Module: PgEasyReplicate

Extended by:
Helper
Defined in:
lib/pg_easy_replicate.rb,
lib/pg_easy_replicate/cli.rb,
lib/pg_easy_replicate/group.rb,
lib/pg_easy_replicate/query.rb,
lib/pg_easy_replicate/stats.rb,
lib/pg_easy_replicate/helper.rb,
lib/pg_easy_replicate/version.rb,
lib/pg_easy_replicate/orchestrate.rb,
lib/pg_easy_replicate/index_manager.rb

Defined Under Namespace

Modules: Helper, IndexManager Classes: CLI, Error, Group, Orchestrate, Query, Stats

Constant Summary collapse

SCHEMA_FILE_LOCATION = 
"/tmp/pger_schema.sql"
VERSION = 
"0.2.4"

Class Method Summary collapse

Methods included from Helper

abort_with, connection_info, db_name, db_user, determine_tables, internal_schema_name, internal_user_name, list_all_tables, logger, publication_name, quote_ident, secondary_source_db_url, source_db_url, subscription_name, target_db_url, test_env?, underscore

Class Method Details

.assert_config(special_user_role: nil, copy_schema: false, tables: "", schema_name: nil) ⇒ Object 



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# File 'lib/pg_easy_replicate.rb', line 76

def assert_config(
  special_user_role: nil,
  copy_schema: false,
  tables: "",
  schema_name: nil
)
  config_hash =
    config(
      special_user_role: special_user_role,
      copy_schema: copy_schema,
      tables: tables,
      schema_name: schema_name,
    )

  if copy_schema && !config_hash.dig(:pg_dump_exists)
    abort_with("pg_dump must exist if copy_schema (-c) is passed")
  end

  unless assert_wal_level_logical(config_hash.dig(:source_db))
    abort_with("WAL_LEVEL should be LOGICAL on source DB")
  end

  unless assert_wal_level_logical(config_hash.dig(:target_db))
    abort_with("WAL_LEVEL should be LOGICAL on target DB")
  end

  unless config_hash.dig(:source_db_is_super_user)
    abort_with("User on source database does not have super user privilege")
  end

  if tables.split(",").size > 0 && (schema_name.nil? || schema_name == "")
    abort_with("Schema name is required if tables are passed")
  end

  unless config_hash.dig(:tables_have_replica_identity)
    abort_with(
      "Ensure all tables involved in logical replication have an appropriate replica identity set. This can be done using:
    1. Default (Primary Key): `ALTER TABLE table_name REPLICA IDENTITY DEFAULT;`
    2. Unique Index: `ALTER TABLE table_name REPLICA IDENTITY USING INDEX index_name;`
    3. Full (All Columns): `ALTER TABLE table_name REPLICA IDENTITY FULL;`",
    )
  end

  return if config_hash.dig(:target_db_is_super_user)
  abort_with("User on target database does not have super user privilege")
end

.assert_wal_level_logical(db_config) ⇒ Object 



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# File 'lib/pg_easy_replicate.rb', line 261

def assert_wal_level_logical(db_config)
  db_config&.find do |r|
    r.dig(:name) == "wal_level" && r.dig(:setting) == "logical"
  end
end

.bootstrap(options) ⇒ Object 



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# File 'lib/pg_easy_replicate.rb', line 123

def bootstrap(options)
  logger.info("Setting up schema")
  setup_internal_schema

  if options[:copy_schema]
    logger.info("Setting up schema on target database")
    copy_schema(
      source_conn_string: source_db_url,
      target_conn_string: target_db_url,
    )
  end

  logger.info("Setting up replication user on source database")
  create_user(
    conn_string: source_db_url,
    special_user_role: options[:special_user_role],
    grant_permissions_on_schema: true,
  )

  logger.info("Setting up replication user on target database")
  create_user(
    conn_string: target_db_url,
    special_user_role: options[:special_user_role],
  )

  logger.info("Setting up groups tables")
  Group.setup
rescue => e
  abort_with("Unable to bootstrap: #{e.message}")
end

.cleanup(options) ⇒ Object 



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# File 'lib/pg_easy_replicate.rb', line 154

def cleanup(options)
  logger.info("Dropping groups table")
  Group.drop

  if options[:everything]
    logger.info("Dropping schema")
    drop_internal_schema
  end

  if options[:everything] || options[:sync]
    Orchestrate.drop_publication(
      group_name: options[:group_name],
      conn_string: source_db_url,
    )

    Orchestrate.drop_subscription(
      group_name: options[:group_name],
      target_conn_string: target_db_url,
    )
  end

  if options[:everything]
    # Drop users at last
    logger.info("Dropping replication user on source database")
    drop_user(conn_string: source_db_url)

    logger.info("Dropping replication user on target database")
    drop_user(conn_string: target_db_url)
  end
rescue => e
  abort_with("Unable to cleanup: #{e.message}")
end

.config(special_user_role: nil, copy_schema: false, tables: "", schema_name: nil) ⇒ Object 



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# File 'lib/pg_easy_replicate.rb', line 29

def config(
  special_user_role: nil,
  copy_schema: false,
  tables: "",
  schema_name: nil
)
  abort_with("SOURCE_DB_URL is missing") if source_db_url.nil?
  abort_with("TARGET_DB_URL is missing") if target_db_url.nil?

  system("which pg_dump")
  pg_dump_exists = $CHILD_STATUS.success?

  @config ||=
    begin
      q =
        "select name, setting from pg_settings where name in  ('max_wal_senders', 'max_worker_processes', 'wal_level',  'max_replication_slots', 'max_logical_replication_workers');"

      {
        source_db_is_super_user:
          is_super_user?(source_db_url, special_user_role),
        target_db_is_super_user:
          is_super_user?(target_db_url, special_user_role),
        source_db:
          Query.run(
            query: q,
            connection_url: source_db_url,
            user: db_user(source_db_url),
          ),
        target_db:
          Query.run(
            query: q,
            connection_url: target_db_url,
            user: db_user(target_db_url),
          ),
        pg_dump_exists: pg_dump_exists,
        tables_have_replica_identity:
          tables_have_replica_identity?(
            conn_string: source_db_url,
            tables: tables,
            schema_name: schema_name,
          ),
      }
    rescue => e
      abort_with("Unable to check config: #{e.message}")
    end
end

.copy_schema(source_conn_string:, target_conn_string:) ⇒ Object 



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# File 'lib/pg_easy_replicate.rb', line 227

def copy_schema(source_conn_string:, target_conn_string:)
  export_schema(conn_string: source_conn_string)
  import_schema(conn_string: target_conn_string)
end

.create_user(conn_string:, special_user_role: nil, grant_permissions_on_schema: false) ⇒ Object 



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# File 'lib/pg_easy_replicate.rb', line 297

def create_user(
  conn_string:,
  special_user_role: nil,
  grant_permissions_on_schema: false
)
  password = connection_info(conn_string)[:password].gsub("'") { "''" }

  drop_user(conn_string: conn_string)

  sql = <<~SQL
    create role #{quote_ident(internal_user_name)} with password '#{password}' login createdb createrole;
    grant all privileges on database #{quote_ident(db_name(conn_string))} TO #{quote_ident(internal_user_name)};
  SQL

  Query.run(
    query: sql,
    connection_url: conn_string,
    user: db_user(conn_string),
    transaction: false,
  )

  sql =
    if special_user_role
      "grant #{quote_ident(special_user_role)} to #{quote_ident(internal_user_name)};"
    else
      "alter user #{quote_ident(internal_user_name)} with superuser;"
    end

  Query.run(
    query: sql,
    connection_url: conn_string,
    user: db_user(conn_string),
    transaction: false,
  )

  return unless grant_permissions_on_schema
  Query.run(
    query:
      "grant all on schema #{quote_ident(internal_schema_name)} to #{quote_ident(internal_user_name)}",
    connection_url: conn_string,
    user: db_user(conn_string),
    transaction: false,
  )
rescue => e
  raise "Unable to create user: #{e.message}"
end

.drop_internal_schema ⇒ Object 



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# File 'lib/pg_easy_replicate.rb', line 187

def drop_internal_schema
  Query.run(
    query:
      "DROP SCHEMA IF EXISTS #{quote_ident(internal_schema_name)} CASCADE",
    connection_url: source_db_url,
    schema: internal_schema_name,
    user: db_user(source_db_url),
  )
rescue => e
  raise "Unable to drop schema: #{e.message}"
end

.drop_user(conn_string:, user: internal_user_name) ⇒ Object 



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# File 'lib/pg_easy_replicate.rb', line 344

def drop_user(conn_string:, user: internal_user_name)
  return unless user_exists?(conn_string: conn_string, user: user)

  sql = <<~SQL
   revoke all privileges on database #{quote_ident(db_name(conn_string))} from #{quote_ident(user)};
  SQL

  Query.run(
    query: sql,
    connection_url: conn_string,
    user: db_user(conn_string),
  )

  sql = <<~SQL
    drop role if exists #{quote_ident(user)};
  SQL

  Query.run(
    query: sql,
    connection_url: conn_string,
    user: db_user(conn_string),
  )
rescue => e
  raise "Unable to drop user: #{e.message}"
end

.export_schema(conn_string:) ⇒ Object 



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# File 'lib/pg_easy_replicate.rb', line 232

def export_schema(conn_string:)
  logger.info("Exporting schema to #{SCHEMA_FILE_LOCATION}")
  _, stderr, status =
    Open3.capture3(
      "pg_dump",
      conn_string,
      "-f",
      SCHEMA_FILE_LOCATION,
      "--schema-only",
    )

  success = status.success?
  raise stderr unless success
rescue => e
  raise "Unable to export schema: #{e.message}"
end

.import_schema(conn_string:) ⇒ Object 



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# File 'lib/pg_easy_replicate.rb', line 249

def import_schema(conn_string:)
  logger.info("Importing schema from #{SCHEMA_FILE_LOCATION}")

  _, stderr, status =
    Open3.capture3("psql", "-f", SCHEMA_FILE_LOCATION, conn_string)

  success = status.success?
  raise stderr unless success
rescue => e
  raise "Unable to import schema: #{e.message}"
end

.is_super_user?(url, special_user_role = nil) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/pg_easy_replicate.rb', line 267

def is_super_user?(url, special_user_role = nil)
  if special_user_role
    sql = <<~SQL
      SELECT r.rolname AS username,
        r1.rolname AS "role"
      FROM pg_catalog.pg_roles r
      LEFT JOIN pg_catalog.pg_auth_members m ON (m.member = r.oid)
      LEFT JOIN pg_roles r1 ON (m.roleid=r1.oid)
      WHERE r.rolname = '#{db_user(url)}'
      ORDER BY 1;
    SQL

    r = Query.run(query: sql, connection_url: url, user: db_user(url))
    # If special_user_role is passed just ensure the url in conn_string has been granted
    # the special_user_role
    r.any? { |q| q[:role] == special_user_role }
  else
    r =
      Query.run(
        query:
          "SELECT rolname, rolsuper FROM pg_roles where rolname = '#{db_user(url)}';",
        connection_url: url,
        user: db_user(url),
      )
    r.any? { |q| q[:rolsuper] }
  end
rescue => e
  raise "Unable to check superuser conditions: #{e.message}"
end

.logger ⇒ Object 



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# File 'lib/pg_easy_replicate.rb', line 216

def logger
  @logger ||=
    begin
      logger = Ougai::Logger.new($stdout)
      logger.level =
        ENV["DEBUG"] ? Ougai::Logger::TRACE : Ougai::Logger::INFO
      logger.with_fields = { version: PgEasyReplicate::VERSION }
      logger
    end
end

.setup_internal_schema ⇒ Object 



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# File 'lib/pg_easy_replicate.rb', line 199

def setup_internal_schema
  sql = <<~SQL
    create schema if not exists #{quote_ident(internal_schema_name)};
    grant usage on schema #{quote_ident(internal_schema_name)} to #{quote_ident(db_user(source_db_url))};
    grant create on schema #{quote_ident(internal_schema_name)} to #{quote_ident(db_user(source_db_url))};
  SQL

  Query.run(
    query: sql,
    connection_url: source_db_url,
    schema: internal_schema_name,
    user: db_user(source_db_url),
  )
rescue => e
  raise "Unable to setup schema: #{e.message}"
end

.tables_have_replica_identity?(conn_string:, tables: "", schema_name: nil) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/pg_easy_replicate.rb', line 390

def tables_have_replica_identity?(
  conn_string:,
  tables: "",
  schema_name: nil
)
  schema_name ||= "public"

  table_list =
    determine_tables(
      schema: schema_name,
      conn_string: source_db_url,
      list: tables,
    )
  return false if table_list.empty?

  formatted_table_list = table_list.map { |table| "'#{table}'" }.join(", ")

  sql = <<~SQL
    SELECT t.relname AS table_name,
          CASE
            WHEN t.relreplident = 'd' THEN 'default'
            WHEN t.relreplident = 'n' THEN 'nothing'
            WHEN t.relreplident = 'i' THEN 'index'
            WHEN t.relreplident = 'f' THEN 'full'
          END AS replica_identity
    FROM pg_class t
    JOIN pg_namespace ns ON t.relnamespace = ns.oid
    WHERE ns.nspname = '#{schema_name}'
      AND t.relkind = 'r'
      AND t.relname IN (#{formatted_table_list})
  SQL

  results =
    Query.run(
      query: sql,
      connection_url: conn_string,
      user: db_user(conn_string),
    )

  results.all? { |r| r[:replica_identity] != "nothing" }
end

.user_exists?(conn_string:, user: internal_user_name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/pg_easy_replicate.rb', line 370

def user_exists?(conn_string:, user: internal_user_name)
  sql = <<~SQL
    SELECT r.rolname AS username,
      r1.rolname AS "role"
    FROM pg_catalog.pg_roles r
    LEFT JOIN pg_catalog.pg_auth_members m ON (m.member = r.oid)
    LEFT JOIN pg_roles r1 ON (m.roleid=r1.oid)
    WHERE r.rolname = '#{user}'
    ORDER BY 1;
  SQL

  Query
    .run(
      query: sql,
      connection_url: conn_string,
      user: db_user(conn_string),
    )
    .any? { |q| q[:username] == user }
end