HEREDOC formatting of condition.statement always detects a change

[querry43]

Terraform Version

Terraform v0.11.11
+ provider.fastly (unversioned)

commit 693ea75e2b2d89079d5aa446d3b0c2163dafbc8f (HEAD -> master, origin/master, origin/HEAD)
Merge: b45327d 4c1c2b8
Author: Radek Simko <[email protected]>
Date:   Tue Jan 29 17:19:45 2019 +0000

    Merge pull request #121 from terraform-providers/t-fix-vcl-snippet-acc-test

    Fix VCL snippet acceptance test

Affected Resource(s)

Please list the resources as a list, for example:

• fastly_service_v1

Terraform Configuration Files

provider "fastly" {
}

resource "fastly_service_v1" "test_service" {
  name = "msh-test-service"

  condition {
    name = "multiline-line-condition"
    statement = <<EOF
req.url == '/foo'
EOF
    type = "REQUEST"
    priority = 10
  }

  domain {
    name    = "w.underdogma.net"
  }

  backend {
    address = "52.10.117.29"
    name    = "v1"
    port    = 80
  }

  force_destroy = true
}

Debug Output

https://gist.github.com/querry43/98e192d17f3c0404a6a66f12ac45eafe

Panic Output

Expected Behavior

When a condition statement is represented with a heredoc, but the contents of the heredoc do not change, terraform should determine that there is no change to apply.

Actual Behavior

Terraform always applies a diff.

Steps to Reproduce

Please list the steps required to reproduce the issue, for example:

1. terraform apply

Important Factoids

It looks like the set hash is changing and causing the resource to be recreated. At first I thought it was related to \n literals in the json, but if that was the case, then the following diff should have resolved it. It did not.

diff --git fastly/resource_fastly_service_v1.go fastly/resource_fastly_service_v1.go
index 8332b74..19e693a 100644
--- fastly/resource_fastly_service_v1.go
+++ fastly/resource_fastly_service_v1.go
@@ -84,7 +84,7 @@ func resourceServiceV1() *schema.Resource {
                                                        StateFunc: func(v interface{}) string {
                                                                value := v.(string)
                                                                // Trim newlines and spaces, to match Fastly API
-                                                               return strings.TrimSpace(value)
+                                                               return strings.TrimSpace(strings.Replace(value, "\n", " ", -1))
                                                        },
                                                },
                                                "priority": {
@@ -1483,7 +1483,7 @@ func resourceServiceV1Update(d *schema.ResourceData, meta interface{}) error {
                                        Type:    cf["type"].(string),
                                        // need to trim leading/tailing spaces, incase the config has HEREDOC
                                        // formatting and contains a trailing new line
-                                       Statement: strings.TrimSpace(cf["statement"].(string)),
+                                       Statement: strings.TrimSpace(strings.Replace(cf["statement"].(string), "\n", " ", -1)),
                                        Priority:  cf["priority"].(int),
                                }

References

[ziggythehamster]

It seems to do this with a log format HEREDOC as well.

[ziggythehamster]

This seems to be some discrepancy around how Terraform stores things into the state with trailing newlines (it seems to strip them). If you put your HEREDOC into a local var, and then have a different local var which is "${chomp(local.my_heredoc)}", it may resolve this. (I don't understand why this is happening, but I am just saying what I read in our Fastly support channel.)

[fivetanley]

For anybody coming to this today, I followed @ziggythehamster's suggestion above, but used trimspace instead to remove whitespace from both ends of the string (instead of just the end) and now my terraform plans are clean

[ziggythehamster]

In the case of origin_ssl_cert_trust_chain, the cert chain must end in \n-----END CERTIFICATE-----\n (that is, newline, space, space), or you will forever see a diff. This seems to have cropped up in upgrading to Terraform 0.12 and affects heredocs just as much as it affects variables. I don't know why. :)

[gdubicki]

For me, when working with the snippet's content I had to:

• sometimes use chomp, sometimes not,
• I was not able to use <<-, only << for the HEREDOC.

I hope this helps someone struggling like me!