Using the GitLab Shell chart

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The gitlab-shell sub-chart provides an SSH server configured for Git SSH access to GitLab.

Requirements

This chart depends on access to the Workhorse services, either as part of the complete GitLab chart or provided as an external service reachable from the Kubernetes cluster this chart is deployed onto.

Design Choices

In order to easily support SSH replicas, and avoid using shared storage for the SSH authorized keys, we are using the SSH AuthorizedKeysCommand to authenticate against the GitLab authorized keys endpoint. As a result, we don’t persist or update the AuthorizedKeys file within these pods.

Configuration

The gitlab-shell chart is configured in two parts: external services, and chart settings. The port exposed through Ingress is configured with global.shell.port, and defaults to 22. The Service’s external port is also controlled by global.shell.port.

Installation command line options

Parameter Default Description
affinity {} Affinity rules for pod assignment
annotations   Pod annotations
podLabels   Supplemental Pod labels. Will not be used for selectors.
common.labels   Supplemental labels that are applied to all objects created by this chart.
config.clientAliveInterval 0 Interval between keepalive pings on otherwise idle connections; the default value of 0 disables this ping
config.loginGraceTime 60 Specifies amount of time that the server will disconnect after if the user has not successfully logged in
config.maxStartups.full 100 SSHd refuse probability will increase linearly and all unauthenticated connection attempts would be refused when unauthenticated connections number will reach specified number
config.maxStartups.rate 30 SSHd will refuse connections with specified probability when there would be too many unauthenticated connections (optional)
config.maxStartups.start 10 SSHd will refuse connection attempts with some probability if there are currently more than the specified number of unauthenticated connections (optional)
config.proxyProtocol false Enable PROXY protocol support for the gitlab-sshd daemon
config.proxyPolicy "use" Specify policy for handling PROXY protocol. Value must be one of use, require, ignore, reject
config.proxyHeaderTimeout "500ms" The maximum duration gitlab-sshd will wait before giving up on reading the PROXY protocol header. Must include units: ms, s, or m.
config.ciphers [aes128-gcm@openssh.com, chacha20-poly1305@openssh.com, aes256-gcm@openssh.com, aes128-ctr, aes192-ctr, aes256-ctr] Specify the ciphers allowed.
config.kexAlgorithms [curve25519-sha256, curve25519-sha256@libssh.org, ecdh-sha2-nistp256, ecdh-sha2-nistp384, ecdh-sha2-nistp521, diffie-hellman-group14-sha256, diffie-hellman-group14-sha1] Specifies the available KEX (Key Exchange) algorithms.
config.macs [hmac-sha2-256-etm@openssh.com, hmac-sha2-512-etm@openssh.com, hmac-sha2-256, hmac-sha2-512, hmac-sha1] Specifies the available MAC (message authentication code algorithms.
config.publicKeyAlgorithms [] Custom list of public key algorithms. If empty, the default algorithms are used.
config.gssapi.enabled false Enable GSS-API support for the gitlab-sshd daemon
config.gssapi.keytab.secret   The name of a Kubernetes secret holding the keytab for the gssapi-with-mic authentication method
config.gssapi.keytab.key keytab Key holding the keytab in the Kubernetes secret
config.gssapi.krb5Config   Content of the /etc/krb5.conf file in the GitLab Shell container
config.gssapi.servicePrincipalName   The Kerberos service name to be used by the gitlab-sshd daemon
config.lfs.pureSSHProtocol false Enable LFS Pure SSH protocol support
opensshd.supplemental_config   Supplemental configuration, appended to sshd_config. Strict alignment to man page
deployment.livenessProbe.initialDelaySeconds 10 Delay before liveness probe is initiated
deployment.livenessProbe.periodSeconds 10 How often to perform the liveness probe
deployment.livenessProbe.timeoutSeconds 3 When the liveness probe times out
deployment.livenessProbe.successThreshold 1 Minimum consecutive successes for the liveness probe to be considered successful after having failed
deployment.livenessProbe.failureThreshold 3 Minimum consecutive failures for the liveness probe to be considered failed after having succeeded
deployment.readinessProbe.initialDelaySeconds 10 Delay before readiness probe is initiated
deployment.readinessProbe.periodSeconds 5 How often to perform the readiness probe
deployment.readinessProbe.timeoutSeconds 3 When the readiness probe times out
deployment.readinessProbe.successThreshold 1 Minimum consecutive successes for the readiness probe to be considered successful after having failed
deployment.readinessProbe.failureThreshold 2 Minimum consecutive failures for the readiness probe to be considered failed after having succeeded
deployment.strategy {} Allows one to configure the update strategy utilized by the deployment
deployment.terminationGracePeriodSeconds 30 Seconds that Kubernetes will wait for a pod to forcibly exit
enabled true Shell enable flag
extraContainers   List of extra containers to include
extraInitContainers   List of extra init containers to include
extraVolumeMounts   List of extra volumes mounts to do
extraVolumes   List of extra volumes to create
extraEnv   List of extra environment variables to expose
extraEnvFrom   List of extra environment variables from other data sources to expose
hpa.behavior {scaleDown: {stabilizationWindowSeconds: 300 }} Behavior contains the specifications for up- and downscaling behavior (requires autoscaling/v2beta2 or higher)
hpa.customMetrics [] Custom metrics contains the specifications for which to use to calculate the desired replica count (overrides the default use of Average CPU Utilization configured in targetAverageUtilization)
hpa.cpu.targetType AverageValue Set the autoscaling CPU target type, must be either Utilization or AverageValue
hpa.cpu.targetAverageValue 100m Set the autoscaling CPU target value
hpa.cpu.targetAverageUtilization   Set the autoscaling CPU target utilization
hpa.memory.targetType   Set the autoscaling memory target type, must be either Utilization or AverageValue
hpa.memory.targetAverageValue   Set the autoscaling memory target value
hpa.memory.targetAverageUtilization   Set the autoscaling memory target utilization
hpa.targetAverageValue   DEPRECATED Set the autoscaling CPU target value
image.pullPolicy IfNotPresent Shell image pull policy
image.pullSecrets   Secrets for the image repository
image.repository registry.gitlab.com/gitlab-org/build/cng/gitlab-shell Shell image repository
image.tag master Shell image tag
init.image.repository   initContainer image
init.image.tag   initContainer image tag
init.containerSecurityContext   initContainer specific securityContext
init.containerSecurityContext.allowPrivilegeEscalation false initContainer specific: Controls whether a process can gain more privileges than its parent process
init.containerSecurityContext.runAsNonRoot true initContainer specific: Controls whether the container runs with a non-root user
init.containerSecurityContext.capabilities.drop [ "ALL" ] initContainer specific: Removes Linux capabilities for the container
keda.enabled false Use KEDA ScaledObjects instead of HorizontalPodAutoscalers
keda.pollingInterval 30 The interval to check each trigger on
keda.cooldownPeriod 300 The period to wait after the last trigger reported active before scaling the resource back to 0
keda.minReplicaCount   Minimum number of replicas KEDA will scale the resource down to, defaults to minReplicas
keda.maxReplicaCount   Maximum number of replicas KEDA will scale the resource up to, defaults to maxReplicas
keda.fallback   KEDA fallback configuration, see the documentation
keda.hpaName   The name of the HPA resource KEDA will create, defaults to keda-hpa-{scaled-object-name}
keda.restoreToOriginalReplicaCount   Specifies whether the target resource should be scaled back to original replicas count after the ScaledObject is deleted
keda.behavior   The specifications for up- and downscaling behavior, defaults to hpa.behavior
keda.triggers   List of triggers to activate scaling of the target resource, defaults to triggers computed from hpa.cpu and hpa.memory
logging.format json Set to text for unstructured logs
logging.sshdLogLevel ERROR Log level for underlying SSH daemon
priorityClassName   Priority class assigned to pods.
replicaCount 1 Shell replicas
serviceLabels {} Supplemental service labels
service.allocateLoadBalancerNodePorts Not set, to use Kubernetes default value. Allows to disable NodePort allocation on LoadBalancer service, see the documentation
service.externalTrafficPolicy Cluster Shell service external traffic policy (Cluster or Local)
service.internalPort 2222 Shell internal port
service.nodePort   Sets shell nodePort if set
service.name gitlab-shell Shell service name
service.type ClusterIP Shell service type
service.loadBalancerIP   IP address to assign to LoadBalancer (if supported)
service.loadBalancerSourceRanges   List of IP CIDRs allowed access to LoadBalancer (if supported)
serviceAccount.annotations {} ServiceAccount annotations
serviceAccount.automountServiceAccountToken false Indicates whether or not the default ServiceAccount access token should be mounted in pods
serviceAccount.create false Indicates whether or not a ServiceAccount should be created
serviceAccount.enabled false Indicates whether or not to use a ServiceAccount
serviceAccount.name   Name of the ServiceAccount. If not set, the full chart name is used
securityContext.fsGroup 1000 Group ID under which the pod should be started
securityContext.runAsUser 1000 User ID under which the pod should be started
securityContext.fsGroupChangePolicy   Policy for changing ownership and permission of the volume (requires Kubernetes 1.23)
securityContext.seccompProfile.type RuntimeDefault Seccomp profile to use
containerSecurityContext   Override container securityContext under which the container is started
containerSecurityContext.runAsUser 1000 Allow to overwrite the specific security context under which the container is started
containerSecurityContext.allowPrivilegeEscalation false Controls whether a process of the container can gain more privileges than its parent process
containerSecurityContext.runAsNonRoot true Controls whether the container runs with a non-root user
containerSecurityContext.capabilities.drop [ "ALL" ] Removes Linux capabilities for the Gitaly container
sshDaemon openssh Selects which SSH daemon would be run, possible values (openssh, gitlab-sshd)
tolerations [] Toleration labels for pod assignment
traefik.entrypoint gitlab-shell When using traefik, which traefik entrypoint to use for GitLab Shell. Defaults to gitlab-shell
traefik.tcpMiddlewares [] When using traefik, which TCP Middlewares to add to IngressRouteTCP resource. No middlewares by default
workhorse.serviceName webservice Workhorse service name (by default, Workhorse is a part of the webservice Pods / Service)
metrics.enabled false If a metrics endpoint should be made available for scraping (requires sshDaemon=gitlab-sshd).
metrics.port 9122 Metrics endpoint port
metrics.path /metrics Metrics endpoint path
metrics.serviceMonitor.enabled false If a ServiceMonitor should be created to enable Prometheus Operator to manage the metrics scraping, note that enabling this removes the prometheus.io scrape annotations
metrics.serviceMonitor.additionalLabels {} Additional labels to add to the ServiceMonitor
metrics.serviceMonitor.endpointConfig {} Additional endpoint configuration for the ServiceMonitor
metrics.annotations   DEPRECATED Set explicit metrics annotations. Replaced by template content.

Chart configuration examples

extraEnv

extraEnv allows you to expose additional environment variables in all containers in the pods.

Below is an example use of extraEnv:

extraEnv:
  SOME_KEY: some_value
  SOME_OTHER_KEY: some_other_value

When the container is started, you can confirm that the environment variables are exposed:

env | grep SOME
SOME_KEY=some_value
SOME_OTHER_KEY=some_other_value

extraEnvFrom

extraEnvFrom allows you to expose additional environment variables from other data sources in all containers in the pods.

Below is an example use of extraEnvFrom:

extraEnvFrom:
  MY_NODE_NAME:
    fieldRef:
      fieldPath: spec.nodeName
  MY_CPU_REQUEST:
    resourceFieldRef:
      containerName: test-container
      resource: requests.cpu
  SECRET_THING:
    secretKeyRef:
      name: special-secret
      key: special_token
      # optional: boolean
  CONFIG_STRING:
    configMapKeyRef:
      name: useful-config
      key: some-string
      # optional: boolean

image.pullSecrets

pullSecrets allows you to authenticate to a private registry to pull images for a pod.

Additional details about private registries and their authentication methods can be found in the Kubernetes documentation.

Below is an example use of pullSecrets:

image:
  repository: my.shell.repository
  tag: latest
  pullPolicy: Always
  pullSecrets:
  - name: my-secret-name
  - name: my-secondary-secret-name

serviceAccount

This section controls if a ServiceAccount should be created and if the default access token should be mounted in pods.

Name Type Default Description
annotations Map {} ServiceAccount annotations.
automountServiceAccountToken Boolean false Controls if the default ServiceAccount access token should be mounted in pods. You should not enable this unless it is required by certain sidecars to work properly (for example, Istio).
create Boolean false Indicates whether or not a ServiceAccount should be created.
enabled Boolean false Indicates whether or not to use a ServiceAccount.
name String   Name of the ServiceAccount. If not set, the full chart name is used.

livenessProbe/readinessProbe

deployment.livenessProbe and deployment.readinessProbe provide a mechanism to help control the termination of Pods under some scenarios.

Larger repositories benefit from tuning liveness and readiness probe times to match their typical long-running connections. Set readiness probe duration shorter than liveness probe duration to minimize potential interruptions during clone and push operations. Increase terminationGracePeriodSeconds and give these operations more time before the scheduler terminates the pod. Consider the example below as a starting point to tune GitLab Shell pods for increased stability and efficiency with larger repository workloads.

deployment:
  livenessProbe:
    initialDelaySeconds: 10
    periodSeconds: 20
    timeoutSeconds: 3
    successThreshold: 1
    failureThreshold: 10
  readinessProbe:
    initialDelaySeconds: 10
    periodSeconds: 5
    timeoutSeconds: 2
    successThreshold: 1
    failureThreshold: 3
  terminationGracePeriodSeconds: 300

Reference the official Kubernetes Documentation for additional details regarding this configuration.

tolerations

tolerations allow you schedule pods on tainted worker nodes

Below is an example use of tolerations:

tolerations:
- key: "node_label"
  operator: "Equal"
  value: "true"
  effect: "NoSchedule"
- key: "node_label"
  operator: "Equal"
  value: "true"
  effect: "NoExecute"

affinity

For more information, see affinity.

annotations

annotations allows you to add annotations to the GitLab Shell pods.

Below is an example use of annotations

annotations:
  kubernetes.io/example-annotation: annotation-value

External Services

This chart should be attached the Workhorse service.

Workhorse

workhorse:
  host: workhorse.example.com
  serviceName: webservice
  port: 8181
Name Type Default Description
host String   The hostname of the Workhorse server. This can be omitted in lieu of serviceName.
port Integer 8181 The port on which to connect to the Workhorse server.
serviceName String webservice The name of the service which is operating the Workhorse server. By default, Workhorse is a part of the webservice Pods / Service. If this is present, and host is not, the chart will template the hostname of the service (and current .Release.Name) in place of the host value. This is convenient when using Workhorse as a part of the overall GitLab chart.

Chart settings

The following values are used to configure the GitLab Shell Pods.

hostKeys.secret

The name of the Kubernetes secret to grab the SSH host keys from. The keys in the secret must start with the key names ssh_host_ in order to be used by GitLab Shell.

authToken

GitLab Shell uses an Auth Token in its communication with Workhorse. Share the token with GitLab Shell and Workhorse using a shared Secret.

authToken:
 secret: gitlab-shell-secret
 key: secret
Name Type Default Description
authToken.key String   The name of the key in the above secret that contains the auth token.
authToken.secret String   The name of the Kubernetes Secret to pull from.

LoadBalancer Service

If the service.type is set to LoadBalancer, you can optionally specify service.loadBalancerIP to create the LoadBalancer with a user-specified IP (if your cloud provider supports it).

You can also optionally specify a list of service.loadBalancerSourceRanges to restrict the CIDR ranges that can access the LoadBalancer (if your cloud provider supports it).

Additional information about the LoadBalancer service type can be found in the Kubernetes documentation

service:
  type: LoadBalancer
  loadBalancerIP: 1.2.3.4
  loadBalancerSourceRanges:
  - 5.6.7.8/32
  - 10.0.0.0/8

OpenSSH supplemental configuration

When making use of OpenSSH’s sshd (via .sshDaemon: openssh), it is possible to provide supplemental configuration in two ways: .opensshd.supplemental_config, and via mounting configuration snippets to /etc/ssh/sshd_config.d/*.conf.

Any configuration supplied must meet the functional requirements of sshd_config. Ensure you read the manual page.

opensshd.supplemental_config

The content of .opensshd.supplemental_config will be directly placed at the end the sshd_config file within the container. This value should be a mutli-line string.

Example, enabling older clients using the ssh-rsa key exchange algorithms. Note that enabling deprecated algorithms, such as ssh-rsa, creates significant security vulnerabilities. The likelihood of exploitation is significantly amplified on publicly exposed GitLab instances with these changes.

opensshd:
    supplemental_config: |-
      HostKeyAlgorithms +ssh-rsa,ssh-rsa-cert-v01@openssh.com
      PubkeyAcceptedAlgorithms +ssh-rsa,ssh-rsa-cert-v01@openssh.com
      CASignatureAlgorithms +ssh-rsa

sshd_config.d

You may provide full configuration snippets to sshd via mounting content into /etc/ssh/sshd_config.d, with the files matching *.conf. Note, that these are included after the default configuration which is required for the application to function in the container, and within the chart. These values will not override the contents of sshd_config, but extend them.

Example, mounting a single item of a ConfigMap into the container via extraVolumes and extraVolumeMounts:

extraVolumes: |
  - name: gitlab-sshdconfig-extra
    configMap:
      name: gitlab-sshdconfig-extra

extraVolumeMounts: |
  - name: gitlab-sshdconfig-extra
    mountPath: /etc/ssh/sshd_config.d/extra.conf
    subPath: extra.conf

Configuring the networkpolicy

This section controls the NetworkPolicy. This configuration is optional and is used to limit Egress and Ingress of the Pods to specific endpoints.

Name Type Default Description
enabled Boolean false This setting enables the NetworkPolicy
ingress.enabled Boolean false When set to true, the Ingress network policy will be activated. This will block all Ingress connections unless rules are specified.
ingress.rules Array [] Rules for the Ingress policy, for details see https://kubernetes.io/docs/concepts/services-networking/network-policies/#the-networkpolicy-resource and the example below
egress.enabled Boolean false When set to true, the Egress network policy will be activated. This will block all egress connections unless rules are specified.
egress.rules Array [] Rules for the egress policy, these for details see https://kubernetes.io/docs/concepts/services-networking/network-policies/#the-networkpolicy-resource and the example below

Example Network Policy

The gitlab-shell service requires Ingress connections for port 22 and Egress connections to various to default workhorse port 8181. This examples adds the following network policy:

  • All Ingress requests from the network on TCP 0.0.0.0/0 port 2222 are allowed
  • All Egress requests to the network on UDP 10.0.0.0/8 port 53 are allowed for DNS
  • All Egress requests to the network on TCP 10.0.0.0/8 port 8181 are allowed for Workhorse
  • All Egress requests to the network on TCP 10.0.0.0/8 port 8075 are allowed for Gitaly

Note the example provided is only an example and may not be complete

networkpolicy:
  enabled: true
  ingress:
    enabled: true
    rules:
      - from:
        - ipBlock:
            cidr: 0.0.0.0/0
        ports:
          - port: 2222
            protocol: TCP
  egress:
    enabled: true
    rules:
      - to:
        - ipBlock:
            cidr: 10.0.0.0/8
        ports:
          - port: 8181
            protocol: TCP
          - port: 8075
            protocol: TCP
          - port: 53
            protocol: UDP

Configuring KEDA

This keda section enables the installation of KEDA ScaledObjects instead of regular HorizontalPodAutoscalers. This configuration is optional and can be used when there is a need for autoscaling based on custom or external metrics.

Most settings default to the values set in the hpa section where applicable.

If the following are true, CPU and memory triggers are added automatically based on the CPU and memory thresholds set in the hpa section:

  • triggers is not set.
  • The corresponding request.cpu.request or request.memory.request setting is also set to a non-zero value.

If no triggers are set, the ScaledObject is not created.

Refer to the KEDA documentation for more details about those settings.

Name Type Default Description
enabled Boolean false Use KEDA ScaledObjects instead of HorizontalPodAutoscalers
pollingInterval Integer 30 The interval to check each trigger on
cooldownPeriod Integer 300 The period to wait after the last trigger reported active before scaling the resource back to 0
minReplicaCount Integer   Minimum number of replicas KEDA will scale the resource down to, defaults to minReplicas
maxReplicaCount Integer   Maximum number of replicas KEDA will scale the resource up to, defaults to maxReplicas
fallback Map   KEDA fallback configuration, see the documentation
hpaName String   The name of the HPA resource KEDA will create, defaults to keda-hpa-{scaled-object-name}
restoreToOriginalReplicaCount Boolean   Specifies whether the target resource should be scaled back to original replicas count after the ScaledObject is deleted
behavior Map   The specifications for up- and downscaling behavior, defaults to hpa.behavior
triggers Array   List of triggers to activate scaling of the target resource, defaults to triggers computed from hpa.cpu and hpa.memory

See examples/keda/gitlab-shell.yml for an usage example of keda.