Healthcheck

You can optionally add a healthcheck to any Lando service. This helps bridge the gap between when a service has started and when it is ready.

While this is not essential for every service it is useful in cases where you need to make sure things are in a good state before you proceed.

A good example is a post-start event that sanitizes a database. If you do not wait for the database to be ready then that post-start event may fail if it loses the "did I run before the database is ready race"?

Command

To add a healthcheck to a service you must specific a command which can be done a few ways:

services:
  database1:
    api: 3
    type: mariadb:10.4
    healthcheck: "mysql -uroot --silent --execute "SHOW DATABASES;"
  database2:
    api: 3
    type: mariadb:10.4
    healthcheck:
      command: mysql -uroot --silent --execute "SHOW DATABASES;"
  database3:
    api: 3
    type: mariadb:10.4
    healthcheck:
      - mysql
      - -uroot
      - --silent
      - --execute
      - SHOW DATABASES;
  disablebase:
    api: 3
    type: mariadb:10.4
    healthcheck: false

Note that these are equivalent commands. Also note that the array format can be used in either healthcheck or healthcheck.command.

Also note that you can disable the healthcheck with false.

User

By default all healthcheck commands are run as root however you can modify this using the object form of healthcheck as below.

services:
  database1:
    api: 3
    type: mariadb:10.4
    healthcheck:
      command: "mysql -uroot --silent --execute "SHOW DATABASES;"
      user: mysql

Retries

By default each healthcheck will be retried 25 times with a 1000 millisecond delay between retries but you can change this behavior as below.

services:
  database1:
    api: 3
    type: mariadb:10.4
    healthcheck:
      command: "mysql -uroot --silent --execute "SHOW DATABASES;"
      retries: 100
      delay: 10

Using the legacy healthcheck

You can also elect to use the legacy pre-3.20.0 healthcheck by editing the Lando global configuration.

config.yml

healthcheck: legacy

Alternatively you can use the legacy scanner by setting the environment variable LANDO_HEALTHCHECK to legacy. Here is a use-at-start example:

LANDO_HEALTHCHECK=legacy lando start

You can see whether the legacy scanner is being used with lando config and looking for the scanner key.

Note that the key will only be set if you elected to use the legacy scanner.

lando config --path healthcheck