CloudNativePG Plugin

CloudNativePG provides a plugin for kubectl to manage a cluster in Kubernetes.

Install

You can install the cnpg plugin using a variety of methods.

Note

For air-gapped systems, installation via package managers, using previously downloaded files, may be a good option.

Via the installation script

curl -sSfL \
  https://github.com/cloudnative-pg/cloudnative-pg/raw/main/hack/install-cnpg-plugin.sh | \
  sudo sh -s -- -b /usr/local/bin

Using the Debian or RedHat packages

In the releases section of the GitHub repository, you can navigate to any release of interest (pick the same or newer release than your CloudNativePG operator), and in it you will find an Assets section. In that section are pre-built packages for a variety of systems. As a result, you can follow standard practices and instructions to install them in your systems.

Debian packages

For example, let's install the 1.18.1 release of the plugin, for an Intel based 64 bit server. First, we download the right .deb file.

$ wget https://github.com/cloudnative-pg/cloudnative-pg/releases/download/v1.18.1/kubectl-cnpg_1.18.1_linux_x86_64.deb

Then, install from the local file using dpkg:

$ dpkg -i kubectl-cnpg_1.18.1_linux_x86_64.deb 
(Reading database ... 16102 files and directories currently installed.)
Preparing to unpack kubectl-cnpg_1.18.1_linux_x86_64.deb ...
Unpacking cnpg (1.18.1) over (1.18.1) ...
Setting up cnpg (1.18.1) ...

RPM packages

As in the example for .deb packages, let's install the 1.18.1 release for an Intel 64 bit machine. Note the --output flag to provide a file name.

curl -L https://github.com/cloudnative-pg/cloudnative-pg/releases/download/v1.18.1/kubectl-cnpg_1.18.1_linux_x86_64.rpm \
  --output kube-plugin.rpm

Then install with yum, and you're ready to use:

$ yum --disablerepo=* localinstall kube-plugin.rpm
yum --disablerepo=* localinstall kube-plugin.rpm    
Failed to set locale, defaulting to C.UTF-8
Dependencies resolved.
====================================================================================================
 Package            Architecture         Version                   Repository                  Size
====================================================================================================
Installing:
 cnpg               x86_64               1.18.1-1                  @commandline                14 M

Transaction Summary
====================================================================================================
Install  1 Package

Total size: 14 M
Installed size: 43 M
Is this ok [y/N]: y

Using Krew

If you already have Krew installed, you can simply run:

kubectl krew install cnpg

When a new version of the plugin is released, you can update the existing installation with:

kubectl krew update
kubectl krew upgrade cnpg

Supported Architectures

CloudNativePG Plugin is currently built for the following operating system and architectures:

  • Linux
  • amd64
  • arm 5/6/7
  • arm64
  • s390x
  • ppc64le
  • macOS
  • amd64
  • arm64
  • Windows
  • 386
  • amd64
  • arm 5/6/7
  • arm64

Use

Once the plugin was installed and deployed, you can start using it like this:

kubectl cnpg <command> <args...>

Generation of installation manifests

The cnpg plugin can be used to generate the YAML manifest for the installation of the operator. This option would typically be used if you want to override some default configurations such as number of replicas, installation namespace, namespaces to watch, and so on.

For details and available options, run:

kubectl cnpg install generate --help

The main options are:

  • -n: the namespace in which to install the operator (by default: cnpg-system)
  • --replicas: number of replicas in the deployment
  • --version: minor version of the operator to be installed, such as 1.17. If a minor version is specified, the plugin will install the latest patch version of that minor version. If no version is supplied the plugin will install the latest MAJOR.MINOR.PATCH version of the operator.
  • --watch-namespace: comma separated string containing the namespaces to watch (by default all namespaces)

An example of the generate command, which will generate a YAML manifest that will install the operator, is as follows:

kubectl cnpg install generate \
  -n king \
  --version 1.17 \
  --replicas 3 \
  --watch-namespace "albert, bb, freddie" \
  > operator.yaml

The flags in the above command have the following meaning: - -n king install the CNPG operator into the king namespace - --version 1.17 install the latest patch version for minor version 1.17 - --replicas 3 install the operator with 3 replicas - --watch-namespaces "albert, bb, freddie" have the operator watch for changes in the albert, bb and freddie namespaces only

Status

The status command provides an overview of the current status of your cluster, including:

  • general information: name of the cluster, PostgreSQL's system ID, number of instances, current timeline and position in the WAL
  • backup: point of recoverability, and WAL archiving status as returned by the pg_stat_archiver view from the primary - or designated primary in the case of a replica cluster
  • streaming replication: information taken directly from the pg_stat_replication view on the primary instance
  • instances: information about each Postgres instance, taken directly by each instance manager; in the case of a standby, the Current LSN field corresponds to the latest write-ahead log location that has been replayed during recovery (replay LSN).

Important

The status information above is taken at different times and at different locations, resulting in slightly inconsistent returned values. For example, the Current Write LSN location in the main header, might be different from the Current LSN field in the instances status as it is taken at two different time intervals.

kubectl cnpg status sandbox

Cluster in healthy state
Name:               sandbox
Namespace:          default
System ID:          7039966298120953877
PostgreSQL Image:   ghcr.io/cloudnative-pg/postgresql:15.3
Primary instance:   sandbox-2
Instances:          3
Ready instances:    3
Current Write LSN:  3AF/EAFA6168 (Timeline: 8 - WAL File: 00000008000003AF00000075)

Continuous Backup status
First Point of Recoverability:  Not Available
Working WAL archiving:          OK
Last Archived WAL:              00000008000003AE00000079   @   2021-12-14T10:16:29.340047Z
Last Failed WAL: -

Certificates Status
Certificate Name             Expiration Date                Days Left Until Expiration
----------------             ---------------                --------------------------
cluster-example-ca           2022-05-05 15:02:42 +0000 UTC  87.23
cluster-example-replication  2022-05-05 15:02:42 +0000 UTC  87.23
cluster-example-server       2022-05-05 15:02:42 +0000 UTC  87.23

Streaming Replication status
Name       Sent LSN      Write LSN     Flush LSN     Replay LSN    Write Lag        Flush Lag        Replay Lag       State      Sync State  Sync Priority
----       --------      ---------     ---------     ----------    ---------        ---------        ----------       -----      ----------  -------------
sandbox-1  3AF/EB0524F0  3AF/EB011760  3AF/EAFEDE50  3AF/EAFEDE50  00:00:00.004461  00:00:00.007901  00:00:00.007901  streaming  quorum      1
sandbox-3  3AF/EB0524F0  3AF/EB030B00  3AF/EB030B00  3AF/EB011760  00:00:00.000977  00:00:00.004194  00:00:00.008252  streaming  quorum      1

Instances status
Name       Database Size  Current LSN   Replication role  Status  QoS         Manager Version
----       -------------  -----------   ----------------  ------  ---         ---------------
sandbox-1  302 GB         3AF/E9FFFFE0  Standby (sync)    OK      Guaranteed  1.11.0
sandbox-2  302 GB         3AF/EAFA6168  Primary           OK      Guaranteed  1.11.0
sandbox-3  302 GB         3AF/EBAD5D18  Standby (sync)    OK      Guaranteed  1.11.0

You can also get a more verbose version of the status by adding --verbose or just -v

kubectl cnpg status sandbox --verbose

Cluster in healthy state
Name:               sandbox
Namespace:          default
System ID:          7039966298120953877
PostgreSQL Image:   ghcr.io/cloudnative-pg/postgresql:15.3
Primary instance:   sandbox-2
Instances:          3
Ready instances:    3
Current Write LSN:  3B1/61DE3158 (Timeline: 8 - WAL File: 00000008000003B100000030)

PostgreSQL Configuration
archive_command = '/controller/manager wal-archive --log-destination /controller/log/postgres.json %p'
archive_mode = 'on'
archive_timeout = '5min'
checkpoint_completion_target = '0.9'
checkpoint_timeout = '900s'
cluster_name = 'sandbox'
dynamic_shared_memory_type = 'sysv'
full_page_writes = 'on'
hot_standby = 'true'
jit = 'on'
listen_addresses = '*'
log_autovacuum_min_duration = '1s'
log_checkpoints = 'on'
log_destination = 'csvlog'
log_directory = '/controller/log'
log_filename = 'postgres'
log_lock_waits = 'on'
log_min_duration_statement = '1000'
log_rotation_age = '0'
log_rotation_size = '0'
log_statement = 'ddl'
log_temp_files = '1024'
log_truncate_on_rotation = 'false'
logging_collector = 'on'
maintenance_work_mem = '2GB'
max_connections = '1000'
max_parallel_workers = '32'
max_replication_slots = '32'
max_wal_size = '15GB'
max_worker_processes = '32'
pg_stat_statements.max = '10000'
pg_stat_statements.track = 'all'
port = '5432'
shared_buffers = '16GB'
shared_memory_type = 'sysv'
shared_preload_libraries = 'pg_stat_statements'
ssl = 'on'
ssl_ca_file = '/controller/certificates/client-ca.crt'
ssl_cert_file = '/controller/certificates/server.crt'
ssl_key_file = '/controller/certificates/server.key'
synchronous_standby_names = 'ANY 1 ("sandbox-1","sandbox-3")'
unix_socket_directories = '/controller/run'
wal_keep_size = '512MB'
wal_level = 'logical'
wal_log_hints = 'on'
cnpg.config_sha256 = '3cfa683e23fe513afaee7c97b50ce0628e0cc634bca8b096517538a9a4428efc'

PostgreSQL HBA Rules

# Grant local access
local all all peer map=local

# Require client certificate authentication for the streaming_replica user
hostssl postgres streaming_replica all cert
hostssl replication streaming_replica all cert
hostssl all cnpg_pooler_pgbouncer all cert

# Otherwise use the default authentication method
host all all all scram-sha-256


Continuous Backup status
First Point of Recoverability:  Not Available
Working WAL archiving:          OK
Last Archived WAL:              00000008000003B00000001D   @   2021-12-14T10:20:42.272815Z
Last Failed WAL: -

Streaming Replication status
Name       Sent LSN      Write LSN     Flush LSN     Replay LSN    Write Lag        Flush Lag        Replay Lag       State      Sync State  Sync Priority
----       --------      ---------     ---------     ----------    ---------        ---------        ----------       -----      ----------  -------------
sandbox-1  3B1/61E26448  3B1/61DF82F0  3B1/61DF82F0  3B1/61DF82F0  00:00:00.000333  00:00:00.000333  00:00:00.005484  streaming  quorum      1
sandbox-3  3B1/61E26448  3B1/61E26448  3B1/61DF82F0  3B1/61DF82F0  00:00:00.000756  00:00:00.000756  00:00:00.000756  streaming  quorum      1

Instances status
Name       Database Size  Current LSN   Replication role  Status  QoS         Manager Version
----       -------------  -----------   ----------------  ------  ---         ---------------
sandbox-1                 3B1/610204B8  Standby (sync)    OK      Guaranteed  1.11.0
sandbox-2                 3B1/61DE3158  Primary           OK      Guaranteed  1.11.0
sandbox-3                 3B1/62618470  Standby (sync)    OK      Guaranteed  1.11.0

The command also supports output in yaml and json format.

Promote

The meaning of this command is to promote a pod in the cluster to primary, so you can start with maintenance work or test a switch-over situation in your cluster

kubectl cnpg promote cluster-example cluster-example-2

Or you can use the instance node number to promote

kubectl cnpg promote cluster-example 2

Certificates

Clusters created using the CloudNativePG operator work with a CA to sign a TLS authentication certificate.

To get a certificate, you need to provide a name for the secret to store the credentials, the cluster name, and a user for this certificate

kubectl cnpg certificate cluster-cert --cnpg-cluster cluster-example --cnpg-user appuser

After the secrete it's created, you can get it using kubectl

kubectl get secret cluster-cert

And the content of the same in plain text using the following commands:

kubectl get secret cluster-cert -o json | jq -r '.data | map(@base64d) | .[]'

Restart

The kubectl cnpg restart command can be used in two cases:

  • requesting the operator to orchestrate a rollout restart for a certain cluster. This is useful to apply configuration changes to cluster dependent objects, such as ConfigMaps containing custom monitoring queries.

  • request a single instance restart, either in-place if the instance is the cluster's primary or deleting and recreating the pod if it is a replica.

# this command will restart a whole cluster in a rollout fashion
kubectl cnpg restart [clusterName]

# this command will restart a single instance, according to the policy above
kubectl cnpg restart [clusterName] [pod]

If the in-place restart is requested but the change cannot be applied without a switchover, the switchover will take precedence over the in-place restart. A common case for this will be a minor upgrade of PostgreSQL image.

Note

If you want ConfigMaps and Secrets to be automatically reloaded by instances, you can add a label with key cnpg.io/reload to it.

Reload

The kubectl cnpg reload command requests the operator to trigger a reconciliation loop for a certain cluster. This is useful to apply configuration changes to cluster dependent objects, such as ConfigMaps containing custom monitoring queries.

The following command will reload all configurations for a given cluster:

kubectl cnpg reload [cluster_name]

Maintenance

The kubectl cnpg maintenance command helps to modify one or more clusters across namespaces and set the maintenance window values, it will change the following fields:

  • .spec.nodeMaintenanceWindow.inProgress
  • .spec.nodeMaintenanceWindow.reusePVC

Accepts as argument set and unset using this to set the inProgress to true in case setand to false in case of unset.

By default, reusePVC is always set to false unless the --reusePVC flag is passed.

The plugin will ask for a confirmation with a list of the cluster to modify and their new values, if this is accepted this action will be applied to all the cluster in the list.

If you want to set in maintenance all the PostgreSQL in your Kubernetes cluster, just need to write the following command:

kubectl cnpg maintenance set --all-namespaces

And you'll have the list of all the cluster to update

The following are the new values for the clusters
Namespace  Cluster Name     Maintenance  reusePVC
---------  ------------     -----------  --------
default    cluster-example  true         false
default    pg-backup        true         false
test       cluster-example  true         false
Do you want to proceed? [y/n]: y

Report

The kubectl cnpg report command bundles various pieces of information into a ZIP file. It aims to provide the needed context to debug problems with clusters in production.

It has two sub-commands: operator and cluster.

report Operator

The operator sub-command requests the operator to provide information regarding the operator deployment, configuration and events.

Important

All confidential information in Secrets and ConfigMaps is REDACTED. The Data map will show the keys but the values will be empty. The flag -S / --stopRedaction will defeat the redaction and show the values. Use only at your own risk, this will share private data.

Note

By default, operator logs are not collected, but you can enable operator log collection with the --logs flag

  • deployment information: the operator Deployment and operator Pod
  • configuration: the Secrets and ConfigMaps in the operator namespace
  • events: the Events in the operator namespace
  • webhook configuration: the mutating and validating webhook configurations
  • webhook service: the webhook service
  • logs: logs for the operator Pod (optional, off by default) in JSON-lines format

The command will generate a ZIP file containing various manifest in YAML format (by default, but settable to JSON with the -o flag). Use the -f flag to name a result file explicitly. If the -f flag is not used, a default time-stamped filename is created for the zip file.

Note

The report plugin obeys kubectl conventions, and will look for objects constrained by namespace. The CNPG Operator will generally not be installed in the same namespace as the clusters. E.g. the default installation namespace is cnpg-system

kubectl cnpg report operator -n <namespace>

results in

Successfully written report to "report_operator_<TIMESTAMP>.zip" (format: "yaml")

With the -f flag set:

kubectl cnpg report operator -n <namespace> -f reportRedacted.zip

Unzipping the file will produce a time-stamped top-level folder to keep the directory tidy:

unzip reportRedacted.zip

will result in:

Archive:  reportRedacted.zip
   creating: report_operator_<TIMESTAMP>/
   creating: report_operator_<TIMESTAMP>/manifests/
  inflating: report_operator_<TIMESTAMP>/manifests/deployment.yaml
  inflating: report_operator_<TIMESTAMP>/manifests/operator-pod.yaml
  inflating: report_operator_<TIMESTAMP>/manifests/events.yaml
  inflating: report_operator_<TIMESTAMP>/manifests/validating-webhook-configuration.yaml
  inflating: report_operator_<TIMESTAMP>/manifests/mutating-webhook-configuration.yaml
  inflating: report_operator_<TIMESTAMP>/manifests/webhook-service.yaml
  inflating: report_operator_<TIMESTAMP>/manifests/cnpg-ca-secret.yaml
  inflating: report_operator_<TIMESTAMP>/manifests/cnpg-webhook-cert.yaml

If you activated the --logs option, you'd see an extra subdirectory:

Archive:  report_operator_<TIMESTAMP>.zip
  <snipped …>
  creating: report_operator_<TIMESTAMP>/operator-logs/
  inflating: report_operator_<TIMESTAMP>/operator-logs/cnpg-controller-manager-66fb98dbc5-pxkmh-logs.jsonl

Note

The plugin will try to get the PREVIOUS operator's logs, which is helpful when investigating restarted operators. In all cases, it will also try to get the CURRENT operator logs. If current and previous logs are available, it will show them both.

====== Begin of Previous Log =====
2023-03-28T12:56:41.251711811Z {"level":"info","ts":"2023-03-28T12:56:41Z","logger":"setup","msg":"Starting CloudNativePG Operator","version":"1.19.1","build":{"Version":"1.19.0+dev107","Commit":"cc9bab17","Date":"2023-03-28"}}
2023-03-28T12:56:41.251851909Z {"level":"info","ts":"2023-03-28T12:56:41Z","logger":"setup","msg":"Starting pprof HTTP server","addr":"0.0.0.0:6060"}
  <snipped …>

====== End of Previous Log =====
2023-03-28T12:57:09.854306024Z {"level":"info","ts":"2023-03-28T12:57:09Z","logger":"setup","msg":"Starting CloudNativePG Operator","version":"1.19.1","build":{"Version":"1.19.0+dev107","Commit":"cc9bab17","Date":"2023-03-28"}}
2023-03-28T12:57:09.854363943Z {"level":"info","ts":"2023-03-28T12:57:09Z","logger":"setup","msg":"Starting pprof HTTP server","addr":"0.0.0.0:6060"}

If the operator hasn't been restarted, you'll still see the ====== Begin … and ====== End … guards, with no content inside.

You can verify that the confidential information is REDACTED by default:

cd report_operator_<TIMESTAMP>/manifests/
head cnpg-ca-secret.yaml

data:
  ca.crt: ""
  ca.key: ""
metadata:
  creationTimestamp: "2022-03-22T10:42:28Z"
  managedFields:
  - apiVersion: v1
    fieldsType: FieldsV1
    fieldsV1:

With the -S (--stopRedaction) option activated, secrets are shown:

kubectl cnpg report operator -n <namespace> -f reportNonRedacted.zip -S

You'll get a reminder that you're about to view confidential information:

WARNING: secret Redaction is OFF. Use it with caution
Successfully written report to "reportNonRedacted.zip" (format: "yaml")

unzip reportNonRedacted.zip
head cnpg-ca-secret.yaml

data:
  ca.crt: LS0tLS1CRUdJTiBD…
  ca.key: LS0tLS1CRUdJTiBF…
metadata:
  creationTimestamp: "2022-03-22T10:42:28Z"
  managedFields:
  - apiVersion: v1
    fieldsType: FieldsV1

report Cluster

The cluster sub-command gathers the following:

  • cluster resources: the cluster information, same as kubectl get cluster -o yaml
  • cluster pods: pods in the cluster namespace matching the cluster name
  • cluster jobs: jobs, if any, in the cluster namespace matching the cluster name
  • events: events in the cluster namespace
  • pod logs: logs for the cluster Pods (optional, off by default) in JSON-lines format
  • job logs: logs for the Pods created by jobs (optional, off by default) in JSON-lines format

The cluster sub-command accepts the -f and -o flags, as the operator does. If the -f flag is not used, a default timestamped report name will be used. Note that the cluster information does not contain configuration Secrets / ConfigMaps, so the -S is disabled.

Note

By default, cluster logs are not collected, but you can enable cluster log collection with the --logs flag

Usage:

kubectl cnpg report cluster <clusterName> [flags]

Note that, unlike the operator sub-command, for the cluster sub-command you need to provide the cluster name, and very likely the namespace, unless the cluster is in the default one.

kubectl cnpg report cluster example -f report.zip -n example_namespace

and then:

unzip report.zip

Archive:  report.zip
   creating: report_cluster_example_<TIMESTAMP>/
   creating: report_cluster_example_<TIMESTAMP>/manifests/
  inflating: report_cluster_example_<TIMESTAMP>/manifests/cluster.yaml
  inflating: report_cluster_example_<TIMESTAMP>/manifests/cluster-pods.yaml
  inflating: report_cluster_example_<TIMESTAMP>/manifests/cluster-jobs.yaml
  inflating: report_cluster_example_<TIMESTAMP>/manifests/events.yaml

Remember that you can use the --logs flag to add the pod and job logs to the ZIP.

kubectl cnpg report cluster example -n example_namespace --logs

will result in:

Successfully written report to "report_cluster_example_<TIMESTAMP>.zip" (format: "yaml")

unzip report_cluster_<TIMESTAMP>.zip

Archive:  report_cluster_example_<TIMESTAMP>.zip
   creating: report_cluster_example_<TIMESTAMP>/
   creating: report_cluster_example_<TIMESTAMP>/manifests/
  inflating: report_cluster_example_<TIMESTAMP>/manifests/cluster.yaml
  inflating: report_cluster_example_<TIMESTAMP>/manifests/cluster-pods.yaml
  inflating: report_cluster_example_<TIMESTAMP>/manifests/cluster-jobs.yaml
  inflating: report_cluster_example_<TIMESTAMP>/manifests/events.yaml
   creating: report_cluster_example_<TIMESTAMP>/logs/
  inflating: report_cluster_example_<TIMESTAMP>/logs/cluster-example-full-1.jsonl
   creating: report_cluster_example_<TIMESTAMP>/job-logs/
  inflating: report_cluster_example_<TIMESTAMP>/job-logs/cluster-example-full-1-initdb-qnnvw.jsonl
  inflating: report_cluster_example_<TIMESTAMP>/job-logs/cluster-example-full-2-join-tvj8r.jsonl

Destroy

The kubectl cnpg destroy command helps remove an instance and all the associated PVCs from a Kubernetes cluster.

The optional --keep-pvc flag, if specified, allows you to keep the PVCs, while removing all metadata.ownerReferences that were set by the instance. Additionally, the cnpg.io/pvcStatus label on the PVCs will change from ready to detached to signify that they are no longer in use.

Running again the command without the --keep-pvc flag will remove the detached PVCs.

Usage:

kubectl cnpg destroy [CLUSTER_NAME] [INSTANCE_ID]

The following example removes the cluster-example-2 pod and the associated PVCs:

kubectl cnpg destroy cluster-example 2

Cluster hibernation

Sometimes you may want to suspend the execution of a CloudNativePG Cluster while retaining its data, then resume its activity at a later time. We've called this feature cluster hibernation.

Hibernation is only available via the kubectl cnpg hibernate [on|off] commands.

Hibernating a CloudNativePG cluster means destroying all the resources generated by the cluster, except the PVCs that belong to the PostgreSQL primary instance.

You can hibernate a cluster with:

kubectl cnpg hibernate on <cluster-name>

This will:

  1. shutdown every PostgreSQL instance
  2. detach the PVCs containing the data of the primary instance, and annotate them with the latest database status and the latest cluster configuration
  3. delete the Cluster resource, including every generated resource - except the aforementioned PVCs

When hibernated, a CloudNativePG cluster is represented by just a group of PVCs, in which the one containing the PGDATA is annotated with the latest available status, including content from pg_controldata.

Warning

A cluster having fenced instances cannot be hibernated, as fencing is part of the hibernation procedure too.

In case of error the operator will not be able to revert the procedure. You can still force the operation with:

kubectl cnpg hibernate on cluster-example --force

A hibernated cluster can be resumed with:

kubectl cnpg hibernate off <cluster-name>

Once the cluster has been hibernated, it's possible to show the last configuration and the status that PostgreSQL had after it was shut down. That can be done with:

kubectl cnpg hibernate status <cluster-name>

Benchmarking the database with pgbench

Pgbench can be run against an existing PostgreSQL cluster with following command:

kubectl cnpg pgbench <cluster-name> -- --time 30 --client 1 --jobs 1

Refer to the Benchmarking pgbench section for more details.

Benchmarking the storage with fio

fio can be run on an existing storage class with following command:

kubectl cnpg fio <fio-job-name> -n <namespace>

Refer to the Benchmarking fio section for more details.

Requesting a new base backup

The kubectl cnpg backup command requests a new physical base backup for an existing Postgres cluster by creating a new Backup resource.

The following example requests an on-demand backup for a given cluster:

kubectl cnpg backup [cluster_name]

The created backup will be named after the request time:

kubectl cnpg backup cluster-example
backup/cluster-example-20230121002300 created

Launching psql

The kubectl cnpg psql command starts a new PostgreSQL interactive front-end process (psql) connected to an existing Postgres cluster, as if you were running it from the actual pod. This means that you will be using the postgres user.

Important

As you will be connecting as postgres user, in production environments this method should be used with extreme care, by authorized personnel only.

kubectl cnpg psql cluster-example

psql (15.3 (Debian 15.3-1.pgdg110+1))
Type "help" for help.

postgres=#

By default, the command will connect to the primary instance. The user can select to work against a replica by using the --replica option:

kubectl cnpg psql --replica cluster-example
psql (15.3 (Debian 15.3-1.pgdg110+1))

Type "help" for help.

postgres=# select pg_is_in_recovery();
 pg_is_in_recovery
-------------------
 t
(1 row)

postgres=# \q

This command will start kubectl exec, and the kubectl executable must be reachable in your PATH variable to correctly work.

Snapshotting a Postgres cluster

The kubectl cnpg snapshot creates consistent snapshots of a Postgres Cluster by:

  1. choosing a replica Pod to work on
  2. fencing the replica
  3. taking the snapshot
  4. unfencing the replica

Warning

A cluster already having a fenced instance cannot be snapshotted.

At the moment, this command can be used only for clusters having at least one replica: that replica will be shut down by the fencing procedure to ensure the snapshot to be consistent (cold backup). As the development of declarative support for Kubernetes' VolumeSnapshot API continues, this limitation will be removed, allowing you to take online backups as business continuity requires.

Important

Even if the procedure will shut down a replica, the primary Pod will not be involved.

The kubectl cnpg snapshot command requires the cluster name:

kubectl cnpg snapshot cluster-example

waiting for cluster-example-3 to be fenced
waiting for VolumeSnapshot cluster-example-3-1682539624 to be ready to use
unfencing pod cluster-example-3

The VolumeSnapshot resource will be created with an empty VolumeSnapshotClass reference. That resource is intended by be used by the VolumeSnapshotClass configured as default.

A specific VolumeSnapshotClass can be requested via the -c option:

kubectl cnpg snapshot cluster-example -c longhorn