot open shared object file: No such file or directory
+#
+# The library (e.g. `/usr/lib/x86_64-linux-gnu/libldap-2.5.so.0`) appears to be available by default in the upstream Synapse image for some reason,
+# but it doesn't seem to be installed through a Debian package. Autoremoval would remove it, causing s3-storage-provider to fail.
+# Given that this is a dependency for s3-storage-provider (psycopg2), we prefer to install it explicitly.
+matrix_synapse_container_image_customizations_s3_storage_provider_installation_explicit_libldap_installation_enabled: true
+matrix_synapse_container_image_customizations_s3_storage_provider_installation_explicit_libldap_installation_package_name: libldap-2.5
+
 # Controls whether custom build steps will be added to the Dockerfile for installing auto-accept-invite module.
 # The version that will be installed is specified in `matrix_synapse_ext_synapse_auto_accept_invite_version`.
 matrix_synapse_container_image_customizations_auto_accept_invite_installation_enabled: "{{ matrix_synapse_ext_synapse_auto_accept_invite_enabled }}"

roles/custom/matrix-synapse/templates/synapse/customizations/Dockerfile.j2

@@ -11,6 +11,9 @@ RUN pip install 'boto3<1.36.0' 'botocore<1.36.0' synapse-s3-storage-provider=={{
 {% else %}
 RUN pip install synapse-s3-storage-provider=={{ matrix_synapse_ext_synapse_s3_storage_provider_version }}
 {% endif %}
+{% if matrix_synapse_container_image_customizations_s3_storage_provider_installation_explicit_libldap_installation_enabled %}
+RUN apt-get update && apt-get install --no-install-recommends -y {{ matrix_synapse_container_image_customizations_s3_storage_provider_installation_explicit_libldap_installation_package_name }}
+{% endif %}
 {% endif %}
 
 {% if matrix_synapse_container_image_customizations_templates_enabled %}