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+# Gerrit on Kubernetes
+
+Gerrit is a web-based code review tool, which acts as a Git server. This helm
+chart provides a Gerrit setup that can be deployed on Kubernetes.
+In addition, the chart provides a CronJob to perform Git garbage collection.
+
+***note
+Gerrit versions before 3.0 are no longer supported, since the support of ReviewDB
+was removed.
+***
+
+## Prerequisites
+
+- Helm (>= version 3.0)
+
+ (Check out [this guide](https://docs.helm.sh/using_helm/#quickstart-guide)
+ how to install and use helm.)
+
+- Access to a provisioner for persistent volumes with `Read Write Many (RWM)`-
+ capability.
+
+ A list of applicaple volume types can be found
+ [here](https://kubernetes.io/docs/concepts/storage/persistent-volumes/#access-modes).
+ This project was developed using the
+ [NFS-server-provisioner helm chart](https://github.com/helm/charts/tree/master/stable/nfs-server-provisioner),
+ a NFS-provisioner deployed in the Kubernetes cluster itself. Refer to
+ [this guide](/helm-charts/gerrit/docs/nfs-provisioner.md) of how to
+ deploy it in context of this project.
+
+- A domain name that is configured to point to the IP address of the node running
+ the Ingress controller on the kubernetes cluster (as described
+ [here](http://alesnosek.com/blog/2017/02/14/accessing-kubernetes-pods-from-outside-of-the-cluster/)).
+
+- (Optional: Required, if SSL is configured)
+ A [Java keystore](https://gerrit-review.googlesource.com/Documentation/config-gerrit.html#httpd.sslKeyStore)
+ to be used by Gerrit.
+
+## Installing the Chart
+
+***note
+**ATTENTION:** The value for `ingress.host` is required for rendering
+the chart's templates. The nature of the value does not allow defaults.
+Thus a custom `values.yaml`-file setting this value is required!
+***
+
+To install the chart with the release name `gerrit`, execute:
+
+```sh
+cd $(git rev-parse --show-toplevel)/helm-charts
+helm install \
+ gerrit \ # release name
+ ./gerrit \ # path to chart
+ -f <path-to-custom-values>.yaml
+```
+
+The command deploys the Gerrit instance on the current Kubernetes cluster.
+The [configuration section](#Configuration) lists the parameters that can be
+configured during installation.
+
+## Configuration
+
+The following sections list the configurable values in `values.yaml`. To configure
+a Gerrit setup, make a copy of the `values.yaml`-file and change the parameters
+as needed. The configuration can be applied by installing the chart as described
+[above](#Installing-the-chart).
+
+In addition, single options can be set without creating a custom `values.yaml`:
+
+```sh
+cd $(git rev-parse --show-toplevel)/helm-charts
+helm install \
+ gerrit \ # release name
+ ./gerrit \ # path to chart
+ --set=gitRepositoryStorage.size=100Gi
+```
+
+### Container images
+
+| Parameter | Description | Default |
+|-----------|-------------|---------|
+| `images.busybox.registry` | The registry to pull the busybox container images from | `docker.io` |
+| `images.busybox.tag` | The busybox image tag to use | `latest` |
+| `images.registry.name` | The image registry to pull the container images from | `` |
+| `images.registry.ImagePullSecret.name` | Name of the ImagePullSecret | `image-pull-secret` (if empty no image pull secret will be deployed) |
+| `images.registry.ImagePullSecret.create` | Whether to create an ImagePullSecret | `false` |
+| `images.registry.ImagePullSecret.username` | The image registry username | `nil` |
+| `images.registry.ImagePullSecret.password` | The image registry password | `nil` |
+| `images.version` | The image version (image tag) to use | `latest` |
+| `images.imagePullPolicy` | Image pull policy | `Always` |
+| `images.additionalImagePullSecrets` | Additional image pull policies that pods should use | `[]` |
+
+### Labels
+
+| Parameter | Description | Default |
+|-----------|-------------|---------|
+| `additionalLabels` | Additional labels for resources managed by this Helm chart | `{}` |
+
+### Storage classes
+
+For information of how a `StorageClass` is configured in Kubernetes, read the
+[official Documentation](https://kubernetes.io/docs/concepts/storage/storage-classes/#introduction).
+
+| Parameter | Description | Default |
+|-----------|-------------|---------|
+| `storageClasses.default.name` | The name of the default StorageClass (RWO) | `default` |
+| `storageClasses.default.create` | Whether to create the StorageClass | `false` |
+| `storageClasses.default.provisioner` | Provisioner of the StorageClass | `kubernetes.io/aws-ebs` |
+| `storageClasses.default.reclaimPolicy` | Whether to `Retain` or `Delete` volumes, when they become unbound | `Delete` |
+| `storageClasses.default.parameters` | Parameters for the provisioner | `parameters.type: gp2`, `parameters.fsType: ext4` |
+| `storageClasses.default.mountOptions` | The mount options of the default StorageClass | `[]` |
+| `storageClasses.default.allowVolumeExpansion` | Whether to allow volume expansion. | `false` |
+| `storageClasses.shared.name` | The name of the shared StorageClass (RWM) | `shared-storage` |
+| `storageClasses.shared.create` | Whether to create the StorageClass | `false` |
+| `storageClasses.shared.provisioner` | Provisioner of the StorageClass | `nfs` |
+| `storageClasses.shared.reclaimPolicy` | Whether to `Retain` or `Delete` volumes, when they become unbound | `Delete` |
+| `storageClasses.shared.parameters` | Parameters for the provisioner | `parameters.mountOptions: vers=4.1` |
+| `storageClasses.shared.mountOptions` | The mount options of the shared StorageClass | `[]` |
+| `storageClasses.shared.allowVolumeExpansion` | Whether to allow volume expansion. | `false` |
+
+### Network policies
+
+| Parameter | Description | Default |
+|-----------|-------------|---------|
+| `networkPolicies.enabled` | Whether to enable preconfigured NetworkPolicies | `false` |
+| `networkPolicies.dnsPorts` | List of ports used by DNS-service (e.g. KubeDNS) | `[53, 8053]` |
+
+The NetworkPolicies provided here are quite strict and do not account for all
+possible scenarios. Thus, custom NetworkPolicies have to be added, e.g. for
+allowing Gerrit to replicate to a Gerrit replica. By default, the egress traffic
+of the gerrit pod is blocked, except for connections to the DNS-server.
+Thus, replication which requires Gerrit to perform git pushes to the replica will
+not work. The chart provides the possibility to define custom rules for egress-
+traffic of the gerrit pod under `gerrit.networkPolicy.egress`.
+Depending on the scenario, there are different ways to allow the required
+connections. The easiest way is to allow all egress-traffic for the gerrit
+pods:
+
+```yaml
+gerrit:
+ networkPolicy:
+ egress:
+ - {}
+```
+
+If the remote that is replicated to is running in a pod on the same cluster and
+the service-DNS is used as the remote's URL (e.g. http://gerrit-replica-git-backend-service:80/git/${name}.git),
+a podSelector (and namespaceSelector, if the pod is running in a different
+namespace) can be used to whitelist the traffic:
+
+```yaml
+gerrit:
+ networkPolicy:
+ egress:
+ - to:
+ - podSelector:
+ matchLabels:
+ app: git-backend
+```
+
+If the remote is outside the cluster, the IP of the remote or its load balancer
+can also be whitelisted, e.g.:
+
+```yaml
+gerrit:
+ networkPolicy:
+ egress:
+ - to:
+ - ipBlock:
+ cidr: xxx.xxx.0.0/16
+```
+
+The same principle also applies to other use cases, e.g. connecting to a database.
+For more information about the NetworkPolicy resource refer to the
+[Kubernetes documentation](https://kubernetes.io/docs/concepts/services-networking/network-policies/).
+
+### Workaround for NFS
+
+Kubernetes will not always be able to adapt the ownership of the files within NFS
+volumes. Thus, a workaround exists that will add init-containers to
+adapt file ownership. Note, that only the ownership of the root directory of the
+volume will be changed. All data contained within will be expected to already be
+owned by the user used by Gerrit. Also the ID-domain will be configured to ensure
+correct ID-mapping.
+
+| Parameter | Description | Default |
+|-----------|-------------|---------|
+| `nfsWorkaround.enabled` | Whether the volume used is an NFS-volume | `false` |
+| `nfsWorkaround.chownOnStartup` | Whether to chown the volume on pod startup | `false` |
+| `nfsWorkaround.idDomain` | The ID-domain that should be used to map user-/group-IDs for the NFS mount | `localdomain.com` |
+
+### Storage for Git repositories
+
+| Parameter | Description | Default |
+|-----------|-------------|---------|
+| `gitRepositoryStorage.externalPVC.use` | Whether to use a PVC deployed outside the chart | `false` |
+| `gitRepositoryStorage.externalPVC.name` | Name of the external PVC | `git-repositories-pvc` |
+| `gitRepositoryStorage.size` | Size of the volume storing the Git repositories | `5Gi` |
+
+If the git repositories should be persisted even if the chart is deleted and in
+a way that the volume containing them can be mounted by the reinstalled chart,
+the PVC claiming the volume has to be created independently of the chart. To use
+the external PVC, set `gitRepositoryStorage.externalPVC.enabled` to `true` and
+give the name of the PVC under `gitRepositoryStorage.externalPVC.name`.
+
+### Storage for Logs
+
+The logs can be stored in a dedicated persistent volume. This volume has to be a
+read-write-many volume to be able to be used by multiple pods.
+
+| Parameter | Description | Default |
+|-----------|-------------|---------|
+| `logStorage.enabled` | Whether to enable persistence of logs | `false` |
+| `logStorage.externalPVC.use` | Whether to use a PVC deployed outside the chart | `false` |
+| `logStorage.externalPVC.name` | Name of the external PVC | `gerrit-logs-pvc` |
+| `logStorage.size` | Size of the volume | `5Gi` |
+| `logStorage.cleanup.enabled` | Whether to regularly delete old logs | `false` |
+| `logStorage.cleanup.schedule` | Cron schedule defining when to run the cleanup job | `0 0 * * *` |
+| `logStorage.cleanup.retentionDays` | Number of days to retain the logs | `14` |
+| `logStorage.cleanup.resources` | Resources the container is allowed to use | `requests.cpu: 100m` |
+| `logStorage.cleanup.additionalPodLabels` | Additional labels for pods | `{}` |
+| | | `requests.memory: 256Mi` |
+| | | `limits.cpu: 100m` |
+| | | `limits.memory: 256Mi` |
+
+Each pod will create a separate folder for its logs, allowing to trace logs to
+the respective pods.
+
+### CA certificate
+
+Some application may require TLS verification. If the default CA built into the
+containers is not enough a custom CA certificate can be given to the deployment.
+Note, that Gerrit will require its CA in a JKS keytore, which is described below.
+
+| Parameter | Description | Default |
+|-----------|-------------|---------|
+| `caCert` | CA certificate for TLS verification (if not set, the default will be used) | `None` |
+
+### Ingress
+
+| Parameter | Description | Default |
+|-----------|-------------|---------|
+| `ingress.enabled` | Whether to enable the Ingress | `false` |
+| `ingress.host` | REQUIRED: Host name to use for the Ingress (required for Ingress) | `nil` |
+| `ingress.additionalAnnotations` | Additional annotations for the Ingress | `nil` |
+| `ingress.tls.enabled` | Whether to enable TLS termination in the Ingress | `false` |
+| `ingress.tls.secret.create` | Whether to create a TLS-secret | `true` |
+| `ingress.tls.secret.name` | Name of an external secret that will be used as a TLS-secret | `nil` |
+| `ingress.tls.cert` | Public SSL server certificate | `-----BEGIN CERTIFICATE-----` |
+| `ingress.tls.key` | Private SSL server certificate | `-----BEGIN RSA PRIVATE KEY-----` |
+
+***note
+For graceful shutdown to work with an ingress, the ingress controller has to be
+configured to gracefully close the connections as well.
+***
+
+### Git garbage collection
+
+| Parameter | Description | Default |
+|-----------|-------------|---------|
+| `gitGC.image` | Image name of the Git-GC container image | `k8sgerrit/git-gc` |
+| `gitGC.schedule` | Cron-formatted schedule with which to run Git garbage collection | `0 6,18 * * *` |
+| `gitGC.resources` | Configure the amount of resources the pod requests/is allowed | `requests.cpu: 100m` |
+| | | `requests.memory: 256Mi` |
+| | | `limits.cpu: 100m` |
+| | | `limits.memory: 256Mi` |
+| `gitGC.logging.persistence.enabled` | Whether to persist logs | `true` |
+| `gitGC.logging.persistence.size` | Storage size for persisted logs | `1Gi` |
+| `gitGC.tolerations` | Taints and tolerations work together to ensure that pods are not scheduled onto inappropriate nodes. For more information, please refer to the following documents. [Taints and Tolerations](https://kubernetes.io/docs/concepts/scheduling-eviction/taint-and-toleration) | [] |
+| `gitGC.nodeSelector` | Assigns a Pod to the specified Nodes. For more information, please refer to the following documents. [Assign Pods to Nodes](https://kubernetes.io/docs/tasks/configure-pod-container/assign-pods-nodes/). [Assigning Pods to Nodes](https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/) | {} |
+| `gitGC.affinity` | Assigns a Pod to the specified Nodes. For more information, please refer to the following documents. [Assign Pods to Nodes using Node Affinity](https://kubernetes.io/docs/tasks/configure-pod-container/assign-pods-nodes-using-node-affinity/). [Assigning Pods to Nodes](https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/) | {} |
+| `gitGC.additionalPodLabels` | Additional labels for Pods | `{}` |
+
+### Gerrit
+
+***note
+The way the Jetty servlet used by Gerrit works, the Gerrit component of the
+gerrit chart actually requires the URL to be known, when the chart is installed.
+The suggested way to do that is to use the provided Ingress resource. This requires
+that a URL is available and that the DNS is configured to point the URL to the
+IP of the node the Ingress controller is running on!
+***
+
+***note
+Setting the canonical web URL in the gerrit.config to the host used for the Ingress
+is mandatory, if access to Gerrit is required!
+***
+
+***note
+While the chart allows to configure multiple replica for the Gerrit StatefulSet,
+scaling of Gerrit is currently not supported, since no mechanism to guarantee a
+consistent state is currently in place. This is planned to be implemented in the
+future.
+***
+
+| Parameter | Description | Default |
+|-----------|-------------|---------|
+| `gerrit.images.gerritInit` | Image name of the Gerrit init container image | `k8sgerrit/gerrit-init` |
+| `gerrit.images.gerrit` | Image name of the Gerrit container image | `k8sgerrit/gerrit` |
+| `gerrit.tolerations` | Taints and tolerations work together to ensure that pods are not scheduled onto inappropriate nodes. For more information, please refer to the following documents. [Taints and Tolerations](https://kubernetes.io/docs/concepts/scheduling-eviction/taint-and-toleration) | [] |
+| `gerrit.topologySpreadConstraints` | Control how Pods are spread across your cluster among failure-domains. For more information, please refer to the following documents. [Pod Topology Spread Constraints](https://kubernetes.io/docs/concepts/workloads/pods/pod-topology-spread-constraints) | {} |
+| `gerrit.nodeSelector` | Assigns a Pod to the specified Nodes. For more information, please refer to the following documents. [Assign Pods to Nodes](https://kubernetes.io/docs/tasks/configure-pod-container/assign-pods-nodes/). [Assigning Pods to Nodes](https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/) | {} |
+| `gerrit.affinity` | Assigns a Pod to the specified Nodes. For more information, please refer to the following documents. [Assign Pods to Nodes using Node Affinity](https://kubernetes.io/docs/tasks/configure-pod-container/assign-pods-nodes-using-node-affinity/). [Assigning Pods to Nodes](https://kubernetes.io/docs/concepts/scheduling-eviction/assign-pod-node/) | {} |
+| `gerrit.additionalAnnotations` | Additional annotations for the Pods | {} |
+| `gerrit.additionalPodLabels` | Additional labels for Pods | `{}` |
+| `gerrit.replicas` | Number of replica pods to deploy | `1` |
+| `gerrit.updatePartition` | Ordinal at which to start updating pods. Pods with a lower ordinal will not be updated. | `0` |
+| `gerrit.resources` | Configure the amount of resources the pod requests/is allowed | `requests.cpu: 1` |
+| | | `requests.memory: 5Gi` |
+| | | `limits.cpu: 1` |
+| | | `limits.memory: 6Gi` |
+| `gerrit.persistence.enabled` | Whether to persist the Gerrit site | `true` |
+| `gerrit.persistence.size` | Storage size for persisted Gerrit site | `10Gi` |
+| `gerrit.livenessProbe` | Configuration of the liveness probe timings | `{initialDelaySeconds: 30, periodSeconds: 5}` |
+| `gerrit.readinessProbe` | Configuration of the readiness probe timings | `{initialDelaySeconds: 5, periodSeconds: 1}` |
+| `gerrit.startupProbe` | Configuration of the startup probe timings | `{initialDelaySeconds: 10, periodSeconds: 5}` |
+| `gerrit.gracefulStopTimeout` | Time in seconds Kubernetes will wait until killing the pod during termination (has to be longer then Gerrit's httpd.gracefulStopTimeout to allow graceful shutdown of Gerrit) | `90` |
+| `gerrit.networkPolicy.ingress` | Custom ingress-network policy for gerrit pods | `nil` |
+| `gerrit.networkPolicy.egress` | Custom egress-network policy for gerrit pods | `nil` |
+| `gerrit.service.additionalAnnotations` | Additional annotations for the Service | `{}` |
+| `gerrit.service.loadBalancerSourceRanges` | The list of allowed IPs for the Service | `[]` |
+| `gerrit.service.type` | Which kind of Service to deploy | `NodePort` |
+| `gerrit.service.externalTrafficPolicy` | Specify how traffic from external is handled | `Cluster` |
+| `gerrit.service.http.port` | Port over which to expose HTTP | `80` |
+| `gerrit.service.ssh.enabled` | Whether to enable SSH | `false` |
+| `gerrit.service.ssh.port` | Port over which to expose SSH | `29418` |
+| `gerrit.keystore` | base64-encoded Java keystore (`cat keystore.jks \| base64`) to be used by Gerrit, when using SSL | `nil` |
+| `gerrit.index.type` | Index type used by Gerrit (either `lucene` or `elasticsearch`) | `lucene` |
+| `gerrit.pluginManagement.plugins` | List of Gerrit plugins to install | `[]` |
+| `gerrit.pluginManagement.plugins[0].name` | Name of plugin | `nil` |
+| `gerrit.pluginManagement.plugins[0].url` | Download url of plugin. If given the plugin will be downloaded, otherwise it will be installed from the gerrit.war-file. | `nil` |
+| `gerrit.pluginManagement.plugins[0].sha1` | SHA1 sum of plugin jar used to ensure file integrity and version (optional) | `nil` |
+| `gerrit.pluginManagement.plugins[0].installAsLibrary` | Whether the plugin should be symlinked to the lib-dir in the Gerrit site. | `nil` |
+| `gerrit.pluginManagement.libs` | List of Gerrit library modules to install | `[]` |
+| `gerrit.pluginManagement.libs[0].name` | Name of the lib module | `nil` |
+| `gerrit.pluginManagement.libs[0].url` | Download url of lib module. | `nil` |
+| `gerrit.pluginManagement.libs[0].sha1` | SHA1 sum of plugin jar used to ensure file integrity and version | `nil` |
+| `gerrit.pluginManagement.cache.enabled` | Whether to cache downloaded plugins | `false` |
+| `gerrit.pluginManagement.cache.size` | Size of the volume used to store cached plugins | `1Gi` |
+| `gerrit.priorityClassName` | Name of the PriorityClass to apply to the master pod | `nil` |
+| `gerrit.etc.config` | Map of config files (e.g. `gerrit.config`) that will be mounted to `$GERRIT_SITE/etc`by a ConfigMap | `{gerrit.config: ..., replication.config: ...}`[see here](#Gerrit-config-files) |
+| `gerrit.etc.secret` | Map of config files (e.g. `secure.config`) that will be mounted to `$GERRIT_SITE/etc`by a Secret | `{secure.config: ...}` [see here](#Gerrit-config-files) |
+| `gerrit.additionalConfigMaps` | Allows to mount additional ConfigMaps into a subdirectory of `$SITE/data` | `[]` |
+| `gerrit.additionalConfigMaps[*].name` | Name of the ConfigMap | `nil` |
+| `gerrit.additionalConfigMaps[*].subDir` | Subdirectory under `$SITE/data` into which the files should be symlinked | `nil` |
+| `gerrit.additionalConfigMaps[*].data` | Data of the ConfigMap. If not set, ConfigMap has to be created manually | `nil` |
+
+### Gerrit config files
+
+The gerrit chart provides a ConfigMap containing the configuration files
+used by Gerrit, e.g. `gerrit.config` and a Secret containing sensitive configuration
+like the `secure.config` to configure the Gerrit installation in the Gerrit
+component. The content of the config files can be set in the `values.yaml` under
+the keys `gerrit.etc.config` and `gerrit.etc.secret` respectively.
+The key has to be the filename (eg. `gerrit.config`) and the file's contents
+the value. This way an arbitrary number of configuration files can be loaded into
+the `$GERRIT_SITE/etc`-directory, e.g. for plugins.
+All configuration options for Gerrit are described in detail in the
+[official documentation of Gerrit](https://gerrit-review.googlesource.com/Documentation/config-gerrit.html).
+Some options however have to be set in a specified way for Gerrit to work as
+intended with the chart:
+
+- `gerrit.basePath`
+
+ Path to the directory containing the repositories. The chart mounts this
+ directory from a persistent volume to `/var/gerrit/git` in the container. For
+ Gerrit to find the correct directory, this has to be set to `git`.
+
+- `gerrit.serverId`
+
+ In Gerrit-version higher than 2.14 Gerrit needs a server ID, which is used by
+ NoteDB. Gerrit would usually generate a random ID on startup, but since the
+ gerrit.config file is read only, when mounted as a ConfigMap this fails.
+ Thus the server ID has to be set manually!
+
+- `gerrit.canonicalWebUrl`
+
+ The canonical web URL has to be set to the Ingress host.
+
+- `httpd.listenURL`
+
+ This has to be set to `proxy-http://*:8080/` or `proxy-https://*:8080`,
+ depending of TLS is enabled in the Ingress or not, otherwise the Jetty
+ servlet will run into an endless redirect loop.
+
+- `httpd.gracefulStopTimeout` / `sshd.gracefulStopTimeout`
+
+ To enable graceful shutdown of the embedded jetty server and SSHD, a timeout
+ has to be set with this option. This will be the maximum time, Gerrit will wait
+ for HTTP requests to finish before shutdown.
+
+- `container.user`
+
+ The technical user in the Gerrit container is called `gerrit`. Thus, this
+ value is required to be `gerrit`.
+
+- `container.javaHome`
+
+ This has to be set to `/usr/lib/jvm/java-11-openjdk-amd64`, since this is
+ the path of the Java installation in the container.
+
+- `container.javaOptions`
+
+ The maximum heap size has to be set. And its value has to be lower than the
+ memory resource limit set for the container (e.g. `-Xmx4g`). In your calculation,
+ allow memory for other components running in the container.
+
+To enable liveness- and readiness probes, the healthcheck plugin will be installed
+by default. Note, that by configuring to use a packaged or downloaded version of
+the healthcheck plugin, the configured version will take precedence over the default
+version. The plugin is by default configured to disable the `querychanges` and
+`auth` healthchecks, since these would not work on a new and empty Gerrit server.
+The default configuration can be overwritten by adding the `healthcheck.config`
+file as a key-value pair to `gerrit.etc.config` as for every other configuration.
+
+SSH keys should be configured via the helm-chart using the `gerrit.etc.secret`
+map. Gerrit will create its own keys, if none are present in the site, but if
+multiple Gerrit pods are running, each Gerrit instance would have its own keys.
+Users accessing Gerrit via a load balancer would get issues due to changing
+host keys.
+
+### Installing Gerrit plugins
+
+There are several different ways to install plugins for Gerrit:
+
+- **RECOMMENDED: Package the plugins to install into the WAR-file containing Gerrit.**
+ This method provides the most stable way to install plugins, but requires to
+ use a custom built gerrit-war file and container images, if plugins are required
+ that are not part of the official `release.war`-file.
+
+- **Download and cache plugins.** The chart supports downloading the plugin files and
+ to cache them in a separate volume, that is shared between Gerrit-pods. SHA1-
+ sums are used to validate plugin-files and versions.
+
+- **Download plugins, but do not cache them.** This should only be used during
+ development to save resources (the shared volume). Each pod will download the
+ plugin-files on its own. Pods will fail to start up, if the download-URL is
+ not valid anymore at some point in time.
+
+## Upgrading the Chart
+
+To upgrade an existing installation of the gerrit chart, e.g. to install
+a newer chart version or to use an updated custom `values.yaml`-file, execute
+the following command:
+
+```sh
+cd $(git rev-parse --show-toplevel)/helm-charts
+helm upgrade \
+ <release-name> \
+ ./gerrit \ # path to chart
+ -f <path-to-custom-values>.yaml
+```
+
+## Uninstalling the Chart
+
+To delete the chart from the cluster, use:
+
+```sh
+helm delete <release-name>
+```