Gerrit is a web-based code review tool, which acts as a Git server. On large setups Gerrit servers can see a sizable amount of traffic from git operations performed by developers and build servers. The major part of requests are read-only requests (e.g. by git fetch operations). To take some load of the Gerrit server, Gerrit replicas can be deployed to serve read-only requests.
This helm chart provides a Gerrit replica setup that can be deployed on Kubernetes. The Gerrit replica is capable of receiving replicated git repositories from a Gerrit. The Gerrit replica can then serve authenticated read-only requests.
Helm (>= version 3.0)
(Check out this 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. This project was developed using the NFS-server-provisioner helm chart, a NFS-provisioner deployed in the Kubernetes cluster itself. Refer to this guide 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).
(Optional: Required, if SSL is configured) A Java keystore to be used by Gerrit.
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-replica, execute:
cd $(git rev-parse --show-toplevel)/helm-charts helm install \ gerrit-replica \ # release name ./gerrit-replica \ # path to chart -f <path-to-custom-values>.yaml
The command deploys the Gerrit replica on the current Kubernetes cluster. The configuration section lists the parameters that can be configured during installation.
The Gerrit replica requires the replicated All-Projects.git- and All-Users.git- repositories to be present in the /var/gerrit/git-directory. The gerrit-init- InitContainer will wait for this being the case. A way to do this is to access the Gerrit replica pod and to clone the repositories from the primary Gerrit (Make sure that you have the correct access rights do so.):
kubectl exec -it <gerrit-replica-pod> -c gerrit-init ash gerrit@<gerrit-replica-pod>:/var/tools$ cd /var/gerrit/git gerrit@<gerrit-replica-pod>:/var/gerrit/git$ git clone "http://gerrit.com/All-Projects" --mirror Cloning into bare repository 'All-Projects.git'... gerrit@<gerrit-replica-pod>:/var/gerrit/git$ git clone "http://gerrit.com/All-Users" --mirror Cloning into bare repository 'All-Users.git'...
The following sections list the configurable values in values.yaml. To configure a Gerrit replica 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.
In addition, single options can be set without creating a custom values.yaml:
cd $(git rev-parse --show-toplevel)/helm-charts helm install \ gerrit-replica \ # release name ./gerrit-replica \ # path to chart --set=gitRepositoryStorage.size=100Gi,gitBackend.replicas=2
| 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 | [] |
For information of how a StorageClass is configured in Kubernetes, read the official Documentation.
| 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.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 |
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 |
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 |
| 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 connecting to a database. On the other hand some defaults may be not restrictive enough. By default, the ingress traffic of the git-backend pod is not restricted. Thus, every source (with the right credentials) could push to the git-backend. To add an additional layer of security, the ingress rule could be defined more finegrained. The chart provides the possibility to define custom rules for ingress- traffic of the git-backend pod under gitBackend.networkPolicy.ingress. Depending on the scenario, there are different ways to restrict the incoming connections.
If the replicator (e.g. Gerrit) is running in a pod on the same cluster, a podSelector (and namespaceSelector, if the pod is running in a different namespace) can be used to whitelist the traffic:
gitBackend: networkPolicy: ingress: - from: - podSelector: matchLabels: app: gerrit
If the replicator is outside the cluster, the IP of the replicator can also be whitelisted, e.g.:
gitBackend: networkPolicy: ingress: - from: - 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.
| 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.
In addition to collecting logs with a log collection tool like Promtail, the logs can also be stored in a 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 |
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.
Istio can be used as an alternative to Kubernetes Ingresses to manage the traffic into the cluster and also inside the cluster. This requires istio to be installed beforehand. Some guidance on how to set up istio can be found here. The helm chart expects istio-injection to be enabled in the namespace, in which it will be installed.
In the case istio is used, all configuration for ingresses in the chart will be ignored.
| Parameter | Description | Default |
|---|---|---|
istio.enabled | Whether istio should be used (requires istio to be installed) | false |
istio.host | Hostname (CNAME must point to istio ingress gateway loadbalancer service) | nil |
istio.tls.enabled | Whether to enable TLS | false |
istio.tls.secret.create | Whether to create TLS certificate secret | true |
istio.tls.secret.name | Name of external secret containing TLS certificates | nil |
istio.tls.cert | TLS certificate | -----BEGIN CERTIFICATE----- |
istio.tls.key | TLS key | -----BEGIN RSA PRIVATE KEY----- |
istio.ssh.enabled | Whether to enable SSH | false |
As an alternative to istio the Nginx Ingress controller can be used to manage ingress traffic.
| Parameter | Description | Default |
|---|---|---|
ingress.enabled | Whether to deploy an Ingress | false |
ingress.host | Host name to use for the Ingress (required for Ingress) | nil |
ingress.maxBodySize | Maximum request body size allowed (Set to 0 for an unlimited request body size) | 50m |
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----- |
To collect Gerrit logs, a Promtail sidecar can be deployed into the Gerrit replica pods. This can for example be used together with the gerrit-monitoring project.
| Parameter | Description | Default |
|---|---|---|
promtailSidecar.enabled | Whether to install the Promatil sidecar container | false |
promtailSidecar.image | The promtail container image to use | grafana/promtail |
promtailSidecar.version | The promtail container image version | 1.3.0 |
promtailSidecar.resources | Configure the amount of resources the container requests/is allowed | requests.cpu: 100m |
requests.memory: 128Mi | ||
limits.cpu: 200m | ||
limits.memory: 128Mi | ||
promtailSidecar.tls.skipverify | Whether to skip TLS verification | true |
promtailSidecar.tls.caCert | CA certificate for TLS verification | -----BEGIN CERTIFICATE----- |
promtailSidecar.loki.url | URL to reach Loki | loki.example.com |
promtailSidecar.loki.user | Loki user | admin |
promtailSidecar.loki.password | Loki password | secret |
| Parameter | Description | Default |
|---|---|---|
gitBackend.image | Image name of the Apache-git-http-backend container image | k8sgerrit/apache-git-http-backend |
gitBackend.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 | [] |
gitBackend.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 | {} |
gitBackend.affinity | Assigns a Pod to the specified Nodes | podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].weight: 100 |
| podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.topologyKey: “topology.kubernetes.io/zone” | ||
| podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.labelSelector.matchExpressions[0].key: app | ||
| podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.labelSelector.matchExpressions[0].operator: In | ||
| podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.labelSelector.matchExpressions[0].values[0]: git-backend | ||
gitBackend.replicas | Number of pod replicas to deploy | 1 |
gitBackend.maxSurge | Max. percentage or number of pods allowed to be scheduled above the desired number | 25% |
gitBackend.maxUnavailable | Max. percentage or number of pods allowed to be unavailable at a time | 100% |
gitBackend.networkPolicy.ingress | Custom ingress-network policy for git-backend pods | [{}] (allow all) |
gitBackend.networkPolicy.egress | Custom egress-network policy for git-backend pods | nil |
gitBackend.resources | Configure the amount of resources the pod requests/is allowed | requests.cpu: 100m |
requests.memory: 256Mi | ||
limits.cpu: 100m | ||
limits.memory: 256Mi | ||
gitBackend.livenessProbe | Configuration of the liveness probe timings | {initialDelaySeconds: 10, periodSeconds: 5} |
gitBackend.readinessProbe | Configuration of the readiness probe timings | {initialDelaySeconds: 5, periodSeconds: 1} |
gitBackend.credentials.htpasswd | .htpasswd-file containing username/password-credentials for accessing git | git:$apr1$O/LbLKC7$Q60GWE7OcqSEMSfe/K8xU. (user: git, password: secret) |
gitBackend.service.type | Which kind of Service to deploy | LoadBalancer |
gitBackend.service.http.enabled | Whether to serve HTTP-requests (needed for Ingress) | true |
gitBackend.service.http.port | Port over which to expose HTTP | 80 |
gitBackend.service.https.enabled | Whether to serve HTTPS-requests | false |
gitBackend.service.https.port | Port over which to expose HTTPS | 443 |
Project creation, project deletion and HEAD update can also replicated. To enable this feature configure the replication plugin to use an adminUrl using the format gerrit+https://<apache-git-http-backend host>.
| 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.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 | [] |
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. Assigning Pods to Nodes | {} |
| Parameter | Description | Default |
|---|---|---|
gerritReplica.images.gerritInit | Image name of the Gerrit init container image | k8sgerrit/gerrit-init |
gerritReplica.images.gerritReplica | Image name of the Gerrit replica container image | k8sgerrit/gerrit |
gerritReplica.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 | [] |
gerritReplica.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 | {} |
gerritReplica.affinity | Assigns a Pod to the specified Nodes. By default, gerrit-replica is evenly distributed on topology.kubernetes.io/zone. For more information, please refer to the following documents. Assign Pods to Nodes using Node Affinity. Assigning Pods to Nodes | podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].weight: 100 |
| podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.topologyKey: “topology.kubernetes.io/zone” | ||
| podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.labelSelector.matchExpressions[0].key: app | ||
| podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.labelSelector.matchExpressions[0].operator: In | ||
| podAntiAffinity.preferredDuringSchedulingIgnoredDuringExecution[0].podAffinityTerm.labelSelector.matchExpressions[0].values[0]: gerrit-replica | ||
gerritReplica.replicas | Number of pod replicas to deploy | 1 |
gerritReplica.additionalAnnotations | Additional annotations for the Pods | {} |
gerritReplica.maxSurge | Max. percentage or number of pods allowed to be scheduled above the desired number | 25% |
gerritReplica.maxUnavailable | Max. percentage or number of pods allowed to be unavailable at a time | 100% |
gerritReplica.livenessProbe | Configuration of the liveness probe timings | {initialDelaySeconds: 60, periodSeconds: 5} |
gerritReplica.readinessProbe | Configuration of the readiness probe timings | {initialDelaySeconds: 10, periodSeconds: 10} |
gerritReplica.startupProbe | Configuration of the startup probe timings | {initialDelaySeconds: 10, periodSeconds: 5} |
gerritReplica.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 |
gerritReplica.resources | Configure the amount of resources the pod requests/is allowed | requests.cpu: 1 |
requests.memory: 5Gi | ||
limits.cpu: 1 | ||
limits.memory: 6Gi | ||
gerritReplica.networkPolicy.ingress | Custom ingress-network policy for gerrit-replica pods | nil |
gerritReplica.networkPolicy.egress | Custom egress-network policy for gerrit-replica pods | nil |
gerritReplica.service.type | Which kind of Service to deploy | NodePort |
gerritReplica.service.http.port | Port over which to expose HTTP | 80 |
gerritReplica.service.ssh.enabled | Whether to enable SSH for the Gerrit replica | false |
gerritReplica.service.ssh.port | Port for SSH | 29418 |
gerritReplica.keystore | base64-encoded Java keystore (`cat keystore.jks | base64`) to be used by Gerrit, when using SSL |
gerritReplica.plugins.packaged | List of Gerrit plugins that are packaged into the Gerrit-war-file to install | ["commit-message-length-validator", "download-commands", "replication", "reviewnotes"] |
gerritReplica.plugins.downloaded | List of Gerrit plugins that will be downloaded | nil |
gerritReplica.plugins.downloaded[0].name | Name of plugin | nil |
gerritReplica.plugins.downloaded[0].url | Download url of plugin | nil |
gerritReplica.plugins.downloaded[0].sha1 | SHA1 sum of plugin jar used to ensure file integrity and version (optional) | nil |
gerritReplica.plugins.installAsLibrary | List of plugins, which should be symlinked to the lib-dir in the Gerrit site (have to be in either ..downloaded or ..packaged) | [] |
gerritReplica.plugins.cache.enabled | Whether to cache downloaded plugins | false |
gerritReplica.plugins.cache.size | Size of the volume used to store cached plugins | 1Gi |
gerritReplica.priorityClassName | Name of the PriorityClass to apply to replica pods | nil |
gerritReplica.etc.config | Map of config files (e.g. gerrit.config) that will be mounted to $GERRIT_SITE/etcby a ConfigMap | {gerrit.config: ..., replication.config: ...}see here |
gerritReplica.etc.secret | Map of config files (e.g. secure.config) that will be mounted to $GERRIT_SITE/etcby a Secret | {secure.config: ...} see here |
gerritReplica.additionalConfigMaps | Allows to mount additional ConfigMaps into a subdirectory of $SITE/data | [] |
gerritReplica.additionalConfigMaps[*].name | Name of the ConfigMap | nil |
gerritReplica.additionalConfigMaps[*].subDir | Subdirectory under $SITE/data into which the files should be symlinked | nil |
gerritReplica.additionalConfigMaps[*].data | Data of the ConfigMap. If not set, secret has to be created manually | nil |
The gerrit-replica 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 gerritReplica.etc.config and gerritReplica.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. 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 replica container is called gerrit. Thus, this value is required to be gerrit.
container.replica
Since this chart is meant to install a Gerrit replica, this naturally has to be true.
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 the Gerrit replica does not index changes and a new Gerrit server will not yet necessarily have an user to validate authentication.
The default configuration can be overwritten by adding the healthcheck.config file as a key-value pair to gerritReplica.etc.config as for every other configuration.
SSH keys should be configured via the helm-chart using the gerritReplica.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.
To upgrade an existing installation of the gerrit-replica chart, e.g. to install a newer chart version or to use an updated custom values.yaml-file, execute the following command:
cd $(git rev-parse --show-toplevel)/helm-charts helm upgrade \ <release-name> \ ./gerrit-replica \ # path to chart -f <path-to-custom-values>.yaml \
To delete the chart from the cluster, use:
helm delete <release-name>