Fixes #37874 - don't try to swap modules, this can fail

instead use single-user mode cluster based on the postgresql-upgrade
binaries

hooks/boot/06-postgresql-upgrade-extensions.rb

@@ -1,5 +1,3 @@
-require 'csv'
-
 module PostgresqlUpgradeHookContextExtension
   def needs_postgresql_upgrade?(new_version)
     current_version.to_i < new_version.to_i
@@ -18,12 +16,6 @@ def os_needs_postgresql_upgrade?
   def postgresql_upgrade(new_version)
     logger.notice("Performing upgrade of PostgreSQL to #{new_version}")
 
-    execute!("dnf module switch-to postgresql:#{current_version} -y", false, true)
-    start_services(['postgresql'])
-    postgres_list = `runuser -l postgres -c 'psql --list --tuples-only --csv'`
-    postgres_databases = CSV.parse(postgres_list)
-    (_name, _owner, _enconding, collate, ctype, _privileges) = postgres_databases.find { |line| line.first == 'postgres' }
-
     stop_services
 
     logger.notice("Upgrading PostgreSQL packages")
@@ -41,6 +33,20 @@ def postgresql_upgrade(new_version)
 
     logger.notice("Migrating PostgreSQL data")
 
+    # We need to know the collation and ctype of the DB as postgresql-setup --upgrade
+    # doesn't detect those on its own: https://issues.redhat.com/browse/RHEL-58410
+    # dnf switch-to has already replaced the packages and the cluster is down
+    # We have to start the cluster in single-user mode with the old postgres binary
+    postgres_result = `echo "select datcollate,datctype from pg_database where datname='postgres';" | runuser -l postgres -c '/usr/lib64/pgsql/postgresql-#{current_version}/bin/postgres --single -D /var/lib/pgsql/data postgres'`
+    data = {}
+    postgres_result.each_line do |line|
+      line.match(/dat(collate|ctype)\s+=\s+(\S+)/) do |m|
+        data[m[1]] = m[2].delete('"')
+      end
+    end
+    collate = data['collate']
+    ctype = data['ctype']
+
     # puppetlabs-postgresql always sets data_directory in the config
     # see https://github.com/puppetlabs/puppetlabs-postgresql/issues/1576
     # however, one can't use postgresql-setup --upgrade if that value is set

spec/postgresql_upgrade_hook_context_extension_spec.rb

@@ -37,21 +37,16 @@
       allow(context).to receive(:ensure_packages)
       allow(context).to receive(:stop_services)
       allow(context).to receive(:start_services)
-      allow(context).to receive(:'`').with("runuser -l postgres -c 'psql --list --tuples-only --csv'")
+      allow(context).to receive(:'`').with("echo \"select datcollate,datctype from pg_database where datname='postgres';\" | runuser -l postgres -c '/usr/lib64/pgsql/postgresql-12/bin/postgres --single -D /var/lib/pgsql/data postgres'")
                                      .and_return(<<~PSQL
-        candlepin,postgres,UTF8,en_US.utf8,en_US.utf8,"=T/postgres
-        postgres=CTc/postgres
-        candlepin=CTc/postgres"
-        foreman,foreman,UTF8,en_US.utf8,en_US.utf8,"=T/foreman
-        foreman=CTc/foreman"
-        postgres,postgres,UTF8,en_US.UTF-8,en_US.UTF-8,
-        pulpcore,postgres,UTF8,en_US.utf8,en_US.utf8,"=T/postgres
-        postgres=CTc/postgres
-        pulp=CTc/postgres"
-        template0,postgres,UTF8,en_US.UTF-8,en_US.UTF-8,"=c/postgres
-        postgres=CTc/postgres"
-        template1,postgres,UTF8,en_US.UTF-8,en_US.UTF-8,"=c/postgres
-        postgres=CTc/postgres"
+        PostgreSQL stand-alone backend 12.18
+        backend> 	 1: datcollate	(typeid = 19, len = 64, typmod = -1, byval = f)
+        	 2: datctype	(typeid = 19, len = 64, typmod = -1, byval = f)
+        	----
+        	 1: datcollate = "en_US.UTF-8"	(typeid = 19, len = 64, typmod = -1, byval = f)
+        	 2: datctype = "en_US.UTF-8"	(typeid = 19, len = 64, typmod = -1, byval = f)
+        	----
+        backend>
       PSQL
                                                 )
       allow(logger).to receive(:notice)