Getting started with Orchestrator

Orchestrator is a MySQL high availability and replication management tool. In this blog post, we will cover the first steps for getting started with it on an existing topology.

The code examples assume you are running Centos 7, but the general steps should be similar if you are running other operating system versions/flavors.

Prep work

1. Create a MySQL user on each of your database servers.
Orchestrator will connect with this user to discover the topology and to perform any changes you tell it to make.

CREATE USER 'orchestrator'@'%' IDENTIFIED BY '****';
GRANT SUPER, PROCESS, REPLICATION SLAVE, RELOAD ON *.* TO 'orchestrator'@'%';
GRANT SELECT ON mysql.slave_master_info TO 'orchestrator'@'%';
GRANT SELECT ON meta.* TO 'orchestrator'@'%';

Note: Orchestrator reads replication credentials stored in mysql.slave_master_info table, which implies you need to set up your servers with master_info_repository = ‘TABLE’ option if you want Orchestrator to be able to make topology changes on your behalf.

2. (Optional) Create a table to store the cluster name on each of your database servers.
The idea is that if you set this up on each of your database servers, Orchestrator will pick up the cluster name automatically. While you could skip this step and just rename the clusters via the GUI later, it is a nice to have.

CREATE DATABASE meta;

CREATE TABLE meta.cluster (
  anchor TINYINT NOT NULL,
  cluster_name VARCHAR(128) CHARSET ascii NOT NULL DEFAULT '',
  cluster_domain VARCHAR(128) CHARSET ascii NOT NULL DEFAULT '',
  PRIMARY KEY (anchor)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO meta.cluster (anchor, cluster_name, cluster_domain) VALUES (1, 'testcluster', 'example.com');

Installation steps

1. Get the prerequisites.
Orchestrator client requires jq package, which is available from epel repo, so let’s install that first:

sudo yum install epel-release
sudo yum install jq

2. Install Orchestrator.
Orchestrator is readily available as .deb or .rpm package so let’s use that:

sudo yum install https://github.com/github/orchestrator/releases/download/v3.0.11/orchestrator-3.0.11-1.x86_64.rpm

3. Prepare the configuration file.
Let’s start by copying the sample config file:

cp /usr/local/orchestrator/orchestrator-sample.conf.json /etc/orchestrator.conf.json

There are a lot of settings we can tweak, but to get started, we need to config the following values:

  • “MySQLTopologyUser”
  • “MySQLTopologyPassword”

These are the ones we defined above.

  • “DetectClusterAliasQuery”

We have to define a query that will let Orchestrator figure out the cluster name based on the table we created in the previous step.

  • “BackendDB”
  • “SQLite3DataFile”

You can use different backends for Orchestrator metadata. For simplicity, I suggest using SQLite which requires only the two lines above.

Here’s a complete configuration file:

{
  "Debug": true,
  "EnableSyslog": false,
  "ListenAddress": ":3000",
  "MySQLTopologyUser": "orchestrator",
  "MySQLTopologyPassword": "****",
  "MySQLTopologyCredentialsConfigFile": "",
  "MySQLTopologySSLPrivateKeyFile": "",
  "MySQLTopologySSLCertFile": "",
  "MySQLTopologySSLCAFile": "",
  "MySQLTopologySSLSkipVerify": true,
  "MySQLTopologyUseMutualTLS": false,
  "MySQLOrchestratorHost": "127.0.0.1",
  "MySQLOrchestratorPort": 3306,
  "MySQLOrchestratorDatabase": "orchestrator",
  "MySQLOrchestratorUser": "orc_server_user",
  "MySQLOrchestratorPassword": "orc_server_password",
  "MySQLOrchestratorCredentialsConfigFile": "",
  "MySQLOrchestratorSSLPrivateKeyFile": "",
  "MySQLOrchestratorSSLCertFile": "",
  "MySQLOrchestratorSSLCAFile": "",
  "MySQLOrchestratorSSLSkipVerify": true,
  "MySQLOrchestratorUseMutualTLS": false,
  "MySQLConnectTimeoutSeconds": 1,
  "DefaultInstancePort": 3306,
  "DiscoverByShowSlaveHosts": true,
  "InstancePollSeconds": 5,
  "UnseenInstanceForgetHours": 240,
  "SnapshotTopologiesIntervalHours": 0,
  "InstanceBulkOperationsWaitTimeoutSeconds": 10,
  "HostnameResolveMethod": "default",
  "MySQLHostnameResolveMethod": "@@hostname",
  "SkipBinlogServerUnresolveCheck": true,
  "ExpiryHostnameResolvesMinutes": 60,
  "RejectHostnameResolvePattern": "",
  "ReasonableReplicationLagSeconds": 10,
  "ProblemIgnoreHostnameFilters": [],
  "VerifyReplicationFilters": false,
  "ReasonableMaintenanceReplicationLagSeconds": 20,
  "CandidateInstanceExpireMinutes": 60,
  "AuditLogFile": "",
  "AuditToSyslog": false,
  "RemoveTextFromHostnameDisplay": ".mydomain.com:3306",
  "ReadOnly": false,
  "AuthenticationMethod": "",
  "HTTPAuthUser": "",
  "HTTPAuthPassword": "",
  "AuthUserHeader": "",
  "PowerAuthUsers": [
    "*"
  ],
  "ClusterNameToAlias": {
    "127.0.0.1": "test suite"
  },
  "SlaveLagQuery": "",
  "DetectClusterAliasQuery": "SELECT ifnull(max(cluster_name), '''') as cluster_alias from meta.cluster where anchor=1;",
  "DetectClusterDomainQuery": "",
  "DetectInstanceAliasQuery": "",
  "DetectPromotionRuleQuery": "",
  "DataCenterPattern": "[.]([^.]+)[.][^.]+[.]mydomain[.]com",
  "PhysicalEnvironmentPattern": "[.]([^.]+[.][^.]+)[.]mydomain[.]com",
  "PromotionIgnoreHostnameFilters": [],
  "DetectSemiSyncEnforcedQuery": "",
  "ServeAgentsHttp": false,
  "AgentsServerPort": ":3001",
  "AgentsUseSSL": false,
  "AgentsUseMutualTLS": false,
  "AgentSSLSkipVerify": false,
  "AgentSSLPrivateKeyFile": "",
  "AgentSSLCertFile": "",
  "AgentSSLCAFile": "",
  "AgentSSLValidOUs": [],
  "UseSSL": false,
  "UseMutualTLS": false,
  "SSLSkipVerify": false,
  "SSLPrivateKeyFile": "",
  "SSLCertFile": "",
  "SSLCAFile": "",
  "SSLValidOUs": [],
  "URLPrefix": "",
  "StatusEndpoint": "/api/status",
  "StatusSimpleHealth": true,
  "StatusOUVerify": false,
  "AgentPollMinutes": 60,
  "UnseenAgentForgetHours": 6,
  "StaleSeedFailMinutes": 60,
  "SeedAcceptableBytesDiff": 8192,
  "PseudoGTIDPattern": "",
  "PseudoGTIDPatternIsFixedSubstring": false,
  "PseudoGTIDMonotonicHint": "asc:",
  "DetectPseudoGTIDQuery": "",
  "BinlogEventsChunkSize": 10000,
  "SkipBinlogEventsContaining": [],
  "ReduceReplicationAnalysisCount": true,
  "FailureDetectionPeriodBlockMinutes": 60,
  "RecoveryPollSeconds": 10,
  "RecoveryPeriodBlockSeconds": 3600,
  "RecoveryIgnoreHostnameFilters": [],
  "RecoverMasterClusterFilters": [
    ".*"
  ],
  "RecoverIntermediateMasterClusterFilters": [
    "_intermediate_master_pattern_"
  ],
  "OnFailureDetectionProcesses": [
    "echo 'Detected {failureType} on {failureCluster}. Affected replicas: {countSlaves}' >> /tmp/recovery.log"
  ],
  "PreFailoverProcesses": [
    "echo 'Will recover from {failureType} on {failureCluster}' >> /tmp/recovery.log"
  ],
  "PostFailoverProcesses": [
    "echo '(for all types) Recovered from {failureType} on {failureCluster}. Failed: {failedHost}:{failedPort}; Successor: {successorHost}:{successorPort}' >> /tmp/recovery.log"
  ],
  "PostUnsuccessfulFailoverProcesses": [],
  "PostMasterFailoverProcesses": [
    "echo 'Recovered from {failureType} on {failureCluster}. Failed: {failedHost}:{failedPort}; Promoted: {successorHost}:{successorPort}' >> /tmp/recovery.log"
  ],
  "PostIntermediateMasterFailoverProcesses": [
    "echo 'Recovered from {failureType} on {failureCluster}. Failed: {failedHost}:{failedPort}; Successor: {successorHost}:{successorPort}' >> /tmp/recovery.log"
  ],
  "CoMasterRecoveryMustPromoteOtherCoMaster": true,
  "DetachLostSlavesAfterMasterFailover": true,
  "ApplyMySQLPromotionAfterMasterFailover": true,
  "MasterFailoverDetachSlaveMasterHost": false,
  "MasterFailoverLostInstancesDowntimeMinutes": 0,
  "PostponeSlaveRecoveryOnLagMinutes": 0,
  "OSCIgnoreHostnameFilters": [],
  "GraphiteAddr": "",
  "GraphitePath": "",
  "GraphiteConvertHostnameDotsToUnderscores": true,
  "BackendDB": "sqlite",
  "SQLite3DataFile": "/usr/local/orchestrator/orchestrator.db"
}

4. Prepare systemd script.
At the time of this writing, a systemd script to manage start/stop of the service is not included. I set that up as follows:

vi /etc/systemd/system/orchestrator.service
[Unit]
Description="orchestrator: MySQL replication management and visualization"
After=syslog.target network.target

[Service]
Type=simple
ExecStart=/usr/local/orchestrator/orchestrator --verbose http
PIDFile=/var/run/orchestrator.pid
WorkingDirectory=/usr/local/orchestrator

[Install]
WantedBy=multi-user.target

5. Reload the service so it reads the updated configuration file /etc/orchestrator.conf.json.

service orchestrator reload

That’s it for the installation steps.

Using the GUI

The first step is pointing Orchestrator to a starting host. It will then automatically discover any other hosts that are members of the same cluster by crawling up and down the replication chain.

1. Using a browser, open the GUI (by default port 3000) on the host where you installed Orchestrator:
http://192.168.56.100:3000/

2. Click ‘Discover‘ on the top bar, enter the ip address and port of any host you want, and hit the Submit button.

3. Click on Clusters -> Dashboard. After a few seconds, you should see the cluster being shown (refresh the page if needed).

4. Now click on the cluster name and you should see the details about all current members of the replication topology.

The cluster should have automatically been named according to what is specified in meta.cluster table.
You can also use the GUI to drag & drop to perform topology changes, provided you are using GTID or pseudo-GTID (which is a topic for a different post).

Closing thoughts

Orchestrator is rapidly becoming the go-to topology management tool in the MySQL world. I encourage you to start playing with it as soon as possible.

If you are interested in learning more, I suggest you also check out the following posts in the Pythian blog.

Happy Orchestrating!

MySQL High availability with HAProxy, Consul and Orchestrator

Graceful master switchover with ProxySQL and Orchestrator

 

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