Merge branch 'master' of https://github.com/zalando/postgres-operator into standby

docs/administrator.md

@@ -154,6 +154,22 @@ data:
   pod_antiaffinity_topology_key: "failure-domain.beta.kubernetes.io/zone"
 ```
 
+### Pod Disruption Budget
+
+By default the operator uses a PodDisruptionBudget (PDB) to protect the cluster
+from voluntarily disruptions and hence unwanted DB downtime. The `MinAvailable`
+parameter of the PDB is set to `1` which prevents killing masters in single-node
+clusters and/or the last remaining running instance in a multi-node cluster.
+
+The PDB is only relaxed in two scenarios:
+* If a cluster is scaled down to `0` instances (e.g. for draining nodes)
+* If the PDB is disabled in the configuration (`enable_pod_disruption_budget`)
+
+The PDB is still in place having `MinAvailable` set to `0`. If enabled it will
+be automatically set to `1` on scale up. Disabling PDBs helps avoiding blocking
+Kubernetes upgrades in managed K8s environments at the cost of prolonged DB
+downtime. See PR #384 for the use case.
+
 ### Add cluster-specific labels
 
 In some cases, you might want to add `labels` that are specific to a given
@@ -317,3 +333,19 @@ The operator can manage k8s cron jobs to run logical backups of Postgres cluster
 4. You may use your own image by overwriting the relevant field in the operator configuration. Any such image must ensure the logical backup is able to finish [in presence of pod restarts](https://kubernetes.io/docs/concepts/workloads/controllers/jobs-run-to-completion/#handling-pod-and-container-failures) and [simultaneous invocations](https://kubernetes.io/docs/concepts/workloads/controllers/cron-jobs/#cron-job-limitations) of the backup cron job.
 
 5. For that feature to work, your RBAC policy must enable operations on the `cronjobs` resource from the `batch` API group for the operator service account. See [example RBAC](../manifests/operator-service-account-rbac.yaml)
+
+## Access to cloud resources from clusters in non cloud environment
+
+To access cloud resources like S3 from a cluster in a bare metal setup you can use
+`additional_secret_mount` and `additional_secret_mount_path` config parameters.
+With this you can provision cloud credentials to the containers in the pods of the StatefulSet.
+This works this way that it mounts a volume from the given secret in the pod and this can
+then accessed in the container over the configured mount path. Via [Custum Pod Environment Variables](#custom-pod-environment-variables)
+you can then point the different cloud sdk's (aws, google etc.) to this mounted secret.
+With this credentials the cloud sdk can then access cloud resources to upload logs etc.
+
+A secret can be pre provisioned in different ways:
+
+* Generic secret created via `kubectl create secret generic some-cloud-creds --from-file=some-cloud-credentials-file.json`
+
+* Automaticly provisioned via a Controller like [kube-aws-iam-controller](https://github.com/mikkeloscar/kube-aws-iam-controller). This controller would then also rotate the credentials. Please visit the documention for more information.

docs/reference/cluster_manifest.md

@@ -285,6 +285,9 @@ properties of the persistent storage that stores postgres data.
   documentation](https://kubernetes.io/docs/concepts/storage/storage-classes/)
   for the details on storage classes. Optional.
 
+* **subPath**
+  Subpath to use when mounting volume into Spilo container
+
 ### Sidecar definitions
 
 Those parameters are defined under the `sidecars` key. They consist of a list

docs/reference/operator_parameters.md

@@ -161,6 +161,13 @@ configuration they are grouped under the `kubernetes` key.
   replaced by the cluster name. Only the `{cluster}` placeholders is allowed in
   the template.
 
+* **enable_pod_disruption_budget**
+  PDB is enabled by default to protect the cluster from voluntarily disruptions
+  and hence unwanted DB downtime. However, on some cloud providers it could be
+  necessary to temporarily disabled it, e.g. for node updates. See
+  [admin docs](../administrator.md#pod-disruption-budget) for more information.
+  Default is true.
+
 * **secret_name_template**
   a template for the name of the database user secrets generated by the
   operator. `{username}` is replaced with name of the secret, `{cluster}` with
@@ -400,6 +407,12 @@ yet officially supported.
 * **aws_region**
   AWS region used to store ESB volumes. The default is `eu-central-1`.
 
+* **additional_secret_mount**
+  Additional Secret (aws or gcp credentials) to mount in the pod. The default is empty.
+
+* **additional_secret_mount_path**
+  Path to mount the above Secret in the filesystem of the container(s). The default is empty.
+
 ## Debugging the operator
 
 Options to aid debugging of the operator itself. Grouped under the `debug` key.