Category Archives: Monitoring

Hardware, services and network monitoring systems

Redis: “psync scheduled to be closed ASAP for overcoming of output buffer limits” and the client-output-buffer-limit
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26 February 2020

We have a Redis-cluster with Master-slave replication and Sentinel, see the Redis: replication, part 2 – Master-Slave replication, and Redis Sentinel, Redis: fork – Cannot allocate memory, Linux, virtual memory and vm.overcommit_memory, and Redis: main configuration parameters and performance tuning overview posts. The system worked great until we started using it much more actively. Redis… Read More »

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Kubernetes: running metrics-server in AWS EKS for a Kubernetes Pod AutoScaler
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15 February 2020

Assuming, we already have an AWS EKS cluster with worker nodes. In this post – we will connect to a newly created cluster, will create a test deployment with an HPA – Kubernetes Horizontal Pod AutoScaler and will try to get information about resources usage using kubectl top. Kubernetes cluster Create a test cluster using… Read More »

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Grafana: Loki – the LogQL’s Prometheus-like counters, aggregation functions and dnsmasq’s requests graphs
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17 November 2019

The last time I configured Loki for logs collecting and monitoring was in February 2019 – almost a year ago, see the Grafana Labs: Loki – logs collecting and monitoring system post, when Loki was in its Beta state. Now we faced with outgoing traffic issues in our Production environments and can’t find who guilty for… Read More »

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dnsmasq: AWS – “Temporary failure in name resolution”, logs, debug and dnsmasq cache size
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28 October 2019

We are using AWS VPC DNS and sometimes facing with errors like “php_network_getaddresses: getaddrinfo failed: Temporary failure in name resolution“. The only advice from AWS tech. support was to configure a local dnsmasq service to act as a local DNS cache, but I did this already year ago and this issue happens once in 1-2-3… Read More »

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Debian: logrotate won’t rotate logs with an “unknown group ‘syslog'” error
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9 October 2019

We have an AWS EC2 with Debian and logrotate. One day its root partition was exhausted and when I started investigating it – found, that we have a bunch of files like /var/log/syslog.N.gz. At the same time by default logrotate creates a config file to rotate syslog log files: [simterm] root@monitoring-dev:~# cat /etc/logrotate.d/syslog # Ansible… Read More »

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OpsGenie: Uptrends integration
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24 September 2019

Uptrends – just a simple pinging monitoring service already used for the RTFM blog (see the Prometheus: RTFM blog monitoring set up with Ansible – Grafana, Loki, and promtail post for more details). Now I’d like to add it as an additional alerting service for the project’s API-endpoints and configure its alerts to be sent… Read More »

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Prometheus: Alertmanager’s alerts receivers and routing based on severity level and tags
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26 March 2019

We have three working environments – Dev, Stage, Production. Also, there are a bunch of alerts with different severities – info, warning и critical. For example: … – name: SSLexpiry.rules rules: – alert: SSLCertExpiring30days expr: probe_ssl_earliest_cert_expiry{job=”blackbox”} – time() < 86400 * 30 for: 10m labels: severity: info annotations: summary: “SSL certificate warning” description: “SSL certificate… Read More »

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Prometheus: Alertmanager – send alerts to a “/dev/null”
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26 March 2019

In addition to the Prometheus: Alertmanager’s alerts receivers and routing based on severity level and tags post. Have an Alertmanager config with routes. The task is – send all alerts from a Dev-environment into a “/dev/null”. To do this – create an empty receiver: … receivers: – name: ‘blackhole’ – name: ‘default’ slack_configs: – send_resolved:… Read More »

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