Tutorials
Your health check says OK while your database is down
Fix a health check that misses database failures
Community
Things we had to work out, written down
Tutorials, explainers and fixes for the parts of running your own infrastructure that are only obvious afterwards. Each one was run on a machine we built for it, and the transcript is what the article is written from.
Tutorials
Step by step, on a machine we actually built. Every command in these was run before it was written down.
Tutorials
Latency, jitter and packet loss look different on your side
Tell latency from jitter from loss in your monitor
Tutorials
Two services on port 9000 split my traffic 8 to 12
Find and fix two services sharing one TCP port
Tutorials
Send push notifications from a shell script with ntfy
Set up ntfy and send alerts from any shell script
Tutorials
Ping works but port 443 refuses with no firewall
Find why TCP 443 is refused when ping works fine
Tutorials
Monitor an SSL certificate from outside your network
Check certificate expiry from a second machine
Tutorials
Alert before the disk fills, not after the database dies
At 23% used the disk had four hours left
Tutorials
Revoke an SSH key from ten servers without Ansible
grep -v exits 1 when it removes every line from a file
Tutorials
SSH drops when idle and ServerAliveInterval does not help
ClientAliveInterval 30 did not drop a single idle session
Tutorials
Prove your MongoDB backup by restoring it every night
mongodump exits 0 on a database that does not exist
Tutorials
Set up an SSH jump host so private servers stay private
ssh -i key -J bastion silently ignores -i on the jump
Tutorials
systemd says active and nothing is listening on the port
Three of four units said active with nothing listening
Tutorials
Build a dead-man switch so silent cron failures alert you
A removed crontab entry produces zero log lines
Tutorials
Fix Nginx 502 when the upstream is already listening
Four 502s and one 504, each a different log line
How it works
The mechanism underneath, for when knowing why something behaves that way is what stops it happening again.
Questions
- Who writes these?
- We do, from work on our own fleet. Every tutorial is run end to end on a disposable virtual machine first, and the article is written from that transcript rather than from memory. Where a piece states a number, it is one that was measured.
- Do I need a PingFleet account to use them?
- No. Nothing here needs an account and nothing is gated. Some articles end by pointing at how we monitor the thing they just set up, because that is the product, but the article stands on its own without it.
- Can I suggest a subject?
- Yes, at [email protected]. The most useful suggestions are the specific ones: the error message you searched for and could not find a straight answer to is worth more to us than a broad topic.