I would like to be notified if anything important is wrong with the health of my HA instance. The notification should be hard to miss and should reach my phone no matter what (even if internet connectivity at home or on my phone is down).
One potential solution I am thinking of is:
Setup an automation in HA to send an “I am alive and well” message to some external Service.
If the “i am alive” message is not received within X minutes, the Service sends me an SMS notification. (Push notifications would not be reliable, since network may be down).
Do you know of any services that can help me with such a plan?
As long as you have some public url with content you want checked then https://uptimerobot.com works great. I use the free one to monitor my duckdns url and even they say it’s just checked every 5 minutes it normally see the error and notify much faster
I am tempted to say I would still prefer to employ “i am alive” messages from HA to the external monitoring service. Simply the URL being up is not a strong indication of health of the system.
I think it will be hard to find any service that will allow to basically let you DDOS them vs them controlling how often they check.
Be aware it is not just checking if site is up - uptime can also visit url and check if page has specific content. Meaning you can have your HA setup a public visible page that has text/content that you can tell uptime search for to decide if up or down.
I have a crazy suggestion. Find a friend with home assistant, set up a Telegram group chat (probably other ways of accomplishing this too) between you. Have each of your systems post status messages to the group chat. Your friends HA instance will check the status of your instance and vice versa.
vs them controlling how often they check.