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Arseny Zinchenko
Arseny Zinchenko

Posted on • Originally published at rtfm.co.ua on

AWS: RDS logs, export to the CloudWatch Logs and CloudFormation template

#aws #amazonwebservices #cloudformation #cloudwatch

We have a bunch of the AWS RDS with MariaDB.

Backend-developers asked me to enable Slow requests logs so they can debug their application.

So the task is: enable AWS RDS logging and configure export to the CloudWatch Logs for further analysis.

As everything else – our RDS instances are configured via CloudFormation templates, so will add some examples as well.

Beside standard general/error/slow logs – there is also Audit Plugin for MariaDB to enable Audit-log, but this is topic for another post. You can check its documentation here>>>.

DB Parameter Groups – enabling logs

Currently, our Parameter Group looks like next:

...
    "MasterDBParamGroup": {
      "Type": "AWS::RDS::DBParameterGroup",
      "Properties": {
        "Description": "Master Database Parameter Group",
        "Family": "mariadb10.0",
        "Parameters" : {
          "net_read_timeout": 60
        },
        "Tags" : [
          {"Key" : "Name", "Value" : { "Fn::Join" : [ "-", [ {"Ref" : "AWS::StackName"}, "master-db-params"] ] } },
          {"Key" : "Env", "Value" : {"Ref" : "ENV"} }
        ]
      }
    },
...
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RDS has four logs types:

  • audit
  • error
  • general
  • slowquery

To enable them need to update such parameters:

  • slow_query_log
  • general_log
  • log_error (enabled by default)

Also good to update those:

  • long_query_time – time in seconds after which a request will be logged to the Slow log
  • log_output – set to FILE to enable export to the CloudWatch Logs

At first – let’s do it via AWS UI, and then will update a CloudFormation template.

Find an instance’s Parameter Group:

Add the necessary options:

Check them:

$ aws rds --profile bm-backend describe-db-parameters --db-parameter-group-name mobilebackend-dev-masterdbparamgroup-258i35vgxvdi | grep -A1 'slow_query_log\|general_log\|log_error'

"ParameterName": "general_log",
"ParameterValue": "1",

--

"ParameterName": "general_log_file",
"ParameterValue": "/rdsdbdata/log/general/mysql-general.log",

--

"ParameterName": "log_error",
"ParameterValue": "/rdsdbdata/log/error/mysql-error.log",

--

"ParameterName": "slow_query_log",
"ParameterValue": "1",

--

"ParameterName": "slow_query_log_file",
"ParameterValue": "/rdsdbdata/log/slowquery/mysql-slowquery.log",
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Logs have to appear in the Logs & events.

Also – do not forget to set log_output to the FILE type (default value is TABLE):

Save changes.

CloudWatch Logs export

Go to an RDS instance and click Modify:

List to the bottom and chose logs to be exported to the CloudWatch:

Press Continue, check the list of settings to be updated, click Modify DB instance:

Wait a couple of minutes:

Go to the CloudWatch Logs – and voila:

Logs data:

CloudFormation template

The last thing is to update our CloudFormation template to apply changes to all servers.

Here we need to update the AWS::RDS::DBParameterGroup resource and add the following parameters:

...
    "MasterDBParamGroup": {
      "Type": "AWS::RDS::DBParameterGroup",
      "Properties": {
        "Description": "Master Database Parameter Group",
        "Family": "mariadb10.0",
        "Parameters" : {
          "log_output": "FILE",
          "general_log": 1,
          "slow_query_log": 1,
          "long_query_time": 10,
          "log_queries_not_using_indexes": 1,
          "net_read_timeout": 60
        },
        "Tags" : [
          {"Key" : "Name", "Value" : { "Fn::Join" : [ "-", [ {"Ref" : "AWS::StackName"}, "master-db-params"] ] } },
          {"Key" : "Env", "Value" : {"Ref" : "ENV"} }
        ]
      }
    },
...
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Next – enable the Export: update the AWS::RDS::DBInstance resource and add the EnableCloudwatchLogsExports with logs list to be exported – error, general, slowquery:

...
    "DB1MasterRDS" : {
      "Type" : "AWS::RDS::DBInstance",
      "Properties" : {
        "DBInstanceIdentifier" : { "Fn::Join" : [ "-", [ {"Ref" : "AWS::StackName"}, "db1-master-rds"] ] },
        "MasterUsername" : { "Ref" : "DB1RootUser" },
        "MasterUserPassword" : { "Ref" : "DB1RootPassword" },
        "AllocatedStorage" : { "Ref" : "DB1AllocatedStorage" },
        "Engine" : "mariadb",
        "StorageType": "gp2",
        "AutoMinorVersionUpgrade": false,
        "PubliclyAccessible" : false,
        "DBInstanceClass" : { "Ref" : "DB1MasterDBInstanceClass" },
        "DBSubnetGroupName" : { "Ref" : "DB1SubnetGroup" },
        "DBParameterGroupName" : {"Ref" : "MasterDBParamGroup" },
        "EnableCloudwatchLogsExports": [
              "error",
              "general",
              "slowquery"
            ],
        "BackupRetentionPeriod": {"Ref" : "BackupRetentionPeriod" },
        "PreferredBackupWindow": {"Ref" : "PreferredBackupWindow" },
        "VPCSecurityGroups" : [ { "Fn::GetAtt" : [ "MasterDBSecurityGroup", "GroupId" ] } ],
        "MultiAZ": {"Ref" : "MultiAZ" },
        "Tags" : [
          {"Key" : "Name", "Value" : { "Fn::Join" : [ "-", [ {"Ref" : "AWS::StackName"}, "db1-master-rds"] ] } },
          {"Key" : "Env", "Value" : {"Ref" : "ENV"} }
        ]
      },
      "DeletionPolicy" : "Snapshot"
    },
...
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Run a stack update:

Check log groups:

Done.

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