introduce start-period and start-interval parameters to HEALTHCHECK

[aSeriousDeveloper]

• start period allows for a grace period for the container to boot
• start-interval allows for more frequent checking during this grace period
• also slightly increased the standard interval once the container is healthy

Resolves #541

See my comment for reasoning behind the values I've chosen.

[jaydrogers]

Sorry for the hiccup here, but could you try creating a new PR?

I had to move things in GitHub it automatically closed this PR. I don't see where I can update the branch into https://github.com/serversideup/docker-php/tree/280-create-a-frankenphp-variation

It won't let me change it when I press edit.

[jaydrogers]

NVM, I got it. I accidentally deleted the source branch. That's why it closed. I will be reviewing this for 4.0 and will keep you posted 👍

Sorry for the confusion!

[jaydrogers]

I love this proposal! Thanks a ton for sharing this, I learned a lot.

I summarized the changes here. Your proposal is brilliant 💯

Option	Description	Old Value	New Value
start-period	start period provides initialization time for containers that need time to bootstrap. Probe failure during that period will not be counted towards the maximum number of retries. However, if a health check succeeds during the start period, the container is considered started and all consecutive failures will be counted towards the maximum number of retries.	-	60s
start-interval	start interval is the time between health checks during the start period.	-	3s
timeout	If a single run of the check takes longer than timeout seconds then the check is considered to have failed.	3s	3s
retries	It takes retries consecutive failures of the health check for the container to be considered unhealthy.	3	3
interval	The health check will first run interval seconds after the container is started, and then again interval seconds after each previous check completes.	5s	10s