[Android] SSH Client App JuiceSSH

Installed JuiceSSH on a Nexus5 for on-call SSH access, importing the private key via email.

How to Subscribe to Auth0 Status Page status.auth0.com RSS

Subscribe to status.auth0.com per your tenant domain via RSS in Slack to detect Auth0 incidents instantly.

[AWS] Moving from Private Subnet to Public Subnet to Reduce NAT Gateway Costs

How I reduced NAT Gateway costs by moving ECS Scheduled Tasks from a private subnet to a public subnet.

AWS Account Management Policy Comparison - AWS Organizations vs IAM Switch Role

Pros and cons of AWS Organizations vs IAM Switch Role for managing multiple AWS accounts.

[AWS] Sites to Check if Each Service is Running

A short memo of sites for checking whether AWS services are currently up and running.

[Cacti] Monitoring Target Addition Procedure Memo

A quick memo on adding a new monitoring host to Cacti and placing it in a Graph Tree.

Detecting Unknown Subdomains with Certificate Transparency — A Practical Introduction Using Cert Spotter

A practical guide to detecting new subdomains and SSL/TLS certificates issued under a root domain you own, from the outside. It walks through Certificate Transparency (CT) log fundamentals, subdomain discovery and continuous monitoring with the Cert Spotter API and crt.sh, the blind spots created by wildcard certificates and wildcard DNS, and a recommended layered setup that combines CT with Passive DNS.

IAM and Resource Management to Check First After Adopting Google Cloud Organization — Preventing Project Sprawl and Personal-Account Dependencies

The moment you finish provisioning a Google Cloud Organization linked to Google Workspace or Cloud Identity, the entire domain has Project Creator and Billing Account Creator by default. That default exists so the first admin cannot lock themselves out, and it is not a recommended steady state. If you leave it, you end up with 'My First Project' scattered directly under the Organization, external services still authenticating as former employees via OAuth, and billing no one can trace. This post walks through the IAM to inspect on day one, a safe procedure to narrow the roles without cutting yourself off, folder and naming conventions, cautions when moving existing projects into folders, angles for auditing external-service integrations, and a checklist you can hand to the next admin who joins the team.

Solution for large /tmp/magick-xxx files created by ImageMagick and policy.xml configuration changes

Cleaning up massive /tmp/magick-xxx files and tuning ImageMagick's policy.xml resource limits.

How to Write Incident Reports and Recurrence Prevention Plans

A personal memo on the minimum format for incident reports and recurrence prevention plans.

The Stance and Moves of Incident Response — Don't Blame, but the Owner Leads

If you operate systems, incidents are unavoidable. The question isn't whether you cause one, but how you move when it happens. I ask three things of my team. Don't blame the fact that it happened. But have the person closest to the cause take responsibility and lead the response. And let anyone in the room show leadership, regardless of title. Guided by blameless postmortems, Just Culture, and incident command, I work down to the concrete moves.

Solution for No space left on device error ~ inode depletion edition

Tracking down a No space left on device error on Linux to inode depletion caused by wp-file-cache.

Librato Metrics - Service for Metrics, Monitoring, and Alerts

A bookmark note on Librato Metrics, a SaaS for metrics, monitoring, and alerts.

[Linux] Command to Check Directories with High Disk Usage

Combine du and sort to find the top directories eating disk space on Linux when hit with a disk full warning.

[Linux] Command to Delete Old Files by Specifying Date and Time

Use find with -mtime / -atime and xargs rm to bulk delete old files on Linux when freeing up disk space.

[Linux/macOS] Batch Compress Files to .gz with gzip Command

Use gzip * to batch compress log files and free up disk space when hit with a sudden disk full incident.

[Linux] List of Directories That Should Be Backed Up

The minimum set of directories to back up on a Linux server: /home, /var, /usr, and /etc.

[Linux] who Command to Display Currently Logged-in Users

Use who --heading --users to inspect logged-in users, and cross-check stale ssh sessions with the w command.

Practical Introduction to Load Testing

A quick reading list for getting started with load testing — voluntas's intro gist and an AWS-focused book.

Configuration to include log files in subdirectories with logrotate

Add a nested glob pattern to your logrotate config so logs under subdirectories get rotated too.

Changed logrotate generation count to delete old log files

Reduce logrotate's rotate count and manually remove the leftover old logs to reclaim server disk space.

[Nagios] Changing Alert Email Content

Defining a custom Nagios notify command so alert emails are readable for non-engineer team members.

[Nagios] Changing check_load Settings for Load Average Monitoring

Tightening Nagios's check_load intervals so load average spikes get flagged sooner.

[Nagios] Configuration File Verification, Reloading, etc.

Nagios commands for validating configuration files and reloading them without a full restart.

Collection of Articles Useful for Nagios Introduction and Configuration

A curated reading list for getting started with Nagios and configuring it in practice.

[Nagios] Return code of 255 is out of bounds error occurs when NRPE is not running

Return code of 255 usually means NRPE isn't running on the monitored host — start it and enable auto-start.

How to configure Nagios to send notifications to Slack channel

Posting Nagios alerts to a Slack channel via Incoming WebHooks and a small shell script, avoiding the Integration limit.

[Nagios] Configuration Method for Operating from Web Management Interface

Fixing the Nagios web UI permission error by joining nginx to the nagios group and tuning cgi.cfg authentication.

net-snmp Installation and Configuration Method

Installing net-snmp with yum and configuring snmpd.conf, service startup, and iptables port rules for Nagios monitoring.

On-Premise vs Cloud Decision Criteria

Decision criteria between on-premise and cloud from a cost perspective, with Dropbox's AWS repatriation as a case study.

HTTP(s) Monitoring Service Pingdom

Setting up external HTTP(S) uptime monitoring for a personal site with Pingdom's free plan.

Reading Notes: 'Infrastructure Design Theory - From Requirements Definition to Operations and Maintenance'

Reading notes on 'Infrastructure Design Theory', covering non-functional requirements grades, availability, and ops design.

Presented Lightning Talk at 'Road to SRE NEXT@Fukuoka'

On May 9, 2025, I gave a lightning talk titled 'Getting Started with LLM Tracing for AI Apps Using Langfuse' at the SRE meetup 'Road to SRE NEXT@Fukuoka' held in Fukuoka. This article introduces the presentation content and slides.

Summary of Helpful Articles When Getting Started with SNMP

A link roundup of ITmedia and CodeZine articles I used to get started with SNMP.

Attended SRE NEXT 2024

Hybrid participation in SRE NEXT 2024. Attended on-site on day one and watched online on day two, gaining many insights.

Attended SRE NEXT 2025

I attended SRE NEXT 2025 on-site. This was my second consecutive year participating, following last year.

Free HTTPs monitoring service StatusCake

Migrating this site's HTTPs uptime monitoring from Pingdom to the free StatusCake plan, with Slack alerting.

Understanding Load Average

Notes on reference articles for understanding load average on multi-core Linux systems.