Terraform Datasources
- Data sources allow data to be fetched or computed in terraform configuration
- Navigate to the aws provider documentation and search for aws_subnet to find the datasources refer here
- Since we can write the query to fetch subnet ids, we can use for each expression of terraform
- The following expression which creates subnet associations can be changed to
resource "aws_route_table_association" "webassociations" {
count = 2
route_table_id = aws_route_table.publicrt.id
subnet_id = aws_subnet.subnets[count.index].id
depends_on = [
aws_route_table.publicrt
]
}
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For New approach Refer Here
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Now lets create an association for private subnets Refer Here
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Now destroy all and recreate
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This error has occured as terraform is trying to query the subnet ids before they are created
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So we need to create subnets first and then apply the whole template (This is not a good practice)
terraform apply -target="aws_subnet.subnets" .
terraform apply .
- depending on dynamic values by writing a data source will work in incremental mode of deployment, whenever you are trying to create the complete infra data sources if not used correctly might lead to these situations.
- So for this reason lets revert back to what we had for creating route table associations
- Refer Here for the changes reverted and the length function used.
