使用jq筛选出元素的特定json数组字段。

Question

我运行了一个aws rds describe-instances，得到了一个实例的json数组，大致如下所示：

"DBInstances": [
        {
            "DBInstanceIdentifier": "my-rds",
            "Endpoint": {
                "HostedZoneId": "XXXXXXXXXXXX"
            },
            "DBSecurityGroups": [],
            "VpcSecurityGroups": [
                {
                    "VpcSecurityGroupId": "sg-12345",
                    "Status": "active"
                },
                {
                    "VpcSecurityGroupId": "sg-12345",
                    "Status": "active"
                }
            ],
            "DBParameterGroups": [
                {
                    "DBParameterGroupName": "postgres-12",
                    "ParameterApplyStatus": "in-sync"
                }
            ],
            "AvailabilityZone": "us-west-1c",
            "DBSubnetGroup": {
                "VpcId": "vpc-123456",
                "SubnetGroupStatus": "Complete",
                "Subnets": [
                    {
                        "SubnetIdentifier": "subnet-123456",
                        "SubnetAvailabilityZone": {
                            "Name": "us-west-1b"
                        },
                        "SubnetOutpost": {},
                        "SubnetStatus": "Active"
                    },
                    {
                        "SubnetIdentifier": "subnet-12345",
                        "SubnetAvailabilityZone": {
                            "Name": "us-west-1c"
                        },
                        "SubnetOutpost": {},
                        "SubnetStatus": "Active"
                    },
                    {
                        "SubnetIdentifier": "subnet-12345",
                        "SubnetAvailabilityZone": {
                            "Name": "us-west-1e"
                        },
                        "SubnetOutpost": {},
                        "SubnetStatus": "Active"
                    }
                ]
            },
            "EngineVersion": "11.9",
            "AutoMinorVersionUpgrade": true,
            "ReadReplicaDBInstanceIdentifiers": [],
            "LicenseModel": "foobar",
            "OptionGroupMemberships": [
                {
                    "OptionGroupName": "randomname",
                    "Status": "in-sync"
                }
            ],
        },
    }

输出明显截断。

有没有一种使用(可能是jq)的方法？印刷：

( a) DBInstances数组的所有元素

对于每个元素，只打印

( b) DBInstanceIdentifier和EngineVersion

Answer 1

您可以使用以下JQ过滤器：

.DBInstances[] | [ .DBInstanceIdentifier, .EngineVersion ]

哪里

• .DBInstances[]遍历DBInstances数组
• [ .DBInstanceIdentifier, .EngineVersion ]创建一个只包含DBInstanceIdentifier和EngineVersion键的数组。

jq '.DBInstances[] | [ .DBInstanceIdentifier, .EngineVersion ]'

JqPlay演示

对于当前的JSON示例( DBInstances数组中只有1项)，结果是：

[
  "my-rds",
  "11.9"
]

Answer 2

不是用.jq解决的，而是使用aws cli特性解决的：

aws rds describe-db-instances --query 'DBInstances[*].[DBInstanceIdentifier, EngineVersion]'