Colin Watson has proposed merging
~cjwatson/launchpad:charm-db-update-fix-backend-connections into
launchpad:master.
Commit message:
charm: Fix launchpad-db-update's connections to backend databases
Requested reviews:
Launchpad code reviewers (launchpad-reviewers)
For more details, see:
https://code.launchpad.net/~cjwatson/launchpad/+git/launchpad/+merge/455782
The launchpad-db-update charm typically needs to connect directly to backend
databases, bypassing pgbouncer, because it needs to be able to disable ordinary
database access via pgbouncer before performing schema updates. I discovered
when testing this on staging that I hadn't quite got all the connection
arrangements for this right.
--
Your team Launchpad code reviewers is requested to review the proposed merge of
~cjwatson/launchpad:charm-db-update-fix-backend-connections into
launchpad:master.
diff --git a/charm/launchpad-db-update/config.yaml b/charm/launchpad-db-update/config.yaml
new file mode 100644
index 000..90cc41d
--- /dev/null
+++ b/charm/launchpad-db-update/config.yaml
@@ -0,0 +1,12 @@
+options:
+ backend_database_name:
+type: string
+description: >
+ Name of the database we are updating. (This must be the name of the
+ database as known to PostgreSQL, which is not necessarily the same as
+ that exposed by pgbouncer.)
+default: "launchpad_dev"
+ backend_database_user:
+type: string
+description: User name to use when connecting to backend databases.
+default: "postgres"
diff --git a/charm/launchpad-db-update/reactive/launchpad-db-update.py b/charm/launchpad-db-update/reactive/launchpad-db-update.py
index e9c4b06..0bb9806 100644
--- a/charm/launchpad-db-update/reactive/launchpad-db-update.py
+++ b/charm/launchpad-db-update/reactive/launchpad-db-update.py
@@ -21,8 +21,10 @@ from ols import base, postgres
from psycopg2.extensions import make_dsn, parse_dsn
-def any_dbname(dsn):
+def any_host_or_port_or_dbname(dsn):
parsed_dsn = parse_dsn(dsn)
+parsed_dsn["host"] = "*"
+parsed_dsn["port"] = "*"
parsed_dsn["dbname"] = "*"
return make_dsn(**parsed_dsn)
@@ -43,8 +45,11 @@ def configure():
db_admin = endpoint_from_flag("db-admin.master.available")
db_admin_primary, _ = postgres.get_db_uris(db_admin)
# We assume that this admin user works for any database on this host,
-# which seems to be true in practice.
-update_pgpass(any_dbname(db_admin_primary))
+# which seems to be true in practice. Indeed, since we need to bypass
+# pgbouncer and contact backend databases directly, assume that it works
+# for any host or port too so that we don't need to configure
+# credentials for all the database hosts individually.
+update_pgpass(any_host_or_port_or_dbname(db_admin_primary))
config["db_admin_primary"] = strip_dsn_authentication(db_admin_primary)
if is_flag_set("pgbouncer.master.available"):
diff --git a/charm/launchpad-db-update/templates/db-update.j2 b/charm/launchpad-db-update/templates/db-update.j2
index 4ca8e87..002933d 100755
--- a/charm/launchpad-db-update/templates/db-update.j2
+++ b/charm/launchpad-db-update/templates/db-update.j2
@@ -11,7 +11,9 @@ export LPCONFIG=launchpad-db-update
{% if pgbouncer_primary -%}
# Fastdowntime update, managing connections using pgbouncer.
{{ code_dir }}/database/schema/full-update.py \
---pgbouncer='{{ pgbouncer_primary }}'
+--pgbouncer='{{ pgbouncer_primary }}' \
+--dbname='{{ backend_database_name }}' \
+--dbuser='{{ backend_database_user }}'
{% else -%}
# We can't manage connections using pgbouncer in this environment. Attempt
# a simple schema upgrade, which may fail if anything has an active database
diff --git a/charm/launchpad-db-update/templates/preflight.j2 b/charm/launchpad-db-update/templates/preflight.j2
index ef2a88f..906938f 100755
--- a/charm/launchpad-db-update/templates/preflight.j2
+++ b/charm/launchpad-db-update/templates/preflight.j2
@@ -7,5 +7,7 @@
set -e
LPCONFIG=launchpad-db-update {{ code_dir }}/database/schema/preflight.py \
---skip-connection-check --pgbouncer='{{ pgbouncer_primary }}'
+--skip-connection-check --pgbouncer='{{ pgbouncer_primary }}' \
+--dbname='{{ backend_database_name }}' \
+--dbuser='{{ backend_database_user }}'
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