Usage

Command line reference

chameleon command [ [ --config ] [ --source ] [ --schema ]  [ --tables ] [--logid] [ --debug ] [ --rollbar-level ] ] [ --version ] [ --full ]

Options

Option	Description	Default	Example
--config	Specifies the configuration to use in ~.pg_chameleon/configuration/. The configuration name should be the file without the extension .yml	default	--config foo will use the file ~.pg_chameleon/configuration/foo.yml
--source	Specifies the source within a configuration file.	N/A	--source bar
--schema	Specifies a schema configured within a source.	N/A	--schema schema_foo
--tables	Specifies one or more tables configured in a schema. Multiple tables can be specified separated by comma. The table must have the schema.	N/A	--tables schema_foo.table_bar
--logid	Specifies the log id entry for displaying the error details	N/A	--logid 30
--debug	When added to the command line the debug option disables any daemonisation and outputs all the logging to the console. The keybord interrupt signal is trapped correctly.	N/A	--debug
--version	Displays the package version.	N/A	--version
--rollbar-level	Sets the maximum level for the messages to be sent to rolllbar. Accepted values: “critical” “error” “warning” “info”	info	--rollbar-level error
--full	Runs a VACUUM FULL on the log tables when the run_maintenance is executed	N/A	--full

Command list reference

Command	Description	Options
set_configuration_files	Setup the example configuration files and directories in ~/.pg_chameleon
show_config	Displays the configuration for the configuration	--config
show_sources	Displays the sourcches configured for the configuration	--config
show_status	Displays an overview of the status of the sources configured within the configuration. Specifying the source gives more details about that source	--config --source
show_errors	Displays the errors logged by the replay function. If a log id is specified then the log entry is displayed entirely	--config --logid
create_replica_schema	Creates a new replication schema into the config’s destination database	--config
drop_replica_schema	Drops an existing replication schema from the config’s destination database	--config
upgrade_replica_schema	Upgrades the replica schema from a an older version	--config
add_source	Adds a new source to the replica catalogue	--config --source
drop_source	Remove an existing source from the replica catalogue	--config --source
init_replica	Initialise the replica for an existing source	--config --source
copy_schema	Copy only the schema from mysql to PostgreSQL.	--config --source
update_schema_mappings	Update the schema mappings stored in the replica catalogue using the data from the configuration file.	--config --source
refresh_schema	Synchronise all the tables for a given schema within an already initialised source.	--config --source --schema
sync_tables	Synchronise one or more tables within an already initialised source. The switch --tables accepts the special name disabled to resync all the tables with replica disabled.	--config --source --tables
start_replica	Starts the replica process daemon	--config --source
stop_replica	Stops the replica process daemon	--config --source
detach_replica	Detaches a replica from the mysql master configuring the postgres schemas to work as a standalone system. Useful for migrations.	--config --source
enable_replica	Enables the replica for the given source changing the source status to stopped. It’s useful if the replica crashes.	--config --source
run_maintenance	Runs a VACUUM on the log tables for the given source. If is specified then the maintenance runs a VACUUM FULL	--config --source --full
stop_all_replicas	Stops all the running sources within the target postgresql database.	--config

Example

Create a virtualenv and activate it

python3 -m venv venv
source venv/bin/activate

Install pg_chameleon

pip install pip --upgrade
pip install pg_chameleon

Run the set_configuration_files command in order to create the configuration directory.

chameleon set_configuration_files

cd in ~/.pg_chameleon/configuration and copy the file config-example.yml` to ``default.yml.

In MySQL create a user for the replica.

CREATE USER usr_replica ;
SET PASSWORD FOR usr_replica=PASSWORD('replica');
GRANT ALL ON sakila.* TO 'usr_replica';
GRANT RELOAD ON *.* to 'usr_replica';
GRANT REPLICATION CLIENT ON *.* to 'usr_replica';
GRANT REPLICATION SLAVE ON *.* to 'usr_replica';
FLUSH PRIVILEGES;

Add the configuration for the replica to my.cnf. It requires a MySQL restart.

binlog_format= ROW
binlog_row_image=FULL
log-bin = mysql-bin
server-id = 1
expire_logs_days = 10

In PostgreSQL create a user for the replica and a database owned by the user

CREATE USER usr_replica WITH PASSWORD 'replica';
CREATE DATABASE db_replica WITH OWNER usr_replica;

Check you can connect to both databases from the machine where pg_chameleon is installed.

For MySQL

mysql -p -h derpy -u usr_replica sakila
Enter password:
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 116
Server version: 5.6.30-log Source distribution

Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql>

For PostgreSQL

psql  -h derpy -U usr_replica db_replica
Password for user usr_replica:
psql (9.5.5)
Type "help" for help.
db_replica=>

Check the docs for the configuration file reference. It will help you to configure correctly the connections.

Initialise the replica

chameleon create_replica_schema --debug
chameleon add_source --config default  --debug
chameleon init_replica --config default --debug

Start the replica with

chameleon start_replica --config default --source example

Check the source status

chameleon show_status --source example

Check the error log

chameleon show_errors

chameleon start_replica --config default --source example

To stop the replica

chameleon stop_replica --config default --source example

To detach the replica

chameleon detach_replica --config default --source example