Replace application already exists

[hmlanigan]

Description

CreateApplication in the juju package must be resilient to different already exists and not found errors. The method can be called when a new application resource is created, or when a RequiresReplace is triggered for the resource. In the case of RequiresReplace, DestroyApplication is called first. However we do not wait for the application removal to be done. Therefore we can get conflict errors when Creating an application with the same charm and or application name. Add retry functionality to account for this.

Side notes:

• Fixed placement of ",", which was getting in the way of test runs.
• Updated the integration resource example with needed info found during test.
• The juju api isn't returning typed errors, add a method to convert errors to types for use here.

Fixes: #272

Type of change

• Bug fix (non-breaking change which fixes an issue)

QA steps

Run terraform init && terraform plan && terraform apply with the following plan. Once it's active, update the plan by swapping the application names of "two" and "three", then run terraform plan && terraform apply.

terraform {
  required_providers {
    juju = {
      version = ">= 0.9.0"
      source  = "juju/juju"
    }
  }
}

provider "juju" {
}

resource "juju_model" "testmodel" {
  name = "replace"
}

resource "juju_application" "two" {
  model = juju_model.testmodel.name
  name = "juju-qa-test"
  units = 3
  charm {
    name = "juju-qa-test"
  }
}

resource "juju_application" "one" {
  model = juju_model.testmodel.name
  name = "ntp"
  charm {
    name = "ntp"
  }
  units = 0
}

resource "juju_integration" "juju-info" {
  model = juju_model.testmodel.name
  application {
    name = juju_application.one.name
    endpoint = "juju-info"
  }
  application {
    name = juju_application.two.name
    endpoint = "juju-info"
  }
  lifecycle {
    replace_triggered_by = [
      juju_application.one.name,
      juju_application.one.model,
      juju_application.one.constraints,
      juju_application.one.placement,
      juju_application.one.charm.name,
      juju_application.two.name,
      juju_application.two.model,
      juju_application.two.constraints,
      juju_application.two.placement,
      juju_application.two.charm.name,
    ]
  }
}

resource "juju_application" "three" {
  model = juju_model.testmodel.name
  name = "replace"
  charm {
    name = "ubuntu"
  }
}

Additional notes

JUJU-4529

[cderici]

Code looks good, previous errors I was hitting was because of mis-QA.

[cderici]

LGTM 👍

[hmlanigan]

Rebased to resole conflicts