Monitoring setup for Gerrit

This project provides a setup for monitoring Gerrit instances. The setup is based on Prometheus and Grafana running in Kubernetes. In addition, logging will be provided by Grafana Loki.

The setup is provided as a helm chart. It can be installed using Helm (This README expects Helm version 3.0 or higher).

The charts used in this setup are the chart provided in the open source and can be found on GitHub:

• Prometheus
• Grafana
• Loki

This project just provides values.yaml-files that are already configured to work with the metrics-reporter-prometheus-plugin of Gerrit to make the setup easier.

Dependencies

Software

• Gerrit
  Gerrit requires the following plugin to be installed:

  • metrics-reporter-prometheus

• Promtail
  Promtail has to be installed with access to the logs-directory in the Gerrit- site. A configuration-file for Promtail will be provided in this setup. Find the documentation for Promtail here

• Helm
  To install and configure Helm, follow the official guide.

• ytt
  ytt is a templating tool for yaml-files. It is required for some last moment configuration. Installation instructions can be found here.

• Pipenv
  Pipenv sets up a virtual python environment and installs required python packages based on a lock-file, ensuring a deterministic Python environment. Instruction on how Pipenv can be installed, can be found here

Infrastructure

• Kubernetes Cluster
  A cluster with at least 3 free CPUs and 4 GB of free memory are required. In addition persistent storage of about 30 GB will be used.

• Ingress Controller
  The charts currently expect a Nginx ingress controller to be installed in the cluster.

• Object store
  Loki will store the data chunks in an object store. This store has to be callable via the S3 API.

Add dashboards

To have dashboards deployed automatically during installation, export the dashboards to a JSON-file or create JSON-files describing the dashboards in another way. Put these dashboards into the ./dashboards-directory of this repository. During the installation the dashboards will be added to a configmap and with this automatically installed to Grafana.

Configuration

While this project is supposed to provide a specialized and opinionated monitoring setup, some configuration is highly dependent on the specific installation. These options have to be configured in the ./config.yaml before installing and are listed here:

option	description
gerritServers.[0].host	Hostname (incl. port, if required) of the Gerrit server to monitor
gerritServers.[0].username	Username of Gerrit user with 'View Metrics' capabilities
gerritServers.[0].password	Password of Gerrit user with 'View Metrics' capabilities
namespace	The namespace the charts are installed to
tls.skipVerify	Whether to skip TLS certificate verification
tls.caCert	CA certificate used for TLS certificate verification
promtail.storagePath	Path to directory, where Promtail is allowed to save files (e.g. positions.yaml)
promtail.logPath	Path to directory containing the Gerrit logs (e.g. /var/gerrit/logs)
prometheus.server.host	Prometheus server ingress hostname
prometheus.server.username	Username for Prometheus
prometheus.server.password	Password for Prometheus
prometheus.server.tls.cert	TLS certificate
prometheus.server.tls.key	TLS key
prometheus.alertmanager.slack.apiUrl	API URL of the Slack Webhook
prometheus.alertmanager.slack.channel	Channel to which the alerts should be posted
loki.host	Loki ingress hostname
loki.username	Username for Loki
loki.password	Password for Loki
loki.s3.protocol	Protocol used for communicating with S3
loki.s3.host	Hostname of the S3 object store
loki.s3.accessToken	The EC2 accessToken used for authentication with S3
loki.s3.secret	The secret associated with the accessToken
loki.s3.bucket	The name of the S3 bucket
loki.s3.region	The region in which the S3 bucket is hosted
loki.tls.cert	TLS certificate
loki.tls.key	TLS key
grafana.host	Grafana ingress hostname
grafana.tls.cert	TLS certificate
grafana.tls.key	TLS key
grafana.admin.username	Username for the admin user
grafana.admin.password	Password for the admin user
grafana.ldap.enabled	Whether to enable LDAP
grafana.ldap.host	Hostname of LDAP server
grafana.ldap.port	Port of LDAP server (Has to be quoted!)
grafana.ldap.password	Password of LDAP server
grafana.ldap.bind_dn	Bind DN (username) of the LDAP server
grafana.ldap.accountBases	List of base DNs to discover accounts (Has to have the format "['a', 'b']")
grafana.ldap.groupBases	List of base DNs to discover groups (Has to have the format "['a', 'b']")
grafana.dashboards.editable	Whether dashboards can be edited manually in the UI

Encryption

The configuration file contains secrets. Thus, to be able to share the configuration, e.g. with the CI-system, it is meant to be encrypted. The encryption is explained here.

The gerrit-monitoring.py install-command will decrypt the file before templating, if it was encrypted with sops.

Installation

Before using the script, set up a python environment using pipenv install.

The installation will use the environment of the current shell. Thus, make sure that the path for ytt, kubectland helm are set. Also the KUBECONFIG-variable has to be set to point to the kubeconfig of the target Kubernetes cluster.

This project provides a script to quickly install the monitoring setup. To use it, run:

pipenv run python ./gerrit-monitoring.py \
  --config config.yaml \
  install \
  [--output ./dist] \
  [--dryrun] \
  [--update-repo]

The command will use the given configuration (--config/-c) to create the final files in the directory given by --output/-o (default ./dist) and install/update the Kubernetes resources and charts, if the --dryrun/-d flag is not set. If the --update-repo-flag is used, the helm repository will be updated before installing the helm charts. This is for example required, if a chart version was updated.

Configure Promtail

Promtail has to be installed with access to the directory containing the Gerrit logs, e.g. on the same host. The installation as described above will create a configuration file for Promtail, which can be found in ./dist/promtail.yaml. Use it to configure Promtail by using the -config.file=./dist/promtail.yaml- parameter, when starting Promtail. Using the Promtail binary directly this would result in the following command:

$PATH_TO_PROMTAIL/promtail \
  -config.file=./dist/promtail.yaml \
  -client.external-labels=host=$(hostname)

The -client.external-labels=host=$(hostname) option will add a label to each job that contains the hostname. This is useful, if multiple host are scraped for logs and only one Grafana is used to view the logs.

If TLS-verification is activated, the CA-certificate used for verification (usually the one configured for tls.caCert) has to be present in the directory configured for promtail.storagePath in the config.yaml and has to be called promtail.ca.crt.

The Promtail configuration provided here expects the logs to be available in JSON-format. This can be configured by setting log.jsonLogging = true in the gerrit.config.

Uninstallation

To remove the Prometheus chart from the cluster, run

helm uninstall prometheus --namespace $NAMESPACE
helm uninstall loki --namespace $NAMESPACE
helm uninstall grafana --namespace $NAMESPACE
kubectl delete -f ./dist/configuration

To also release the volumes, run

kubectl delete -f ./dist/storage

NOTE: Doing so, all data, which was not backed up will be lost!

Remove the namespace:

kubectl delete -f ./dist/namespace.yaml

The ./gerrit-monitoring.py uninstall-script will automatically remove the charts installed in the configured namespace and delete the namespace as well:

pipenv run python ./gerrit-monitoring.py \
  --config config.yaml \
  uninstall