fix gcp instructions for setting up the storage class (#111)

docs/configure.md

@@ -400,39 +400,42 @@ Sourcegraph expects there to be storage class named `sourcegraph` that it uses f
    #  zones: us-central1-a
    ```
 
-1. Read through the [Kubernetes storage class documentation](https://kubernetes.io/docs/concepts/storage/storage-classes/), and fill in the `provisioner` and `parameters` fields in `base/sourcegraph.StorageClass.yaml` with the correct values for your hosting provider (e.x.: [GCP](https://kubernetes.io/docs/concepts/storage/storage-classes/#gce), [AWS](https://kubernetes.io/docs/concepts/storage/storage-classes/#aws), [Azure](https://kubernetes.io/docs/concepts/storage/storage-classes/#azure-disk)).
+1. Read through the [Kubernetes storage class documentation](https://kubernetes.io/docs/concepts/storage/storage-classes/), and fill in the `provisioner` and `parameters` fields in `base/sourcegraph.StorageClass.yaml` with the correct values for your hosting provider (e.x.: [GCP](https://kubernetes.io/docs/concepts/storage/storage-classes/#gce-pd), [AWS](https://kubernetes.io/docs/concepts/storage/storage-classes/#aws), [Azure](https://kubernetes.io/docs/concepts/storage/storage-classes/#azure-disk)).
 
-   **We highly recommend that the storage class use SSDs as the underlying disk type.**
+   - Note that if you're using GCP with Kubernetes `v1.9.*`, you should omit the `replication-type` parameter mentioned in [the documentation](https://kubernetes.io/docs/concepts/storage/storage-classes/#gce-pd) from your `base/sourcegraph.StorageClass.yaml` file. That field wasn't added until Kubernetes `v.1.10.*+`, and you'll see errors like the following if you try to use it with an older version:
 
-   Using the snippets below will create a storage class backed by SSDs:
+     ```
+     Failed to provision volume with StorageClass "sourcegraph": invalid option "replication-type" for volume plugin kubernetes.io/gce-pd
+     ```
 
-   - [GCP](https://kubernetes.io/docs/concepts/storage/storage-classes/#gce):
+   - **We highly recommend that the storage class use SSDs as the underlying disk type.** Using the snippets below will create a storage class backed by SSDs:
 
-     ```yaml
-     # base/sourcegraph.StorageClass.yaml
-     provisioner: kubernetes.io/gce-pd
-     parameters:
-       type: pd-ssd
-     ```
+     - [GCP](https://kubernetes.io/docs/concepts/storage/storage-classes/#gce-pd):
 
-   - [AWS](https://kubernetes.io/docs/concepts/storage/storage-classes/#aws):
+       ```yaml
+       # base/sourcegraph.StorageClass.yaml
+       provisioner: kubernetes.io/gce-pd
+       parameters:
+         type: pd-ssd
+       ```
 
-     ```yaml
-     # base/sourcegraph.StorageClass.yaml
-     provisioner: kubernetes.io/aws-ebs
-     parameters:
-       type: gp2
-     ```
+     - [AWS](https://kubernetes.io/docs/concepts/storage/storage-classes/#aws):
 
-   - [Azure](https://kubernetes.io/docs/concepts/storage/storage-classes/#azure-disk):
+       ```yaml
+       # base/sourcegraph.StorageClass.yaml
+       provisioner: kubernetes.io/aws-ebs
+       parameters:
+         type: gp2
+       ```
 
-     ```yaml
-     # base/sourcegraph.StorageClass.yaml
-     provisioner: kubernetes.io/azure-disk
-     parameters:
-       storageaccounttype: Premium_LRS
-     ```
+     - [Azure](https://kubernetes.io/docs/concepts/storage/storage-classes/#azure-disk):
 
+       ```yaml
+       # base/sourcegraph.StorageClass.yaml
+       provisioner: kubernetes.io/azure-disk
+       parameters:
+         storageaccounttype: Premium_LRS
+       ```
 
 1. Commit `base/sourcegraph.StorageClass.yaml` to your fork.
 
@@ -451,7 +454,7 @@ find . -name "*PersistentVolumeClaim.yaml" -exec sh -c "cat {} | yj | jq '.spec.
 GS=base/gitserver/gitserver.StatefulSet.yaml
 
 cat $GS | yj | jq  --arg STORAGE_CLASS_NAME $STORAGE_CLASS_NAME '.spec.volumeClaimTemplates = (.spec.volumeClaimTemplates | map( . * {spec:{storageClassName: $STORAGE_CLASS_NAME }}))' | jy -o $GS
-````
+```
 
 ## Configure Lightstep tracing