Adding a wait for sql strategy

[erdemtoraman]

#121

A simplified sql db waiting strategy without adding any new dependency to the library. An example usage for a postgres container:

	var env = map[string]string{
		"POSTGRES_PASSWORD": "password",
		"POSTGRES_USER":     "postgres",
		"POSTGRES_DB":       "service",
	}

	var port = "5432/tcp"

	dbURL := func(port nat.Port) string {
		return fmt.Sprintf("postgres://postgres:password@localhost:%s/service?sslmode=disable", port.Port())
	}

	req := testcontainers.GenericContainerRequest{
		ContainerRequest: testcontainers.ContainerRequest{
			Image:        "postgres:latest",
			ExposedPorts: []string{port},
			Cmd:          []string{"postgres", "-c", "fsync=off"},
			Env:          env,
			WaitingFor:   wait.ForSQL(nat.Port(port), "postgres", dbURL).Timeout(time.Second*5),
		},
		Started: true,
	}
	container, err := testcontainers.GenericContainer(context.Background(), req)

	if err != nil {
		log.Fatal("start ", err)
	}
	mappedPort, err := container.MappedPort(context.Background(), nat.Port(port))
	if err != nil {
		log.Fatal(err)
	}
	defer container.Terminate(context.Background())

	log.Println("postgres container ready and running at port: ",mappedPort)
	time.Sleep(time.Minute)
	time.Sleep(time.Minute)

[mdelapenya]

What do you think about renaming this to ForDB and waitForDB? At the end of the day, we are waiting for the database. Using SQL for it seems an implementation detail.

[erdemtoraman]

that's a good point but I assumed it'd be more consistent to point out "sql" because it can only handle sql based databases, if we just call it forDB the client of this function might not immediately understand it'd not work for say mongodb.

[mdelapenya]

I agree in the sense using SQL distinguish from any other storage type. My only concern was related to my mind directly connecting waitForSQL to wait for the execution of an SQL sentence... which on the other hand is true as we use SELECT 1.

So I'm good with this one :)

[ClaytonNorthey92]

could we add tests for this? maybe at least one for every SQL database type we support?

could we also add some documentation for this in the README?

[nikolayk812]

@gianarb what do you think about this PR?

[gianarb]

I would like to get it merged! @ClaytonNorthey92 @mdelapenya thumbs up and I will click the button!

[gianarb]

Thanks a lot @erdemtoraman !!
I created an issue to get an Example func for this feature #142

If anybody is up for it