Production outages: timeline, root cause, fix, lessons learned.
A canary that a human watches on a dashboard is only as good as that human's attention. This guide covers automated canary analysis: which metrics to gate on, how to size steps and durations, how to handle low traffic, and the traps that make canaries pass when they should fail.
Automated trading fails fast: a bug can place hundreds of orders before a human notices. This guide covers the monitoring and stopping mechanisms we run for every bot: heartbeats, position and loss limits, cancel-all on disconnect, a tested kill switch, and runbooks for the first five minutes.
After a configuration refactor, a bot meant for the testnet connected to the production exchange with test parameters: order sizes ten times larger than production limits. A risk check caught it after four orders. This postmortem covers how environment selection failed and the guardrails we added.
When a server is slow and the dashboard is vague, a dozen standard commands narrow the problem to CPU, memory, disk, network or a single process in about five minutes. This is the order we run them in and how we read each output.
A summary of Cloudflare's official postmortem for the November 18, 2025 outage: a database permission change doubled a generated feature file, which crossed a hard limit and crashed the proxy. Plus the lessons we are applying to our own config pipelines.
A practitioner's reading of AWS's official summary of the October 19-20, 2025 us-east-1 disruption: a race in DynamoDB's DNS automation left an empty record, and recovery cascaded through EC2, NLB and Lambda. What happened per the report, and what we changed.
Our MySQL primary hung and then aborted with the data volume at 100%. Binary logs had grown to 410 GB because a backfill tripled write volume while retention had been raised for a lagging replica. How we recovered, purged safely and stopped it recurring.
We moved our app to a new host and switched DNS on a Saturday. A day later almost half of requests still reached the old server. A 24-hour TTL, a nameserver change with a 48-hour delegation TTL and an old zone left online kept stale answers alive. This is the postmortem.
Most deploy outages come from the same handful of gaps: no readiness check, killed in-flight requests, a migration the old code cannot survive, or no fast way back. This is the checklist we run before every release, with the reasoning behind each item.
A routine database failover lasted 20 seconds, but our API stayed down for 41 minutes. Three layers each made up to three attempts with no delay, multiplying load on the database by 27. Here is the math, the fix and how we proved it.
A practical guide to blameless postmortems: how to build a timeline, measure impact, find contributing factors instead of a culprit, write action items that get done, and run the review meeting so people tell the truth.
A slow accounting API pushed our PayPal webhook handler past the nginx timeout. PayPal saw a 504 and retried, while the first request was still running, and 41 wallets were topped up twice. Postmortem plus the idempotent design we moved to.
Our customer portal went dark at 07:12 when its Let's Encrypt certificate expired. Certbot's timer had run twice a day for a month and failed every time, because a firewall change blocked port 80. Here is how we traced it, fixed it and made expiry impossible to miss.
On November 3, 2024, our 01:30 billing run fired at 01:30 CDT and again at 01:30 CST, charging 1,284 subscriptions twice. The in-house scheduler matched local wall-clock time. We moved schedules to UTC and added idempotency keys, a run ledger and a unique constraint.
A practitioner's summary of CrowdStrike's official root cause analysis for the July 19, 2024 Windows crashes: a 21-field template read with 20 inputs, an out-of-bounds read in a kernel driver, and fleets stuck in boot loops. What the RCA says, and what we changed in our own releases.