Version: Cloud

Monitor Clickhouse DB on Kubernetes

Overview

Clickhouse database can be monitored in SnappyFlow using Prometheus exporter.

Clickhouse monitoring with Prometheus

Refer to Prometheus Exporter document to understand how SnappyFlow monitors using Prometheus exporters.

Pre-requisites

Prometheus exporter is deployed as a side-car container in the application container and the exporter port is accessible to sfPod.

Configuration 

Add the following configuration to the Clickhouse Deployment.yaml file.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: clickhouse-operator
spec:
  selector:
    matchLabels:
      app: clickhouse-operator
  template:
    metadata:
      annotations:
        prometheus.io/port: "8888"
        prometheus.io/scrape: "true"
      labels:
        app: clickhouse-operator
    spec:
      containers:
      - env:
        - name: OPERATOR_POD_NODE_NAME
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: spec.nodeName
        image: altinity/clickhouse-operator:0.10.0
        imagePullPolicy: Always
        name: clickhouse-operator
        volumeMounts:
        - mountPath: /etc/clickhouse-operator
          name: etc-clickhouse-operator-folder
        - mountPath: /etc/clickhouse-operator/conf.d
          name: etc-clickhouse-operator-confd-folder
        - mountPath: /etc/clickhouse-operator/config.d
          name: etc-clickhouse-operator-configd-folder
        - mountPath: /etc/clickhouse-operator/templates.d
          name: etc-clickhouse-operator-templatesd-folder
        - mountPath: /etc/clickhouse-operator/users.d
          name: etc-clickhouse-operator-usersd-folder
      - image: altinity/metrics-exporter:0.10.0
        imagePullPolicy: Always
        name: metrics-exporter
        ports:
        - containerPort: 8888
          name: metrics
          protocol: TCP
        volumeMounts:
        - mountPath: /etc/clickhouse-operator
          name: etc-clickhouse-operator-folder
        - mountPath: /etc/clickhouse-operator/conf.d
          name: etc-clickhouse-operator-confd-folder
        - mountPath: /etc/clickhouse-operator/config.d
          name: etc-clickhouse-operator-configd-folder
        - mountPath: /etc/clickhouse-operator/templates.d
          name: etc-clickhouse-operator-templatesd-folder
        - mountPath: /etc/clickhouse-operator/users.d
          name: etc-clickhouse-operator-usersd-folder
      volumes:
      - configMap:
          defaultMode: 420
          name: etc-clickhouse-operator-files
        name: etc-clickhouse-operator-folder
      - configMap:
          defaultMode: 420
          name: etc-clickhouse-operator-confd-files
        name: etc-clickhouse-operator-confd-folder
      - configMap:
          defaultMode: 420
          name: etc-clickhouse-operator-configd-files
        name: etc-clickhouse-operator-configd-folder
      - configMap:
          defaultMode: 420
          name: etc-clickhouse-operator-templatesd-files
        name: etc-clickhouse-operator-templatesd-folder
      - configMap:
          defaultMode: 420
          name: etc-clickhouse-operator-usersd-files
        name: etc-clickhouse-operator-usersd-folder
  

View Database Metrics

Follow the below steps to view the metrics collected Clickhouse DB.

Go to the Application tab in SnappyFlow and navigate to your Project > Application > Dashboard.
You can view the database metrics in the Metrics section.
note
Once the Clickhouse configuration settings are done, the Clickhouse plugin will be automatically detected within the Metrics section.
To access the unprocessed data gathered from the plugins, navigate to the Browse data section and choose the Index: Metric, Instance: Endpoint, Plugin, and Document Type.

Template	Plugin	Document Type
Clickhouse_Kube_Prom	kube-prom-clickhouse	clusterDetails, hostDetails, tableStats

Metric List

Cluster Details

Name	Description
DNSError	Total count of errors in DNS resolution
DelayedInserts	Number of times the INSERT of a block to a MergeTree table was throttled due to high number of active data parts for partition.
ContextLocks	Number of times the lock of Context was acquired or tried to acquire. This is global lock.
MergedUncompressedBytes	Uncompressed bytes (for columns as they stored in memory) that was read for background merges. This is the number before merge.
MergesTimeMilliseconds	Total time spent for background merges.
DiskReadElapsedMicroseconds	Total time spent waiting for read syscall. This include reads from page cache.
DiskWriteElapsedMicroseconds	Total time spent waiting for write syscall. This include writes to page cache.
MergeTreeDataWriterCompressedBytes	Bytes written to filesystem for data INSERTed to MergeTree tables.
MergeTreeDataWriterRows	Number of rows INSERTed to MergeTree tables.
NumberOfTables	Number of tables
InsertedBytes	Number of bytes (uncompressed; for columns as they stored in memory) INSERTed to all tables.
InsertedRows	Number of rows INSERTed to all tables.
Merge	Number of launched background merges.
Query	Number of queries to be interpreted and potentially executed. Does not include queries that failed to parse or were rejected due to AST size limits, quota limits or limits on the number of simultaneously running queries. May include internal queries initiated by ClickHouse itself. Does not count subqueries.
FailedQuery	Number of failed queries.
SelectQuery	Same as Query, but only for SELECT queries.
FailedSelectQuery	Same as FailedQuery, but only for SELECT queries.
fileopen	Number of files opened.
NumberOfDatabases	Number of databases
ReadonlyReplica	Number of Replicated tables that are currently in readonly state due to re-initialization after ZooKeeper session loss or due to startup without ZooKeeper configured.
OSCPUWaitMicroseconds	Total time a thread was ready for execution but waiting to be scheduled by OS, from the OS point of view.
OSIOWaitMicroseconds	Total time a thread spent waiting for a result of IO operation, from the OS point of view. This is real IO that doesn't include page cache.
UserTimeMicroseconds	Total time spent in processing (queries and other tasks) threads executing CPU instructions in user space. This include time CPU pipeline was stalled due to cache misses, branch mispredictions, hyper-threading, etc.
OSWriteBytes	Number of bytes written to disks or block devices. Doesn't include bytes that are in page cache dirty pages. May not include data that was written by OS asynchronously.
QueryDuration (Prom Metric: chi_clickhouse_event_RealTimeMicroseconds)	Total (wall clock) time spent in processing (queries and other tasks) threads (not that this is a sum).
MergedRows	Rows read for background merges. This is the number of rows before merge.
LongestRunningQuery	Longest running query time
HardPageFaults	An exception that the memory management unit (MMU) raises when a process accesses a memory page without proper preparations

Host Details

Name	Description
DNSError	Total count of errors in DNS resolution
Httpconnection	The number of connections to HTTP server
CompressedReadBufferBlocks	Number of compressed blocks (the blocks of data that are compressed independent of each other) read from compressed sources (files, network)
CompressedReadBufferBytes	Number of uncompressed bytes (the number of bytes after decompression) read from compressed sources (files, network).
DiskReadElapsedMicroseconds	Total time spent waiting for read syscall. This include reads from page cache.
DiskWriteElapsedMicroseconds	Total time spent waiting for write syscall. This include writes to page cache.
MergeTreeDataWriterCompressedBytes	Bytes written to filesystem for data INSERTed to MergeTree tables.
MergeTreeDataWriterRows	Number of rows INSERTed to MergeTree tables.
DistributedConnectionFailAtAll	Total count when distributed connection fails after all retries finished
InsertQuery	Same as Query, but only for INSERT queries.
NumberOfTables	Number of tables
Query Threads	Number of query processing threads
ZooKeeperUserExceptions	ZooKeeper User Exceptions
BackgroundDistributedSchedulePoolTask	Number of active tasks in BackgroundDistributedSchedulePool. This pool is used for distributed sends that is done in background.
BackgroundMovePoolTask	Number of active tasks in BackgroundProcessingPool for moves
BackgroundSchedulePoolTask	Number of active tasks in BackgroundSchedulePool. This pool is used for periodic ReplicatedMergeTree tasks, like cleaning old data parts, altering data parts, replica re-initialization, etc
ContextLocks	Number of times the lock of Context was acquired or tried to acquire. This is global lock.
ContextLockWait	Number of threads waiting for lock in Context. This is global lock.
GlobalThreadActive	Number of threads in global thread pool running a task.
GlobalThreadTotal	Number of threads in global thread pool.
LocalThreadActive	Number of threads in local thread pools running a task.
LocalThreadTotal	Number of threads in local thread pool.
PartMutation	Number of mutations (ALTER DELETE/UPDATE)
FailedQuery	Number of failed queries.
SelectQuery	Same as Query, but only for SELECT queries.
FailedSelectQuery	Same as FailedQuery, but only for SELECT queries.
Fileopen	Number of files opened.
MergedRows	Rows read for background merges. This is the number of rows before merge.
Merge	Number of launched background merges.
Query	Number of queries to be interpreted and potentially executed. Does not include queries that failed to parse or were rejected due to AST size limits, quota limits or limits on the number of simultaneously running queries. May include internal queries initiated by ClickHouse itself. Does not count subqueries.
InsertedBytes	Number of bytes (uncompressed; for columns as they stored in memory) INSERTed to all tables.
InsertedRows	Number of rows INSERTed to all tables.
MergedUncompressedBytes	Uncompressed bytes (for columns as they stored in memory) that was read for background merges. This is the number before merge.
MergesTimeMilliseconds	Total time spent for background merges.
ReplicasMaxInsertsInQueue
ReplicasMaxMergesInQueue
ReplicasSumInsertsInQueue
ReplicasSumMergesInQueue
jemalloc_background_thread_num_runs
MaxPartCountForPartition
MemoryTrackingForMerges	Total amount of memory (bytes) allocated for background merges. Included in MemoryTrackingInBackgroundProcessingPool. Note that this value may include a drift when the memory was allocated in a context of background processing pool and freed in other context or vice-versa. This happens naturally due to caches for tables indexes and doesn't indicate memory leaks.
ZooKeeperWaitMicroseconds
ArenaAllocBytes

TableStats

Name	Description
Table	Name of the table
Database	Name of the database
NumPartitions	Number of partitions of the table
NumTableParts	Number of parts of the table
TableSize	Table size in bytes
NumRow	Number of rows in the table

Monitor Clickhouse DB on Kubernetes

Overview​

Clickhouse monitoring with Prometheus​

Pre-requisites​

Configuration ​

View Database Metrics​

Metric List​

Cluster Details​

Host Details​

TableStats​