Install Scylla Monitoring Stack¶

Calculating Prometheus Minimal Disk Space requirement¶

Prometheus storage disk performance requirements: persistent block volume, for example an EC2 EBS volume

Prometheus storage disk volume requirement: proportional to the number of metrics it holds. The default retention period is 15 days, and the disk requirement is around 12MB per core per day, assuming the default scraping interval of 20s.

For example, when monitoring a 6 node Scylla cluster, each with 16 CPU cores (so a total of 96 cores), and using the default 15 days retention time, you will need minimal disk space for prometheus of

6 * 16 * 15 * 12MB ~ 16GB

To account for unexpected events, like replacing or adding nodes, we recommend allocating at least x2-3 space, in this case, ~50GB. Prometheus Storage disk does not have to be as fast as Scylla disk, and EC2 EBS, for example, is fast enough and provides HA out of the box.

Calculating Prometheus Minimal Memory Space requirement¶

Prometheus uses more memory when querying over a longer duration (e.g. looking at a dashboard on a week view would take more memory than on an hourly duration).

For Prometheus alone, you should have 60MB of memory per core in the cluster and it would use about 600MB of virtual memory per core. Because Prometheus is so memory demanding, it is a good idea to add swap, so queries with a longer duration would not crash the server.

Configure Scylla nodes from files¶

1. Create prometheus/scylla_servers.yml with the targets’ IPs (the servers you wish to monitor).

For example:

- targets:
      - 172.17.0.2
      - 172.17.0.3
  labels:
      cluster: cluster1
      dc: dc1

Using IPV6

To use IPv6 inside scylla_server.yml, add the IPv6 addresses with their square brackets and the port numbers.

For example:

- targets:
      - "[2600:1f18:26b1:3a00:fac8:118e:9199:67b9]:9180"
      - "[2600:1f18:26b1:3a00:fac8:118e:9199:67ba]:9180"
  labels:
      cluster: cluster1
      dc: dc1

For general node information (disk, network, etc.) Scylla Monitoring Stack uses the node_exporter agent that runs on the same machine as Scylla does. By default, Prometheus will assume you have a node_exporter running on each machine. If this is not the case, for example if Scylla runs in a container and the node_exporter runs on the host, you can override the node_exporter targets configuration file by creating an additional file and passing it with the -n flag.

If needed, you can set your own target file instead of the default prometheus/scylla_servers.yml, using the -s for Scylla target files.

For example:

./start-all.sh -s my_scylla_server.yml -d prometheus_data

Mark the different Data Centers with Labels.

As can be seen in the examples, each target has its own set of labels to mark the cluster name and the data center (dc). You can add multiple targets in the same file for multiple clusters or multiple data centers.

You can use the genconfig.py script to generate the server file. For example:

./genconfig.py -d myconf -dc dc1:192.168.0.1,192.168.0.2 -dc dc2:192.168.0.3,192.168.0.4

This will generate a server file for four servers in two datacenters server 192.168.0.1 and 192.168.0.2 in dc1 and 192.168.0.3 and 192.168.0.4 in dc2.

OR

The genconfig.py script can also use nodetool status to generate the server file using the -NS flag.

nodetool status | ./genconfig.py -NS

2. Connect to Scylla Manager by creating prometheus/scylla_manager_servers.yml If you are using Scylla Manager, you should set its IP and port in this file.

You must add a scylla_manager_servers.yml file even if you are not using the manager. You can look at: prometheus/scylla_manager_servers.example.yml for an example.

For example if Scylla Manager host IP is 172.17.0.7 prometheus/scylla_manager_servers.yml would look like:

# List Scylla Manager end points

- targets:
  - 172.17.0.7:5090

Note that you do not need to add labels to the Scylla Manager targets.

Configure Scylla nodes using Scylla-Manager Consul API¶

Scylla Manager 2.0 has a Consul like API.

When using the manager as the configuration source, there is no need to set any of the files. Instead you should set the scylla-manager IP from the command line using the -L flag.

For example:

./start-all.sh -L 10.10.0.1

Connecting Scylla-Monitoring to ScyllaDB¶

Scylla-Monitoring version 3.5 and higher can read tables from a ScyllaDB node using CQL. If your ScyllaDB cluster is user/password protected (See Scylla Authorization) you should assign a user and password for the Scylla-Grafana connection.

You can limit the user to read only, currently it only read table from the system keyspace.

You can set a user and password from a file or environment variables.

If the environment variables SCYLLA_USER and SCYLLA_PSSWD are set, they will be used.

To set the user and password from a file, edit grafana/datasource.scylla.yml. Uncomment the secureJsonData part and set the user and password.

Use an external directory for the Prometheus data directory¶

The -d flag, places the Prometheus data directory outside of its container and by doing that makes it persistent.

If the directory provided does not exist, the start-all.sh script will create it. Note that you should avoid running docker as root, the start-all.sh script will use the user permissions that runs it. This is important if you want to place the prometheus directory not under the user path but somewhere else, for example /prometheus-data.

In that case, you need to create the directory before calling start-all.sh and make sure it has the right permissions for the user running the command.

Add Additional Prometheus Targets¶

There are situations where you would like to monitor additional targets using the Prometheus server of the monitoring stack. For example, an agent that runs on a firewall server. The Prometheus server reads its targets from a file, this file is generated from a template when calling start-all.sh. To add your targets you would need to edit the template file before calling start-all.sh.

The template file is either prometheus/prometheus.yml.template if Prometheus reads the Scylla target from file, or prometheus/prometheus.consul.yml.template if Prometheus gets Scylla targets from the manager Consul API.

You can add a target at the end of the file, for example, the following example would read from a server with IP address 17.0.0.1 with a Prometheus port of 7000.

- job_name: 'myservice'
  # Override the global default and scrape targets from this job every 5 seconds.
  scrape_interval: 5s
  static_configs:
    - targets:
      - 17.0.0.1:7000

Start¶

./start-all.sh -d prometheus_data

Stop¶

./kill-all.sh

Start a Specific Scylla Monitoring Stack Version¶

By default, start-all.sh will start with dashboards for the latest Scylla Open source version and the latest Scylla Manager version.

You can specify specific scylla version with the -v flag and Scylla Manager version with -M flag.

Multiple versions are supported. For example:

./start-all.sh -v 2020.1,2019.1 -M 2.1 -d prometheus-data

will load the dashboards for Scylla Enterprise versions 2020.1 and 2019.1 and the dashboard for Scylla Manager 2.1

Accessing the localhost¶

The Prometheus server runs inside a Docker container if it needs to reach a target on the local- host: either Scylla or Scylla-Manager, it needs to use the host network and not the Docker network. To do that run ./start-all.sh with the -l flag. For example:

./start-all.sh -l -d prometheus-data

Configure rsyslog on each Scylla node¶

generates metrics and alerts from logs. To get full functionality, you should use rsyslog. Scylla Monitoring Stack will act as an additional rsyslog server. Scylla Monitoring Stack collects Scylla logs using Loki and generates metrics and alerts based on these logs. To use this feature, you need to direct logs from each Scylla node to Loki. The recommended method to do this is by using rsyslog, where Scylla Monitoring Stack (Loki) acts as an additional rsyslog server. .. note:: Scylla can send logs to more than one log collection service.

Prerequisite, make sure rsyslog is installed and running. If rsyslog is not installed, follow the installation instruction.

Add scylla’s rsyslog configuration file. Add the file: /etc/rsyslog.d/scylla.conf.

If Scylla Monitoring Stack IP is 10.0.0.1, the file should look like

if $programname ==  'scylla' then @@10.0.0.1:1514;RSYSLOG_SyslogProtocol23Format

Restart rsyslog for the configuration to take effect.

systemctl restart rsyslog