458 lines
15 KiB
Markdown
458 lines
15 KiB
Markdown
<h1>User Guide</h1>
|
|
|
|
Learn how to work with the Postgres Operator in a Kubernetes (K8s) environment.
|
|
|
|
## Create a manifest for a new PostgreSQL cluster
|
|
|
|
Make sure you have [set up](quickstart.md) the operator. Then you can create a
|
|
new Postgres cluster by applying manifest like this [minimal example](../manifests/minimal-postgres-manifest.yaml):
|
|
|
|
```yaml
|
|
apiVersion: "acid.zalan.do/v1"
|
|
kind: postgresql
|
|
metadata:
|
|
name: acid-minimal-cluster
|
|
spec:
|
|
teamId: "ACID"
|
|
volume:
|
|
size: 1Gi
|
|
numberOfInstances: 2
|
|
users:
|
|
# database owner
|
|
zalando:
|
|
- superuser
|
|
- createdb
|
|
|
|
# role for application foo
|
|
foo_user: # or 'foo_user: []'
|
|
|
|
#databases: name->owner
|
|
databases:
|
|
foo: zalando
|
|
postgresql:
|
|
version: "11"
|
|
```
|
|
|
|
Once you cloned the Postgres Operator [repository](https://github.com/zalando/postgres-operator)
|
|
you can find this example also in the manifests folder:
|
|
|
|
```bash
|
|
kubectl create -f manifests/minimal-postgres-manifest.yaml
|
|
```
|
|
|
|
Note, that the minimum volume size to properly run the `postgresql` resource is
|
|
`1Gi`. If a lower value is set in the manifest the operator will cancel ADD,
|
|
UPDATE or SYNC events on this resource with an error.
|
|
|
|
## Watch pods being created
|
|
|
|
```bash
|
|
kubectl get pods -w --show-labels
|
|
```
|
|
|
|
## Connect to PostgreSQL
|
|
|
|
With a `port-forward` on one of the database pods (e.g. the master) you can
|
|
connect to the PostgreSQL database. Use labels to filter for the master pod of
|
|
our test cluster.
|
|
|
|
```bash
|
|
# get name of master pod of acid-minimal-cluster
|
|
export PGMASTER=$(kubectl get pods -o jsonpath={.items..metadata.name} -l application=spilo,version=acid-minimal-cluster,spilo-role=master)
|
|
|
|
# set up port forward
|
|
kubectl port-forward $PGMASTER 6432:5432
|
|
```
|
|
|
|
Open another CLI and connect to the database. Use the generated secret of the
|
|
`postgres` robot user to connect to our `acid-minimal-cluster` master running
|
|
in Minikube:
|
|
|
|
```bash
|
|
export PGPASSWORD=$(kubectl get secret postgres.acid-minimal-cluster.credentials -o 'jsonpath={.data.password}' | base64 -d)
|
|
psql -U postgres -p 6432
|
|
```
|
|
|
|
## Defining database roles in the operator
|
|
|
|
Postgres Operator allows defining roles to be created in the resulting database
|
|
cluster. It covers three use-cases:
|
|
|
|
* `manifest roles`: create application roles specific to the cluster described
|
|
in the manifest.
|
|
* `infrastructure roles`: create application roles that should be automatically
|
|
created on every
|
|
cluster managed by the operator.
|
|
* `teams API roles`: automatically create users for every member of the team
|
|
owning the database cluster.
|
|
|
|
In the next sections, we will cover those use cases in more details.
|
|
|
|
### Manifest roles
|
|
|
|
Manifest roles are defined directly in the cluster manifest. See
|
|
[minimal postgres manifest](../manifests/minimal-postgres-manifest.yaml)
|
|
for an example of `zalando` role, defined with `superuser` and `createdb` flags.
|
|
|
|
Manifest roles are defined as a dictionary, with a role name as a key and a
|
|
list of role options as a value. For a role without any options it is best to
|
|
supply the empty list `[]`. It is also possible to leave this field empty as in
|
|
our example manifests. In certain cases such empty field may be missing later
|
|
removed by K8s [due to the `null` value it gets](https://kubernetes.io/docs/concepts/overview/object-management-kubectl/declarative-config/#how-apply-calculates-differences-and-merges-changes)
|
|
(`foobar_user:` is equivalent to `foobar_user: null`).
|
|
|
|
The operator accepts the following options: `superuser`, `inherit`, `login`,
|
|
`nologin`, `createrole`, `createdb`, `replication`, `bypassrls`.
|
|
|
|
By default, manifest roles are login roles (aka users), unless `nologin` is
|
|
specified explicitly.
|
|
|
|
The operator automatically generates a password for each manifest role and
|
|
places it in the secret named
|
|
`{username}.{team}-{clustername}.credentials.postgresql.acid.zalan.do` in the
|
|
same namespace as the cluster. This way, the application running in the
|
|
K8s cluster and connecting to Postgres can obtain the password right from the
|
|
secret, without ever sharing it outside of the cluster.
|
|
|
|
At the moment it is not possible to define membership of the manifest role in
|
|
other roles.
|
|
|
|
### Infrastructure roles
|
|
|
|
An infrastructure role is a role that should be present on every PostgreSQL
|
|
cluster managed by the operator. An example of such a role is a monitoring
|
|
user. There are two ways to define them:
|
|
|
|
* With the infrastructure roles secret only
|
|
* With both the the secret and the infrastructure role ConfigMap.
|
|
|
|
#### Infrastructure roles secret
|
|
|
|
The infrastructure roles secret is specified by the `infrastructure_roles_secret_name`
|
|
parameter. The role definition looks like this (values are base64 encoded):
|
|
|
|
```yaml
|
|
user1: ZGJ1c2Vy
|
|
password1: c2VjcmV0
|
|
inrole1: b3BlcmF0b3I=
|
|
```
|
|
|
|
The block above describes the infrastructure role 'dbuser' with password
|
|
'secret' that is a member of the 'operator' role. For the following definitions
|
|
one must increase the index, i.e. the next role will be defined as 'user2' and
|
|
so on. The resulting role will automatically be a login role.
|
|
|
|
Note that with definitions that solely use the infrastructure roles secret
|
|
there is no way to specify role options (like superuser or nologin) or role
|
|
memberships. This is where the ConfigMap comes into play.
|
|
|
|
#### Secret plus ConfigMap
|
|
|
|
A [ConfigMap](https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-configmap/)
|
|
allows for defining more details regarding the infrastructure roles. Therefore,
|
|
one should use the new style that specifies infrastructure roles using both the
|
|
secret and a ConfigMap. The ConfigMap must have the same name as the secret.
|
|
The secret should contain an entry with 'rolename:rolepassword' for each role.
|
|
|
|
```yaml
|
|
dbuser: c2VjcmV0
|
|
```
|
|
|
|
And the role description for that user should be specified in the ConfigMap.
|
|
|
|
```yaml
|
|
data:
|
|
dbuser: |
|
|
inrole: [operator, admin] # following roles will be assigned to the new user
|
|
user_flags:
|
|
- createdb
|
|
db_parameters: # db parameters, applied for this particular user
|
|
log_statement: all
|
|
```
|
|
|
|
One can allow membership in multiple roles via the `inrole` array parameter,
|
|
define role flags via the `user_flags` list and supply per-role options through
|
|
the `db_parameters` dictionary. All those parameters are optional.
|
|
|
|
Both definitions can be mixed in the infrastructure role secret, as long as
|
|
your new-style definition can be clearly distinguished from the old-style one
|
|
(for instance, do not name new-style roles `userN`).
|
|
|
|
Since an infrastructure role is created uniformly on all clusters managed by
|
|
the operator, it makes no sense to define it without the password. Such
|
|
definitions will be ignored with a prior warning.
|
|
|
|
See [infrastructure roles secret](../manifests/infrastructure-roles.yaml)
|
|
and [infrastructure roles configmap](../manifests/infrastructure-roles-configmap.yaml)
|
|
for the examples.
|
|
|
|
## Resource definition
|
|
|
|
The compute resources to be used for the Postgres containers in the pods can be
|
|
specified in the postgresql cluster manifest.
|
|
|
|
```yaml
|
|
apiVersion: "acid.zalan.do/v1"
|
|
kind: postgresql
|
|
metadata:
|
|
name: acid-minimal-cluster
|
|
spec:
|
|
resources:
|
|
requests:
|
|
cpu: 10m
|
|
memory: 100Mi
|
|
limits:
|
|
cpu: 300m
|
|
memory: 300Mi
|
|
```
|
|
|
|
The minimum limit to properly run the `postgresql` resource is `256m` for `cpu`
|
|
and `256Mi` for `memory`. If a lower value is set in the manifest the operator
|
|
will cancel ADD, UPDATE or SYNC events on this resource with an error. If no
|
|
resources are defined in the manifest the operator will obtain the configured
|
|
[default requests](reference/operator_parameters.md#kubernetes-resource-requests).
|
|
|
|
## Use taints and tolerations for dedicated PostgreSQL nodes
|
|
|
|
To ensure Postgres pods are running on nodes without any other application pods,
|
|
you can use [taints and tolerations](https://kubernetes.io/docs/concepts/configuration/taint-and-toleration/)
|
|
and configure the required toleration in the manifest.
|
|
|
|
```yaml
|
|
apiVersion: "acid.zalan.do/v1"
|
|
kind: postgresql
|
|
metadata:
|
|
name: acid-minimal-cluster
|
|
spec:
|
|
teamId: "ACID"
|
|
tolerations:
|
|
- key: postgres
|
|
operator: Exists
|
|
effect: NoSchedule
|
|
```
|
|
|
|
## How to clone an existing PostgreSQL cluster
|
|
|
|
You can spin up a new cluster as a clone of the existing one, using a clone
|
|
section in the spec. There are two options here:
|
|
|
|
* Clone directly from a source cluster using `pg_basebackup`
|
|
* Clone from an S3 bucket
|
|
|
|
### Clone directly
|
|
|
|
```yaml
|
|
apiVersion: "acid.zalan.do/v1"
|
|
kind: postgresql
|
|
|
|
metadata:
|
|
name: acid-test-cluster
|
|
spec:
|
|
clone:
|
|
cluster: "acid-batman"
|
|
```
|
|
|
|
Here `cluster` is a name of a source cluster that is going to be cloned. The
|
|
cluster to clone is assumed to be running and the clone procedure invokes
|
|
`pg_basebackup` from it. The operator will setup the cluster to be cloned to
|
|
connect to the service of the source cluster by name (if the cluster is called
|
|
test, then the connection string will look like host=test port=5432), which
|
|
means that you can clone only from clusters within the same namespace.
|
|
|
|
### Clone from S3
|
|
|
|
```yaml
|
|
apiVersion: "acid.zalan.do/v1"
|
|
kind: postgresql
|
|
|
|
metadata:
|
|
name: acid-test-cluster
|
|
spec:
|
|
clone:
|
|
uid: "efd12e58-5786-11e8-b5a7-06148230260c"
|
|
cluster: "acid-batman"
|
|
timestamp: "2017-12-19T12:40:33+01:00"
|
|
```
|
|
|
|
Here `cluster` is a name of a source cluster that is going to be cloned. A new
|
|
cluster will be cloned from S3, using the latest backup before the `timestamp`.
|
|
In this case, `uid` field is also mandatory - operator will use it to find a
|
|
correct key inside an S3 bucket. You can find this field in the metadata of the
|
|
source cluster:
|
|
|
|
```yaml
|
|
apiVersion: acid.zalan.do/v1
|
|
kind: postgresql
|
|
metadata:
|
|
name: acid-test-cluster
|
|
uid: efd12e58-5786-11e8-b5a7-06148230260c
|
|
```
|
|
|
|
Note that timezone is required for `timestamp`. Otherwise, offset is relative
|
|
to UTC, see [RFC 3339 section 5.6) 3339 section 5.6](https://www.ietf.org/rfc/rfc3339.txt).
|
|
|
|
For non AWS S3 following settings can be set to support cloning from other S3
|
|
implementations:
|
|
|
|
```yaml
|
|
apiVersion: "acid.zalan.do/v1"
|
|
kind: postgresql
|
|
metadata:
|
|
name: acid-test-cluster
|
|
spec:
|
|
clone:
|
|
uid: "efd12e58-5786-11e8-b5a7-06148230260c"
|
|
cluster: "acid-batman"
|
|
timestamp: "2017-12-19T12:40:33+01:00"
|
|
s3_endpoint: https://s3.acme.org
|
|
s3_access_key_id: 0123456789abcdef0123456789abcdef
|
|
s3_secret_access_key: 0123456789abcdef0123456789abcdef
|
|
s3_force_path_style: true
|
|
```
|
|
|
|
## Setting up a standby cluster
|
|
|
|
Standby clusters are like normal cluster but they are streaming from a remote
|
|
cluster. As the first version of this feature, the only scenario covered by
|
|
operator is to stream from a WAL archive of the master. Following the more
|
|
popular infrastructure of using Amazon's S3 buckets, it is mentioned as
|
|
`s3_wal_path` here. To start a cluster as standby add the following `standby`
|
|
section in the YAML file:
|
|
|
|
```yaml
|
|
spec:
|
|
standby:
|
|
s3_wal_path: "s3 bucket path to the master"
|
|
```
|
|
|
|
Things to note:
|
|
|
|
- An empty string in the `s3_wal_path` field of the standby cluster will result
|
|
in an error and no statefulset will be created.
|
|
- Only one pod can be deployed for stand-by cluster.
|
|
- To manually promote the standby_cluster, use `patronictl` and remove config
|
|
entry.
|
|
- There is no way to transform a non-standby cluster to a standby cluster
|
|
through the operator. Adding the standby section to the manifest of a running
|
|
Postgres cluster will have no effect. However, it can be done through Patroni
|
|
by adding the [standby_cluster](https://github.com/zalando/patroni/blob/bd2c54581abb42a7d3a3da551edf0b8732eefd27/docs/replica_bootstrap.rst#standby-cluster)
|
|
section using `patronictl edit-config`. Note that the transformed standby
|
|
cluster will not be doing any streaming. It will be in standby mode and allow
|
|
read-only transactions only.
|
|
|
|
## Sidecar Support
|
|
|
|
Each cluster can specify arbitrary sidecars to run. These containers could be
|
|
used for log aggregation, monitoring, backups or other tasks. A sidecar can be
|
|
specified like this:
|
|
|
|
```yaml
|
|
apiVersion: "acid.zalan.do/v1"
|
|
kind: postgresql
|
|
|
|
metadata:
|
|
name: acid-minimal-cluster
|
|
spec:
|
|
...
|
|
sidecars:
|
|
- name: "container-name"
|
|
image: "company/image:tag"
|
|
resources:
|
|
limits:
|
|
cpu: 500m
|
|
memory: 500Mi
|
|
requests:
|
|
cpu: 100m
|
|
memory: 100Mi
|
|
env:
|
|
- name: "ENV_VAR_NAME"
|
|
value: "any-k8s-env-things"
|
|
```
|
|
|
|
In addition to any environment variables you specify, the following environment
|
|
variables are always passed to sidecars:
|
|
|
|
- `POD_NAME` - field reference to `metadata.name`
|
|
- `POD_NAMESPACE` - field reference to `metadata.namespace`
|
|
- `POSTGRES_USER` - the superuser that can be used to connect to the database
|
|
- `POSTGRES_PASSWORD` - the password for the superuser
|
|
|
|
The PostgreSQL volume is shared with sidecars and is mounted at
|
|
`/home/postgres/pgdata`.
|
|
|
|
## InitContainers Support
|
|
|
|
Each cluster can specify arbitrary init containers to run. These containers can
|
|
be used to run custom actions before any normal and sidecar containers start.
|
|
An init container can be specified like this:
|
|
|
|
```yaml
|
|
apiVersion: "acid.zalan.do/v1"
|
|
kind: postgresql
|
|
|
|
metadata:
|
|
name: acid-minimal-cluster
|
|
spec:
|
|
...
|
|
initContainers:
|
|
- name: "container-name"
|
|
image: "company/image:tag"
|
|
env:
|
|
- name: "ENV_VAR_NAME"
|
|
value: "any-k8s-env-things"
|
|
```
|
|
|
|
`initContainers` accepts full `v1.Container` definition.
|
|
|
|
## Increase volume size
|
|
|
|
Postgres operator supports statefulset volume resize if you're using the
|
|
operator on top of AWS. For that you need to change the size field of the
|
|
volume description in the cluster manifest and apply the change:
|
|
|
|
```
|
|
apiVersion: "acid.zalan.do/v1"
|
|
kind: postgresql
|
|
|
|
metadata:
|
|
name: acid-test-cluster
|
|
spec:
|
|
volume:
|
|
size: 5Gi # new volume size
|
|
```
|
|
|
|
The operator compares the new value of the size field with the previous one and
|
|
acts on differences.
|
|
|
|
You can only enlarge the volume with the process described above, shrinking is
|
|
not supported and will emit a warning. After this update all the new volumes in
|
|
the statefulset are allocated according to the new size. To enlarge persistent
|
|
volumes attached to the running pods, the operator performs the following
|
|
actions:
|
|
|
|
* call AWS API to change the volume size
|
|
|
|
* connect to pod using `kubectl exec` and resize filesystem with `resize2fs`.
|
|
|
|
Fist step has a limitation, AWS rate-limits this operation to no more than once
|
|
every 6 hours. Note, that if the statefulset is scaled down before resizing the
|
|
new size is only applied to the volumes attached to the running pods. The
|
|
size of volumes that correspond to the previously running pods is not changed.
|
|
|
|
## Logical backups
|
|
|
|
You can enable logical backups from the cluster manifest by adding the following
|
|
parameter in the spec section:
|
|
|
|
```
|
|
enableLogicalBackup: true
|
|
```
|
|
|
|
The operator will create and sync a K8s cron job to do periodic logical backups
|
|
of this particular Postgres cluster. Due to the [limitation of K8s cron jobs](https://kubernetes.io/docs/concepts/workloads/controllers/cron-jobs/#cron-job-limitations)
|
|
it is highly advisable to set up additional monitoring for this feature; such
|
|
monitoring is outside the scope of operator responsibilities. See
|
|
[configuration reference](reference/cluster_manifest.md) and
|
|
[administrator documentation](administrator.md) for details on how backups are
|
|
executed.
|