Configure Airflow Slack URL using Terraform

[erikamov]

Description

This PR configures Airflow Slack URL using Terraform, so the variable is not removed anymore.

Resolves [#4363]

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation

How has this been tested?

Tested running "terraform plan" and "terraform apply" on staging.

Post-merge follow-ups

• No action required
• Actions required (specified below)

[github-actions]

Terraform plan in iac/cal-itp-data-infra-staging/composer/us

Plan: 0 to add, 1 to change, 0 to destroy.

Terraform used the selected providers to generate the following execution
plan. Resource actions are indicated with the following symbols:
!~  update in-place

Terraform will perform the following actions:

  # google_composer_environment.calitp-staging-composer will be updated in-place
!~  resource "google_composer_environment" "calitp-staging-composer" {
        id               = "projects/cal-itp-data-infra-staging/locations/us-west2/environments/calitp-staging-composer"
        name             = "calitp-staging-composer"
#        (5 unchanged attributes hidden)

!~      config {
#            (8 unchanged attributes hidden)

!~          software_config {
!~              env_variables            = {
+                   "CALITP_SLACK_URL_KEY"                                 = (sensitive value)
#                    (56 unchanged elements hidden)
                }
#                (6 unchanged attributes hidden)

#                (1 unchanged block hidden)
            }

#            (8 unchanged blocks hidden)
        }

#        (1 unchanged block hidden)
    }

Plan: 0 to add, 1 to change, 0 to destroy.

📝 Plan generated in Terraform Plan #603

[github-actions]

Terraform plan in iac/cal-itp-data-infra/composer/us

Plan: 0 to add, 1 to change, 0 to destroy.

Terraform used the selected providers to generate the following execution
plan. Resource actions are indicated with the following symbols:
!~  update in-place

Terraform will perform the following actions:

  # google_composer_environment.calitp-composer will be updated in-place
!~  resource "google_composer_environment" "calitp-composer" {
        id               = "projects/cal-itp-data-infra/locations/us-west2/environments/calitp-composer"
        name             = "calitp-composer"
#        (5 unchanged attributes hidden)

!~      config {
#            (8 unchanged attributes hidden)

!~          software_config {
!~              env_variables            = {
+                   "CALITP_SLACK_URL_KEY"                                 = (sensitive value)
#                    (56 unchanged elements hidden)
                }
#                (6 unchanged attributes hidden)

#                (1 unchanged block hidden)
            }

#            (8 unchanged blocks hidden)
        }

#        (1 unchanged block hidden)
    }

Plan: 0 to add, 1 to change, 0 to destroy.

📝 Plan generated in Terraform Plan #603

[vevetron]

Woops accidentally approved

[vevetron]

Terraform fail.

Erika can figure it out.

[erikamov]

I have another PR #4444 to give permission for Terraform to fix the error. :)
Our users already have this permission, so for me locally it worked.

[erikamov]

@vevetron Terraform permission Fixed!