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Merge pull request #160 from zalando-incubator/readme-stackenblocken 

Stackeblockenize the first section of the readme
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@ -6,21 +6,25 @@
The Postgres operator manages PostgreSQL clusters on Kubernetes using the [operator pattern](https://coreos.com/blog/introducing-operators.html). The Postgres operator manages PostgreSQL clusters on Kubernetes using the [operator pattern](https://coreos.com/blog/introducing-operators.html).
During the initial run it registers the [Custom Resource Definition (CRD)](https://kubernetes.io/docs/concepts/api-extension/custom-resources/#customresourcedefinitions) for Postgres. During the initial run it registers the [Custom Resource Definition (CRD)](https://kubernetes.io/docs/concepts/api-extension/custom-resources/#customresourcedefinitions) for Postgres.
The Postgresql CRD is essentially the schema that describes the contents of the manifests for deploying individual Postgresql clusters using Statefulsets and [Patroni](https://github.com/zalando/patroni). The PostgreSQL CRD is essentially the schema that describes the contents of the manifests for deploying individual
PostgreSQL clusters using StatefulSets and [Patroni](https://github.com/zalando/patroni).
Once the operator is running, it performs the following actions: Once the operator is running, it performs the following actions:
* watches for new Postgres cluster manifests and deploys corresponding clusters. * watches for new PostgreSQL cluster manifests and deploys corresponding clusters
* watches for updates to existing manifests and changes corresponding properties of the running clusters. * watches for updates to existing manifests and changes corresponding properties of the running clusters
* watches for deletes of the existing manifests and deletes corresponding database clusters. * watches for deletes of the existing manifests and deletes corresponding clusters
* acts on an update to the operator definition itself and changes the running clusters when necessary (i.e. when the docker image inside the operator definition has been updated.) * acts on an update to the operator definition itself and changes the running clusters when necessary
* periodically checks running clusters against the manifests and acts on the differences found. (i.e. when the docker image inside the operator definition has been updated)
* periodically checks running clusters against the manifests and acts on the differences found
For instance, when the user creates a new custom object of type postgresql by submitting a new manifest with kubectl, the operator fetches that object and creates the corresponding kubernetes structures (StatefulSets, Services, Secrets) according to its definition. For instance, when the user creates a new custom object of type ``postgresql`` by submitting a new manifest with
``kubectl``, the operator fetches that object and creates the corresponding Kubernetes structures
(StatefulSets, Services, Secrets) according to its definition.
Another example is changing the docker image inside the operator. In this case, the operator first goes to all Statefulsets Another example is changing the docker image inside the operator. In this case, the operator first goes to all StatefulSets
it manages and updates them with the new docker images; afterwards, all pods from each Statefulset are killed one by one it manages and updates them with the new docker images; afterwards, all pods from each StatefulSet are killed one by one
(rolling upgrade) and the replacements are spawned automatically by each Statefulset with the new docker image. (rolling upgrade) and the replacements are spawned automatically by each StatefulSet with the new docker image.
## Status ## Status
@ -29,42 +33,44 @@ Please, report any issues discovered to https://github.com/zalando-incubator/pos
## Running and testing the operator ## Running and testing the operator
The best way to test the operator is to run it in minikube. Minikube is a tool to run Kubernetes cluster locally. The best way to test the operator is to run it in [minikube](https://kubernetes.io/docs/getting-started-guides/minikube/).
Minikube is a tool to run Kubernetes cluster locally.
### Installing and starting minikube ### Installing and starting minikube
See [minikube installation guide](https://github.com/kubernetes/minikube/releases) See [minikube installation guide](https://github.com/kubernetes/minikube/releases)
Make sure you use the latest version of Minikube. Make sure you use the latest version of Minikube.
After the installation, issue the
After the installation, issue
$ minikube start $ minikube start
Note: if you are running on a Mac, make sure to use the [xhyve driver](https://github.com/kubernetes/minikube/blob/master/docs/drivers.md#xhyve-driver) Note: if you are running on a Mac, make sure to use the [xhyve driver](https://github.com/kubernetes/minikube/blob/master/docs/drivers.md#xhyve-driver)
instead of the default docker-machine one for performance reasons. instead of the default docker-machine one for performance reasons.
One you have it started successfully, use [the quickstart guide](https://github.com/kubernetes/minikube#quickstart) in order Once you have it started successfully, use [the quickstart guide](https://github.com/kubernetes/minikube#quickstart) in order
to test your that your setup is working. to test your that your setup is working.
Note: if you use multiple kubernetes clusters, you can switch to minikube with `kubectl config use-context minikube` Note: if you use multiple Kubernetes clusters, you can switch to Minikube with `kubectl config use-context minikube`
### Create ConfigMap ### Create ConfigMap
ConfigMap is used to store configuration of the operator ConfigMap is used to store the configuration of the operator
$ kubectl --context minikube create -f manifests/configmap.yaml $ kubectl --context minikube create -f manifests/configmap.yaml
### Deploying the operator ### Deploying the operator
First you need to install the service account definition in your minikube cluster. First you need to install the service account definition in your Minikube cluster.
$ kubectl --context minikube create -f manifests/serviceaccount.yaml $ kubectl --context minikube create -f manifests/serviceaccount.yaml
Next deploy the postgers-operator from the Docker image Zalando is using: Next deploy the postgres-operator from the docker image Zalando is using:
$ kubectl --context minikube create -f manifests/postgres-operator.yaml $ kubectl --context minikube create -f manifests/postgres-operator.yaml
If you perfer to build the image yourself follow up down below. If you prefer to build the image yourself follow up down below.
### Check if CustomResourceDefinition has been registered ### Check if CustomResourceDefinition has been registered
@ -74,11 +80,11 @@ If you perfer to build the image yourself follow up down below.
postgresqls.acid.zalan.do CustomResourceDefinition.v1beta1.apiextensions.k8s.io postgresqls.acid.zalan.do CustomResourceDefinition.v1beta1.apiextensions.k8s.io
### Create a new spilo cluster ### Create a new Spilo cluster
$ kubectl --context minikube create -f manifests/minimal-postgres-manifest.yaml $ kubectl --context minikube create -f manifests/minimal-postgres-manifest.yaml
### Watch Pods being created ### Watch pods being created
$ kubectl --context minikube get pods -w --show-labels $ kubectl --context minikube get pods -w --show-labels
@ -97,9 +103,11 @@ We can use the generated secret of the `postgres` robot user to connect to our `
The operator can be configured with the provided ConfigMap (`manifests/configmap.yaml`). The operator can be configured with the provided ConfigMap (`manifests/configmap.yaml`).
#### Use Taints and Tolerations for Dedicated Postgres Nodes #### 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 operator ConfigMap. 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 operator ConfigMap.
As an example you can set following node taint: As an example you can set following node taint:
@ -107,7 +115,7 @@ As an example you can set following node taint:
$ kubectl taint nodes <nodeName> postgres=:NoSchedule $ kubectl taint nodes <nodeName> postgres=:NoSchedule
``` ```
And configure the toleration for the Postgres pods by adding following line to the ConfigMap: And configure the toleration for the PostgreSQL pods by adding following line to the ConfigMap:
``` ```
apiVersion: v1 apiVersion: v1
@ -119,7 +127,7 @@ data:
... ...
``` ```
Or you can specify and/or overwrite the tolerations for each postgres instance in the postgres manifest: Or you can specify and/or overwrite the tolerations for each PostgreSQL instance in the manifest:
``` ```
apiVersion: "acid.zalan.do/v1" apiVersion: "acid.zalan.do/v1"
@ -134,7 +142,8 @@ spec:
effect: NoSchedule effect: NoSchedule
``` ```
Please be ware that the taint and toleration only ensures that no other pod gets scheduled to the "postgres" node but not that Postgres pods are placed on such a node. This can be achieved by setting a node affinity rule in the ConfigMap. Please be aware that the taint and toleration only ensures that no other pod gets scheduled to a PostgreSQL node
but not that PostgreSQL pods are placed on such a node. This can be achieved by setting a node affinity rule in the ConfigMap.
# Setup development environment # Setup development environment