Ignore known restore from backup errors

The Omnibus user does not have access to create or drop extensions or
schema. We can ignore these errors since they shouldn't change restore
from backup.

In addition, flush the output so that the prompt shows up.

lib/backup/database.rb

@@ -8,6 +8,14 @@ module Backup
     attr_reader :progress
     attr_reader :config, :db_file_name
 
+    IGNORED_ERRORS = [
+      # Ignore the DROP errors; recent database dumps will use --if-exists with pg_dump
+      /does not exist$/,
+      # User may not have permissions to drop extensions or schemas
+      /must be owner of/
+    ].freeze
+    IGNORED_ERRORS_REGEXP = Regexp.union(IGNORED_ERRORS).freeze
+
     def initialize(progress, filename: nil)
       @progress = progress
       @config = YAML.load_file(File.join(Rails.root, 'config', 'database.yml'))[Rails.env]
@@ -49,6 +57,8 @@ module Backup
       end
 
       report_success(success)
+      progress.flush
+
       raise Backup::Error, 'Backup failed' unless success
     end
 
@@ -83,6 +93,10 @@ module Backup
 
     protected
 
+    def ignore_error?(line)
+      IGNORED_ERRORS_REGEXP.match?(line)
+    end
+
     def execute_and_track_errors(cmd, decompress_rd)
       errors = []
 
@@ -97,8 +111,7 @@ module Backup
         Thread.new do
           until (raw_line = stderr.gets).nil?
             warn(raw_line)
-            # Recent database dumps will use --if-exists with pg_dump
-            errors << raw_line unless raw_line =~ /does not exist$/
+            errors << raw_line unless ignore_error?(raw_line)
           end
         end
 

spec/lib/backup/database_spec.rb

@@ -38,7 +38,7 @@ RSpec.describe Backup::Database do
 
     context 'when the restore command prints errors' do
       let(:visible_error) { "This is a test error\n" }
-      let(:noise) { "Table projects does not exist\n" }
+      let(:noise) { "Table projects does not exist\nmust be owner of extension pg_trgm\n" }
       let(:cmd) { %W[#{Gem.ruby} -e $stderr.write("#{noise}#{visible_error}")] }
 
       it 'filters out noise from errors' do