getLog（数据库命令）

定义

getLog

getLog is an administrative command that returns the most recent 1024 logged events for a mongod or mongos instance. getLog does not read log data from the log file. Instead, it reads data from a RAM cache of logged events from either mongod or mongos. To run getLog, use the db.adminCommand() method.

getLog returns log data in escaped Relaxed Extended JSON v2.0 format. Previously, log data was returned as plaintext.

兼容性

此命令可用于以下环境中托管的部署：

MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud

注意

This command is supported in all MongoDB Atlas clusters. For information on Atlas support for all commands, see Unsupported Commands.

MongoDB Enterprise：基于订阅、自我管理的 MongoDB 版本
MongoDB Community：源代码可用、免费使用且可自行管理的 MongoDB 版本

语法

该命令具有以下语法：

db.adminCommand(
   {
     getLog: <value>
   }
)

命令字段

The possible values for getLog are:

值	说明
`*`	Returns a list of the available values to the `getLog` command.
`global`	返回所有最近日志条目的组合输出。
`startupWarnings`	返回日志条目，其中可能包含当前进程启动时 MongoDB日志中的错误或警告。如果进程启动时没有出现警告，则此过滤可能会返回一个空大量。

注意

The getLog command no longer accepts the rs value, as this categorization of message type has been deprecated. Instead, log messages are now always identified by their component - including REPL for replication messages. See Filtering by Component for log parsing examples that filter on the component field.

输出

如果指定*，则命令返回一个包含其他可接受值名称的文档。

否则，该命令会返回包含以下字段的文档：

totalLinesWritten 字段，包含日志事件数
log 字段，包含日志事件数组
包含状态和时间戳信息的 db.adminCommand() 响应文档。

行为

行截断

getLog 截断任何包含超过 1024 个字符的事件。

转义字符

getLog returns log data in escaped Relaxed Extended JSON v2.0 format, using the following escape sequences to render log output as valid JSON:

所代表的字符	转义序列
引号 (`"`)	`\"`
Backslash (`\`)	`\\`
退格 (`0x08`)	`\b`
进纸 (`0x0C`)	`\f`
换行符 (`0x0A`)	`\n`
回车 (`0x0D`)	`\r`
Horizontal tab (`0x09`)	`\t`

上面未列出的控制字符使用 \uXXXX 进行转义，其中 "XXXX" 是十六进制的 unicode 代码点。具有无效 UTF-8 编码的字节将替换为 \ufffd 表示的 unicode 替换字符。

过滤

在 `mongosh`

getLog 输出可以进行过滤，以使结果更具可读性或与特定条件相匹配。

以下操作仅打印 log 字段（其中包含所有最近日志事件的数组），并删除每条日志消息中的字符转义：

db.adminCommand( { getLog:'global'} ).log.forEach(x => {print(x)})

This operation presents getLog output in the same format as the MongoDB log file.

注意

getLog only shows the most recent 1024 logged events, and is not a replacement for the MongoDB log file.

外部 `mongosh` 和 `jq`

在使用 MongoDB 结构化日志时，您可以使用第三方 jq 命令行实用程序轻松美观地打印日志条目，并提供强大的基于键的匹配和过滤功能。

jq 是一个开源 JSON 解析器，用于 Linux、Windows 和 macOS。

To use jq with getLog output, you must use the --eval option to mongosh. The following operation uses jq to filter on the REPL component to present only those log messages associated with replication:

mongosh --quiet --eval "db.adminCommand( { getLog:'global'} ).log.forEach(x => {print(x)})" | jq -c '. | select(.c=="REPL")'

Be sure to provide any necessary connection-specific parameters to mongosh as needed, such as --host or --port.

See Parsing Structured Log Messages for more examples of filtering log output using jq. The jq syntax presented in each linked example can be used with the above mongo --eval operation with minor adjustment. For example, the following syntax adapts the linked "Counting Unique Messages" example for use with getLog:

mongosh --quiet --eval "db.adminCommand( { getLog:'global'} ).log.forEach(x => {print(x)})" | jq -r ".msg" | sort | uniq -c | sort -rn | head -10

示例

检索可用的日志过滤器

The following operation, run from mongosh, returns the available log filters for passing to getLog:

db.adminCommand( { getLog: "*" } )

该操作将返回以下文档：

{ "names" : [ "global", "startupWarnings" ], "ok" : 1 }

从日志中检索最近发生的事件

The following operation, run from mongosh, retrieves the most recent global events for a mongod or mongos instance:

db.adminCommand( { getLog : "global" } )

该操作返回类似于以下内容的文档：

{
      "totalLinesWritten" : <num>,
      "log" : [
              "{\"t\":{\"$date\":\"2020-05-19T19:10:48.871+00:00\"},\"s\":\"I\",  \"c\":\"STORAGE\",  \"id\":4615611, \"ctx\":\"initandlisten\",\"msg\":\"MongoDB starting\",\"attr\":{\"pid\":12345,\"port\":27001,\"dbPath\":\"/var/lib/mongo\",\"architecture\":\"64-bit\",\"host\":\"server1.example.com\"}}",
              "{\"t\":{\"$date\":\"2020-05-19T19:10:48.871+00:00\"},\"s\":\"I\",  \"c\":\"CONTROL\",  \"id\":23403,   \"ctx\":\"initandlisten\",\"msg\":\"Build Info\",\"attr\":{\"buildInfo\":{\"version\":\"4.4.0\",\"gitVersion\":\"328c35e4b883540675fb4b626c53a08f74e43cf0\",\"openSSLVersion\":\"OpenSSL 1.1.1c FIPS  28 May 2019\",\"modules\":[],\"allocator\":\"tcmalloc\",\"environment\":{\"distmod\":\"rhel80\",\"distarch\":\"x86_64\",\"target_arch\":\"x86_64\"}}}}",
              "{\"t\":{\"$date\":\"2020-05-19T19:10:48.871+00:00\"},\"s\":\"I\",  \"c\":\"CONTROL\",  \"id\":51765,   \"ctx\":\"initandlisten\",\"msg\":\"Operating System\",\"attr\":{\"os\":{\"name\":\"CentOS Linux release 8.0.1905 (Core) \",\"version\":\"Kernel 4.18.0-80.11.2.el8_0.x86_64\"}}}",
              "{\"t\":{\"$date\":\"2020-05-19T19:10:48.871+00:00\"},\"s\":\"I\",  \"c\":\"CONTROL\",  \"id\":21951,   \"ctx\":\"initandlisten\",\"msg\":\"Options set by command line\",\"attr\":{\"options\":{\"config\":\"/etc/mongod.conf\",\"net\":{\"bindIp\":\"127.0.0.1\",\"port\":27001},\"processManagement\":{\"fork\":true,\"timeZoneInfo\":\"/usr/share/zoneinfo\"},\"replication\":{\"replSetName\":\"repl-shard1\"},\"sharding\":{\"clusterRole\":\"shardsvr\"},\"storage\":{\"dbPath\":\"/var/lib/mongo\",\"journal\":{\"enabled\":true},\"wiredTiger\":{\"engineConfig\":{\"cacheSizeGB\":0.1}}},\"systemLog\":{\"destination\":\"file\",\"logAppend\":true,\"path\":\"/var/log/mongodb/mongod.log\"}}}}",
              "{\"t\":{\"$date\":\"2020-05-19T19:10:48.873+00:00\"},\"s\":\"I\",  \"c\":\"STORAGE\",  \"id\":22270,   \"ctx\":\"initandlisten\",\"msg\":\"Storage engine to use detected by data files\",\"attr\":{\"dbpath\":\"/var/lib/mongo\",\"storageEngine\":\"wiredTiger\"}}",
              "{\"t\":{\"$date\":\"2020-05-19T19:10:48.873+00:00\"},\"s\":\"I\",  \"c\":\"STORAGE\",  \"id\":22315,   \"ctx\":\"initandlisten\",\"msg\":\"wiredtiger_open config\",\"attr\":{\"config\":\"create,cache_size=102M,session_max=33000,eviction=(threads_min=4,threads_max=4),config_base=false,statistics=(fast),log=(enabled=true,archive=true,path=journal,compressor=snappy),file_manager=(close_idle_time=100000,close_scan_interval=10,close_handle_minimum=250),statistics_log=(wait=0),verbose=[recovery_progress,checkpoint_progress,compact_progress],\"}}",
              "{\"t\":{\"$date\":\"2020-05-19T19:10:58.877+00:00\"},\"s\":\"I\",  \"c\":\"CONNPOOL\", \"id\":22576,   \"ctx\":\"ReplicaSetMonitor-TaskExecutor\",\"msg\":\"Connecting\",\"attr\":{\"hostAndPort\":\"server1.example.com:27001\"}}",
              "{\"t\":{\"$date\":\"2020-05-19T19:10:58.877+00:00\"},\"s\":\"I\",  \"c\":\"CONNPOOL\", \"id\":22576,   \"ctx\":\"ReplicaSetMonitor-TaskExecutor\",\"msg\":\"Connecting\",\"attr\":{\"hostAndPort\":\"server2.example.com:27001\"}}",
              "{\"t\":{\"$date\":\"2020-05-19T19:10:58.877+00:00\"},\"s\":\"I\",  \"c\":\"CONNPOOL\", \"id\":22576,   \"ctx\":\"ReplicaSetMonitor-TaskExecutor\",\"msg\":\"Connecting\",\"attr\":{\"hostAndPort\":\"server3.example.com:27001\"}}",
              "{\"t\":{\"$date\":\"2020-05-19T19:10:58.877+00:00\"},\"s\":\"I\",  \"c\":\"CONNPOOL\", \"id\":22576,   \"ctx\":\"ReplicaSetMonitor-TaskExecutor\",\"msg\":\"Connecting\",\"attr\":{\"hostAndPort\":\"server4.example.com:27001\"}}",
              "{\"t\":{\"$date\":\"2020-05-19T19:10:58.877+00:00\"},\"s\":\"I\",  \"c\":\"CONNPOOL\", \"id\":22576,   \"ctx\":\"ReplicaSetMonitor-TaskExecutor\",\"msg\":\"Connecting\",\"attr\":{\"hostAndPort\":\"server5.example.com:27001\"}}",
              "{\"t\":{\"$date\":\"2020-05-19T19:10:58.877+00:00\"},\"s\":\"I\",  \"c\":\"CONNPOOL\", \"id\":22576,   \"ctx\":\"ReplicaSetMonitor-TaskExecutor\",\"msg\":\"Connecting\",\"attr\":{\"hostAndPort\":\"server6.example.com:27001\"}}",
              "{\"t\":{\"$date\":\"2020-05-19T19:10:58.877+00:00\"},\"s\":\"I\",  \"c\":\"NETWORK\",  \"id\":23015,   \"ctx\":\"listener\",\"msg\":\"Listening on\",\"attr\":{\"address\":\"/tmp/mongodb-27001.sock\"}}",
              "{\"t\":{\"$date\":\"2020-05-19T19:10:58.877+00:00\"},\"s\":\"I\",  \"c\":\"NETWORK\",  \"id\":23015,   \"ctx\":\"listener\",\"msg\":\"Listening on\",\"attr\":{\"address\":\"127.0.0.1\"}}",
              "{\"t\":{\"$date\":\"2020-05-19T19:10:58.877+00:00\"},\"s\":\"I\",  \"c\":\"NETWORK\",  \"id\":23016,   \"ctx\":\"listener\",\"msg\":\"Waiting for connections\",\"attr\":{\"port\":27001,\"ssl\":\"off\"}}",
              "{\"t\":{\"$date\":\"2020-05-19T19:15:10.392+00:00\"},\"s\":\"I\",  \"c\":\"NETWORK\",  \"id\":22943,   \"ctx\":\"listener\",\"msg\":\"connection accepted\",\"attr\":{\"remote\":\"127.0.0.1:35724\",\"sessionId\":67,\"connectionCount\":30}}",
              "{\"t\":{\"$date\":\"2020-05-19T19:15:10.393+00:00\"},\"s\":\"I\",  \"c\":\"NETWORK\",  \"id\":51800,   \"ctx\":\"conn67\",\"msg\":\"client metadata\",\"attr\":{\"remote\":\"127.0.0.1:35724\",\"client\":\"conn67\",\"doc\":{\"application\":{\"name\":\"MongoDB Shell\"},\"driver\":{\"name\":\"MongoDB Internal Client\",\"version\":\"4.4.0\"},\"os\":{\"type\":\"Linux\",\"name\":\"CentOS Linux release 8.0.1905 (Core) \",\"architecture\":\"x86_64\",\"version\":\"Kernel 4.18.0-80.11.2.el8_0.x86_64\"}}}}"
      ],
      "ok" : 1,
      "$gleStats" : {
              "lastOpTime" : Timestamp(<ts>),
              "electionId" : ObjectId(<id>)
      },
      "lastCommittedOpTime" : Timestamp(<ts>),
      "$configServerState" : {
              "opTime" : {
                      "ts" : Timestamp(<ts>),
                      "t" : Long(8)
               }
      },
      "$clusterTime" : {
              "clusterTime" : Timestamp(<ts>),
              "signature" : {
                      "hash" : BinData(<bin>),
                      "keyId" : Long(0)
               }
      },
      "operationTime" : Timestamp(<ts>)
}