As per the docs the following should override the image defined health check. But it fails to override the image defined health check. This is important where the image defined health check is not applicable. One such example is using the creating a MySQL cluster in that the default health check is against mysqld which is not appropriate because either ndbd or ndb_mgmd is appropriate.

This leaves the container marked as unhealthy.

Using;

healthcheck:
  test: ["NONE"]

If you use the above to launch MySQL the default health check is used, inspect output following.

            "Healthcheck": {
                "Test": [
                    "CMD-SHELL",
                    "/healthcheck.sh"
                ]
            },

Resulting in;

21b30279e77d        mysql/mysql-cluster:8.0.18                          "/entrypoint.sh mysq…"   3 minutes ago       Up 2 minutes (healthy)     1186/tcp, 2202/tcp, 3306/tcp, 33060/tcp                                  dev-mysql
0fb50981bba5        mysql/mysql-cluster:8.0.18                          "/entrypoint.sh ndbd"    3 minutes ago       Up 3 minutes (unhealthy)   1186/tcp, 2202/tcp, 3306/tcp, 33060/tcp                                  dev-mysql-ndbd-2
8746135e3f8e        mysql/mysql-cluster:8.0.18                          "/entrypoint.sh ndbd"    3 minutes ago       Up 3 minutes (unhealthy)   1186/tcp, 2202/tcp, 3306/tcp, 33060/tcp                                  dev-mysql-ndbd-1
420fb8249df8        mysql/mysql-cluster:8.0.18                          "/entrypoint.sh ndb_…"   3 minutes ago       Up 3 minutes (healthy)     1186/tcp, 2202/tcp, 3306/tcp, 33060/tcp                                  dev-mysql-mgmd

The work around is to call a stub shell which simply calls exit 0.

    healthcheck:
      test: ["CMD-SHELL", "{{ mysql_config_directory }}/healthcheck.sh"]

Resulting in;

            "Healthcheck": {
                "Test": [
                    "CMD-SHELL",
                    "/etc/cell/dev/mysql/healthcheck.sh"
                ]
            },
 And;

aaf28f87abf0        mysql/mysql-cluster:8.0.18                          "/entrypoint.sh mysq…"   3 minutes ago       Up 3 minutes (healthy)   1186/tcp, 2202/tcp, 3306/tcp, 33060/tcp                                  dev-mysql
2df7948c37fc        mysql/mysql-cluster:8.0.18                          "/entrypoint.sh ndbd"    3 minutes ago       Up 3 minutes (healthy)   1186/tcp, 2202/tcp, 3306/tcp, 33060/tcp                                  dev-mysql-ndbd-2
1a3cd97cfc80        mysql/mysql-cluster:8.0.18                          "/entrypoint.sh ndbd"    3 minutes ago       Up 3 minutes (healthy)   1186/tcp, 2202/tcp, 3306/tcp, 33060/tcp                                  dev-mysql-ndbd-1
5fea532ef20f        mysql/mysql-cluster:8.0.18                          "/entrypoint.sh ndb_…"   3 minutes ago       Up 3 minutes (healthy)   1186/tcp, 2202/tcp, 3306/tcp, 33060/tcp                                  dev-mysql-mgmd

self.log('_get_expected_env')
        expected_env = dict()
        if image and image[self.parameters.client.image_inspect_source].get('Env'):
            for env_var in image[self.parameters.client.image_inspect_source]['Env']:
                parts = env_var.split('=', 1)
                expected_env[parts[0]] = parts[1]
        if self.parameters.env:
            expected_env.update(self.parameters.env)
        param_env = []
        for key, value in expected_env.items():
            param_env.append("%s=%s" % (key, value))
        return param_env
    def _get_expected_exposed(self, image):
        self.log('_get_expected_exposed')
        image_ports = []
        if image:
            image_exposed_ports = image[self.parameters.client.image_inspect_source].get('ExposedPorts') or {}
            image_ports = [self._normalize_port(p) for p in image_exposed_ports.keys()]
        param_ports = []
        if self.parameters.ports:
            param_ports = [str(p[0]) + '/' + p[1] for p in self.parameters.ports]
        result = list(set(image_ports + param_ports))
        self.log(result, pretty_print=True)
        return result
    def _get_expected_ulimits(self, config_ulimits):