Download Terraform For Mac

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In my previous post, Infrastructure as Code and vRealize Automation, I talked about the principles of Infrastructure as Code and how vRealize Automation can help you put some of those ideas into action. I also mentioned Terraform as a complimentary technology to vRealize Automation. There are several VMware providers for Terraform (including vSphere, NSX-T, vCloud Director, vRealize Automation 7) which allow customers to consume VMware products in a programatic way. The vRealize Automation Terraform Provider, as well as a wide range of 3rd party providers, and can augment the functionality provided by vRealize Automation with additional external components (as demonstrated recently on Grant Orchard’s blog).

  1. Install Terraform
  2. Download Terraform Windows
  3. Terraform Downloads
  4. Terraform Download File

Download Terraform for free. Safely and predictably create, change, and improve infrastructure. Terraform is an open source tool that allows you to use infrastructure as code to provision and manage any cloud, infrastructure or service. It codifies APIs into declarative configuration files, which can then be shared among team members, reviewed, applied, edited and versioned.

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Update 05/2020 – The vRealize Automation Terraform Provider has been updated to v0.2.0, check out the release notes for up to date information on what’s new!

Installing the vRealize Automation Terraform Provider

To start using the vRA Terraform provider you’ll need to have Terraform and Go installed on your local machine. For Mac users you can install both using homebrew, for Windows users I’d recommend chocolatey. Up-to-date installation instructions for the vRA terraform provider are available on the Github repository, the steps I’m using below are used for a Mac.

I’ve created a new folder to hold my Terraform configuration files:

  • main.tf – this is my main terraform file in which I am describing the desired state of my environment
  • terraform.tfvars – used for setting variable values
  • variables.tf – used for declaring variables

Generating an API token

In order for Terraform to authenticate with the vRealize Automation API we need an API token – this can either be an access token, a refresh token, or an API token which is issued for a specific purpose. API tokens can be limited to a specific organisation scope, functionality, can be revoked, and can be set to expire. Access and Refresh tokens are based on your login credentials and expire in 8 hours or 6 months respectively, but share the scope and permissions as your user account, and cannot be revoked without disabling the account. For vRealize Automation 8 (on-premises) you will need to use the instructions or scripts provided to retrieve a refresh token.

To create a new API Token, log into VMware Cloud Services Console and navigate to User Settings > My Account > API Tokens > Generate Token

The generated token is given a meaningful name, an expiry, and scoped to a specific organization and permissions. Once the token is generated be sure to save it, we’ll need it in the next steps.

Configuring the vRealize Automation Terraform Provider

The vRA provider requires two bits of information for the initial configuration: the refresh token, and the API URL

Edit the terraform.tfvars file created earlier to include these two variables. We also need to tell terraform what provider we’re using, so edit the main.tf file to include the provider definition as shown in the code below.

The provider vra definition references the two variables we’ve configured in the terraform.tfvars file through the “var” keyword. Now we can run terraform init to see if the provider configures successfully.

Terraform Init

So far, so good – the provider is initialised and is ready to start configuring vRealize Automation!

Configuring Infrastructure Components with the vRealize Automation Terraform Provider

The first thing I want to do is configure some of the needed infrastructure within Cloud Assembly in order to deploy a virtual machine – the following components need to be configured to support my workload:

  • Cloud Account
  • Cloud Zone
  • Flavors
  • Images
  • Project

An AWS Cloud Account requires two additional variables in our terraform.tfvars file – an access key, and a secret key. These are my AWS credentials (that you might use for the aws cli, for example). The variables need to be declared, and while you can declare them in the main.tf file it’s better practice to declare them in a separate variables.tf file to allow for code re-use.

Terraform downloads

This is where the declarative and self-documenting nature of Infrastructure as Code comes into play – we can see at first glance what this will create a new Cloud Account named “AWS Cloud Account”, using the variables declared in variables.tf. There are two regions configured, and the Cloud Zone should have a tag – “cloud:aws”.

Executing terraform plan will describe what will happen if we run the code:

Now that we have a good idea what the code will do, we can use terraform apply to execute the code – the image below shows that the Cloud Account has been created with the correct regions selected, and the “cloud:aws” tag assigned.

An AWS Cloud Account deployed and configured Terraform

The same method can be used to build up a full description of the infrastructure end state we want to see – including the Cloud Zone, Flavor Mapping, Image Mapping and Project – everything that we need to begin deploying workloads.

Re-running terraform apply results in the new infrastructure being configured:

Creating a Blueprint

All of this infrastructure is great, but it’s really about the workloads. The following code creates a Blueprint in the Project and using the Flavor and Images created earlier. The “content” property of the resource is the YAML code of the blueprint itself.

Once again running terraform apply will create the blueprint

Deploying a blueprint

Finally, let’s deploy the blueprint using the ID of the blueprint we just created, and specifying the inputs. If you have multiple versions of a blueprint, you can specify the desired one using the “blueprint_version” property, without it the deployment will be the “Current Version”.

The blueprint is deployed and configured with the inputs specified in the vra deployement resource.

Conclusion

Hopefully this brief introduction to the vRealize Automation Terraform Provider and the world of Infrastructure as Code has been useful, I’ve only scratched the surface of what you can create. You can find out more about the vRealize Automation provider complete with code examples on the GitHub pages.

Related Posts:

  • Announcing General Availability of vRealize Suite…Announcing General Availability of vRealize Suite 2019, vCloud Suite 2019, and vCloud Suite 2019 Platinum!Taka Uenishi posted October 17, 2019
  • Delivering Modern Infrastructure for Modern Apps…Delivering Modern Infrastructure for Modern Apps with vRealize Suite 2019 and vCloud Suite 2019Taka Uenishi posted March 10, 2020
  • vExpert Cloud Management April 2020 Blog DigestvExpert Cloud Management April 2020 Blog DigestMatt Bradford posted 4 days ago

Terraform v0.12 is a major releasefocused on configuration language improvements and thus includes somechanges that you'll need to consider when upgrading. The goal of this guide isto cover the most common upgrade concerns and issues.

For most users, upgrading configuration should be completely automatic. Somesimple configurations will require no changes at all, and most otherconfigurations can be prepared by runningthe automatic upgrade tool. Please read onfor more information and recommendations on the upgrade process.

If you are a developer maintaining a provider plugin, please seethe documentation on 0.12 compatibility for providersto learn more about the changes that are required.

» Upgrade to Terraform 0.11 first

We strongly recommend completing an upgrade to the latest Terraform v0.11release first. This will give you an opportunity to address any changesrequired for the previous major version upgrades separately, rather thanmaking multiple changes at once.

In particular, if you are upgrading from a Terraform version prior to v0.9,you must first upgrade to Terraform v0.9 andswitch to initializing with terraform init, because v0.12 no longer includesthe functionality for automatically migrating from the legacy remote statemechanism.

This guide focuses on changes from v0.11 to v0.12. Each previous major releasehas its own upgrade guide, so please consult the other guides (available in thenavigation) to upgrade step-by-step to v0.11 first.

Terraform v0.11.14 (and any subsequent v0.11 releases) also include someadditional functionality to help smooth the upgrade, which we will use laterin this guide.

Prior versions of Terraform are available fromthe releases server.

» Pre-upgrade Checklist

Terraform v0.11.14 introduced a temporary helper commandterraform 0.12checklist, which analyzes your configuration to detect anyrequired steps that will be easier to perform before upgrading.

To use it, first upgrade to Terraform v0.11.14.Then, perform the following steps:

  • terraform init to ensure your working directory is fully initialized andall required plugins are installed and selected.
  • terraform apply to ensure that your real infrastructure and Terraformstate are consistent with the current configuration. The instructionsproduced by the checklist command assume that configuration and state aresynchronized.
  • terraform 0.12checklist to see if there are any pre-upgrade steps in thechecklist.

If all is well, the final command will produce a message like this:

As the message suggests, the next step in that case is to read the remainderof this page to prepare for and carry out the upgrade.

However, the checklist command may instead produce a list of one or more tasksthat we recommend you perform before upgrading to Terraform 0.12, because theyare easier to perform with a fully-functional Terraform 0.11 than with aTerraform 0.12 that has encountered compatibility problems.

The tasks it may suggest you perform could include:

  • Upgrading any provider versions that are not compatible with Terraform v0.12.We recommend upgrading to the latest version of each provider before upgradingbecause that will avoid changing many things in one step.
  • Renaming any resources or provider aliases that have names that start withdigits, because that is no longer valid in Terraform 0.12.
  • Upgrading any external modules the configuration uses which themselves havethe above problems.

In each case, the tool will give some direction on how to perform the task itis suggesting.

The output from terraform 0.12checklist is in Markdown format so that it caneasily be pasted into a Markdown-compatible issue tracker, should you wantto track the necessary tasks or share the work with other team members.

After all of the tasks are complete, run terraform 0.12checklist one more timeto verify that everything is complete. If so, continue reading the followingsections to complete the upgrade!

» Addendum: Invalid module names

There is one additional pre-upgrade checklist item that the Terraform team didnot become aware of until after the release of Terraform v0.11.14, and thuscannot be detected automatically by the checklist tool: renaming modules whichhave names that start with digits.

Terraform 0.11 inadvertently tolerated leading-digit names for modules as aresult of a validation bug, but Terraform 0.12 has corrected that bug and willreject such module names. Unfortunately, module names are also recorded instate snapshots and so a state snapshot created for a configuration with aninvalid module name will itself be invalid as far as Terraform 0.12 isconcerned.

You can address this in a similar way to what the checklist tool suggests forinvalid resource names and provider aliases:

  • Rename the module in your configuration.
  • Use terraform state mv module.old module.newin Terraform 0.11.14 toupdate the state to use the new name instead of the old name.

As with all of the pre-upgrade checklist items, be sure to run terraform applyonce more before upgrading in order to ensure that the latest state snapshot issynchronized with the latest configuration.

» Upgrading to Terraform 0.12

Before switching to Terraform 0.12, we recommend using Terraform v0.11.14 (orany later v0.11 release) to perform one last terraform init andterraform apply to ensure that everything is initialized and synchronized.

Once terraform apply shows no changes pending, switch over to a Terraformv0.12 release and run terraform init again to upgrade the working directorymetadata to v0.12 format. (Once you've done this, you'll need to delete the.terraform directory if you wish to return to Terraform v0.11, but noreal infrastructure or persisted state will be upgraded yet.)

It is possible that your configuration may be using configuration constructsthat are not Terraform v0.12 compatible and thus require upgrade. In that case,terraform init will produce the following message:

As mentioned in the message, Terraform has partially initialized the directoryjust enough to perform the configuration upgrade process, which is describedin the following section.

We recommend running the configuration upgrade tool even if you do not seethe above message, because it may detect and fix constructs that aresyntactically correct but still need some changes to work as expected withTerraform v0.12.

» Upgrading Terraform configuration

Terraform v0.12 includes a new command terraform 0.12upgrade that willread the configuration files for a module written for Terraform 0.11 andupdate them in-place to use the cleaner Terraform 0.12 syntax and alsoadjust for use of features that have changed behavior in the 0.12 Terraformlanguage.

Simple configuration files are likely to be understood by Terraform 0.12 as-is,because the language is still broadly compatible, but we recommend that everyonerun the upgrade tool nonetheless. Even if your configuration is alreadycompatible, the tool will update your configuration to use the cleaner syntaxavailable in Terraform 0.12, which should improve readability.

To run the command, first make sure that your local working directory is syncedwith your version control system so that there are no changes outstanding. Thiswill make it easier to review the changes that the upgrade tool is proposing,using the diff feature of your version control system.

With a fully-initialized working directory (all necessary providers and childmodules installed), run terraform 0.12upgrade to begin the process. By defaultit will print some information about what it is about to do and prompt forconfirmation:

If you answer yes, the .tf and .tfvars files in your current workingdirectory will be rewritten in-place.

The upgrade tool may also print out warnings about constructs it wasn't able tomigrate fully automatically; in that case, it will also emit comments into therewritten source files containing the special marker TF-UPGRADE-TODO, asa prompt for a decision you'll need to make to complete the upgrade.

Once the upgrade tool has successfully completed and you've resolved anyTF-UPGRADE-TODO prompts, use your version control tool to review the proposedchanges and then run terraform plan to see the effect of those changes.

In most cases, terraform plan should report that no changes are required,because the updated configuration is equivalent to before.

The remaining sections below describe both some common changes that the upgradetool is able to make automatically, and some other upgrade situations thatthe configuration tool may not be able to fully resolve. If you encounterany errors during the upgrade or during the subsequent terraform plan, thesections below may give some additional context for how to proceed.

Once you're happy with the updated configuration, commit it to version controlin the usual way and apply it with Terraform 0.12.

» Remote state references

The terraform_remote_state data source has changed slightly for the v0.12release to make all of the remote state outputs available as a single mapvalue, rather than as top-level attributes as in previous releases.

In previous releases, a reference to a vpc_id output exported by the remotestate data source might have looked like this:

This value must now be accessed via the new outputs attribute:

The upgrade tool will rewrite remote state references automatically to includethe additional outputs attribute.

Where appropriate, you can also access the outputs attribute directly towork with the whole map as a single value:

Another consideration for terraform_remote_state is that this data source mustbe able to parse the latest state snapshot for a separate Terraformconfiguration that may have been updated by a newer version of Terraform.To provide flexibility when upgrading decomposed environments that useterraform_remote_state, Terraform v0.11.14 introduced support for readingoutputs from the Terraform v0.12 state format, so if you upgrade all of yourconfigurations to Terraform v0.11.14 first you can then perform v0.12 upgradesof individual configurations in any order, without breakingterraform_remote_state usage.

Note that the config block should now be in the form of an assignment with the = sign:

» Attributes vs. blocks

Terraform resource configurations consist of both arguments that setindividual properties of the main object being described, and nested blockswhich declare zero or more other objects that are modeled as being part oftheir parent. For example:

In the above resource, instance_type, ami, and tags are both directarguments of the aws_instance resource, while ebs_block_device describesa separate EBS block device object that is connected to the parent instance.

Due to the design of the configuration language decoder in Terraform v0.11 andearlier, it was in many cases possible to interchange the argument syntax(with =) and the block syntax (with just braces) when dealing with maparguments vs. nested blocks. However, this led to some subtle bugs andlimitations, so Terraform v0.12 now requires consistent usage of argumentsyntax for arguments and nested block syntax for nested blocks.

In return for this new strictness, Terraform v0.12 now allows map keys to beset dynamically from expressions, which is a long-requested feature. Themain difference between a map attribute and a nested block is that a mapattribute will usually have user-defined keys, like we see in the tagsexample above, while a nested block always has a fixed set of supportedarguments defined by the resource type schema, which Terraform will validate.

The configuration upgrade tool uses the provider's schema to recognize thenature of each construct and will select the right syntax automatically. Formost simple usage, this will just involve adding or removing the equals signas appropriate.

A more complicated scenario is where users found that they could exploit thisflexibility to -- with some caveats -- dynamically generate nested blocks eventhough this wasn't intentionally allowed:

Terraform v0.12 now includes a first-class feature for dynamically generatingnested blocks using expressions, using the special dynamic block type. Theabove can now be written like this, separating the static block device fromthe dynamic ones:

The configuration upgrade tool will detect use of the above workaround andrewrite it as a dynamic block, but it may make non-ideal decisions for how toflatten your expression down into static vs. dynamic blocks, so we recommendreviewing the generated dynamic blocks to see if any simplifications arepossible.

Terraform v0.12 now also requires that each argument be set only once withina particular block, whereas before Terraform would either take the lastdefinition or, in some cases, attempt to merge together multiple definitionsinto a list. The upgrade tool does not remove or attempt to consolidateany existing duplicate arguments, but other commands like terraform validatewill detect and report these after upgrading.

» Integer vs. Float Number Types

From Terraform v0.12, the Terraform language no longer distinguishes betweeninteger and float types, instead just having a single 'number' type that canrepresent high-precision floating point numbers. This new type can representany value that could be represented before, plus many new values due to theexpanded precision.

In most cases this change should not cause any significant behavior change, butplease note that in particular the behavior of the division operator is nowdifferent: it always performs floating point division, whereas before itwould sometimes perform integer division by attempting to infer intent fromthe argument types.

If you are relying on integer division behavior in your configuration, pleaseuse the floor function to obtain the previous result. A common place thiswould arise is in index operations, where the index is computed by division:

Using a fractional number to index a list will produce an error telling youthat this is not allowed, serving as a prompt to add floor:

Unfortunately the automatic upgrade tool cannot apply a fix for this casebecause it does not have enough information to know if floating point or integerdivision was intended by the configuration author, so this change must be mademanually where needed.

» Referring to List Variables

In early versions of Terraform, before list support became first-class, werequired using seemingly-redundant list brackets around a single expressionin order to hint to the language interpreter that a list interpretation wasdesired:

This strange requirement was subsequently lifted after the introduction offirst-class list support, but we retained compatibility with this older usagefor a transitional period by including some fixup logic that would detect whenlist brackets contain list expressions and automatically flatten to a singlelist.

As part of implementing the first-class expressions support for v0.12, we neededto finally remove that backward-compatibility mechanism to avoid ambiguityin the language, so an expression like the above will now produce a list oflists and thus produce a type checking error for any argument that was expectinga list of some other type.

The upgrade tool is able to recognize most simple usage of this pattern andrewrite automatically to just refer to the list directly:

However, an unintended side-effect of this compatibility mechanism was toalso flatten mixed lists of single-value and list expressions into a singlelist automatically. We didn't intend for this to be a part of the language, butin retrospect it was an obvious consequence of how the compatibility mechanismwas implemented. If you have expressions in your modules that produce a listof strings by using list brackets with a mixture of string and list-of-stringsub-expressions, you will need to rewrite this to explicitly usethe flatten functionto make the special treatment more obvious to the reader:

The configuration upgrade tool unfortunately cannot make this changeautomatically, because it doesn't have enough information to know for certainwhich interpretation was intended for a given list.

For complex examples that the upgrade tool is not able to adjust automatically,subsequent Terraform operations may produce an error message like the following:

This message is reporting that Terraform has understood this expression as alist of lists, and therefore element zero is a list rather than a string. Tofix the error, remove the redundant list brackets and possibly add aflatten function call as described above, for more complex cases.

» Reserved Variable Names

In preparation for new features planned for future releases, Terraform 0.12reserves some additional names that can no longer be used as input variablenames for modules. These reserved names are:

When any of these names is used as the label of a variable block, Terraformwill now generate the following error:

The upgrade tool cannot automatically adjust for these reserved names, becauseit does not know what new name would be more appropriate. To proceed, you mustunfortunately rename these input variables and make a new major release ofthe module in question, since renaming input variables is a breaking change.

» Type Constraints on Variables

In Terraform v0.11, variables were documented as accepting only strings, listsof strings, and maps of strings. However, in practice Terraform permittedlists of lists and lists of maps and other nested structures in some cases,even though it was then generally inconvenient to work with those valueselsewhere in the module due to limitations of the index syntax, elementfunction, and lookup function.

Terraform now allows various type constraintsto be specified, as part of the language's new type system and generalizedfunctions and operators. However, because lists and maps of non-string valueswere not officially supported in 0.11, existing configurations do not haveenough information for the upgrade tool to know what element type was intended.It will therefore assume that lists and maps are of strings as documented,which will be incorrect for configurations using more complex structures. Theresult will be one of the following error messages:

To fix this, change the type argument from list(string) or map(string)to a more appropriate type constraint.

If you're not sure what type constraint to use yet, another option is touse the type constraint any, which will effectively disable validation andallow any value. We recommend using specific types where possible, but selectingany during upgrade may be preferable, so that the work to select and definea more precise type can be saved for a later change at your leisure, onceupgrading is complete.

» Working with count on resources

The count feature allows declaration of multiple instances of a particularresource constructed from the same configuration. In Terraform v0.11, anyuse of count would generally lead to referring to the resource in questionusing the 'splat expression' syntax elsewhere in the configuration:

Because aws_instance.example itself was not directly referencable inTerraform v0.11, the expression system allowed some flexibility in how suchexpressions were resolved. For example, Terraform would treataws_instance.example.id as an alias for aws_instance.example.*.id[0].

Terraform v0.12 allows referring to an entire resource as an object value,but that required making a decision on what type of value is returned byaws_instance.example. The new rules are as follows:

  • For resources where count is not set, a reference likeaws_instance.example returns a single object, whose attributes can beaccessed in the usual way, like aws_instance.example.id.

  • For resources where countis set -- even if the expression evaluates to1 -- aws_instance.example returns a list of objects whose length isdecided by the count. In this case aws_instance.example.id is an error,and must instead be written as aws_instance.example[0].id to accessone of the objects before retrieving its id attribute value.

The splat syntax is still available and will still be useful in situationswhere a list result is needed, but we recommend updating expressions likeaws_instance.example.*.id[count.index] to instead beaws_instance.example[count.index].id, which should be easier to read andunderstand for those who are familiar with other languages.

Another consequence of the new handling of count is that you can use thelength function directly with references to resources that have count set:

This replaces the v0.11 special case of aws_instance.example.count, whichcan no longer be supported due to aws_instance.example being a list.

The upgrade tool will automatically detect references that are inconsistentwith the count setting on the target resource and rewrite them to use thenew syntax. The upgrade tool will not rewrite usage of splat syntax todirect index syntax, because the old splat syntax form is still compatible.

Another count-related change is that Terraform now requires count to beassigned a numeric value, and will not automatically convert a boolean valueto a number in the interests of clarity. If you wish to use a boolean valueto activate or deactivate a particular resource, use the conditional operatorto show clearly how the boolean value maps to a number value:

» First-class expressions

Terraform v0.11 and earlier allowed expressions only within interpolationsequences, like '${var.example}'. Because expressions are such an importantpart of Terraform -- they are the means by which we connect the attributes ofone resource to the configuration of another -- Terraform v0.12 now allowsyou to use expressions directly when defining most attributes.

The generalization of expression handling also has some other benefits. Forexample, it's now possible to directly construct lists and maps withinexpressions using the normal syntax, whereas in Terraform v0.11 we requiredusing the list and map functions:

The automatic upgrade tool will perform rewrites like these automatically,making expressions easier to read and understand.

» Default settings in connection blocks

Terraform v0.11 and earlier allowed providers to pre-populate certain argumentsin a connection block for use with remote provisioners. Several resourcetype implementations use this to pre-populate type as 'ssh' and hostas one of the IP addresses of the compute instance being created.

While that feature was convenient in some cases, we found that in practice itwas hard for users to predict how it would behave, since each provider had itsown rules for whether to prefer public vs. private IP addresses, which networkinterface to use, whether to use IPv4 or IPv6, etc.

It also violated our design principle of 'explicit is better than implicit': wethink it's important that someone who is unfamiliar with a particular Terraformconfiguration (or with Terraform itself) to be able to read the configurationand make a good guess as to what it will achieve, and the default connectionsettings feature left an important detail unstated: how do the provisionersaccess the host?

With this in mind, Terraform v0.12 no longer performs any automatic populationof connection blocks. Instead, if you are using any remote provisioners youshould explicitly set the connection type and the hostname to connect to:

The automatic upgrade tool will detect existing connection blocks that arelacking these settings within resource types that are known to have previouslyset defaults, and it will write out an expression that approximates whateverselection logic the provider was previously doing in its own implementation.

Unfortunately in some cases the provider did not export the result of thepossibly-rather-complex host selection expression as a single attribute, and sofor some resource types the generated host expression will be quitecomplicated. We recommend reviewing these and replacing them with a simplerexpression where possible, since you will often know better than Terraform doeswhich of the instance IP addresses are likely to be accessible from the hostwhere Terraform is running.

» Equality operations must be valid on value and type

In 0.11, '1' would compare truthfully against 1, however, in 0.12,values must be equal on both value and type in order to be true. That is, in 0.11you would see:

Install Terraform

and in 0.12:

This means special care should be taken if you have any conditionals comparing to say,count.index where you were previously expecting it to be a string, when it is now a number.

This is a scenario where you would need to update existing 0.11 code to work as you expect in 0.12:

Also take care that if you have a variable that is a number, but defined as a string,the upgrade tool will not change it to a number, so take care to inspect your code:

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» Upgrades for reusable modules

If you are making upgrades to a reusable module that is consumed by manydifferent configurations, you may need to take care with the timing of yourupgrade and of how you publish it.

We strongly recommend using module versioning, either via a Terraform registryor via version control arguments in your module source addresses, to pinexisting references to the old version of the module and then publish theupgraded version under a new version number. If you are using semanticversioning, such as in a Terraform registry, the updates made by the upgradetool should be considered a breaking change and published as a new majorversion.

The migration tool will automatically add a >= 0.12.0 Terraform versionconstraint to indicate that the module has been upgraded to use v0.12-onlyfeatures. By using version constraints, users can gradually update their callersto use the newly-upgraded version as they begin to use Terraform v0.12 withthose modules.

For simpler modules it may be possible to carefully adapt them to be both0.11 and 0.12 compatible at the same time, by following the upgrade notes inearlier sections and avoiding any v0.12-only features. However, for any moduleusing a undocumented workarounds for v0.11 limitations it is unlikely to bepossible to both update it for Terraform v0.12 and retain v0.11 compatibilityat the same time, because those undocumented workarounds have been replacedwith new features in Terraform v0.12.

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» Map variables no longer merge when overridden

In prior versions of Terraform, a variable of type 'map' had a specialbehavior where any value provided via mechanisms such as the -var commandline option would be keywise-merged with any default value associated withthe variable. This was useful in early versions of Terraform that lackedmechanisms for doing such merging explicitly, but since Terraform v0.10introduced the concept of local values we consider it preferable to performsuch merges manually so that they are explicit in configuration:

In order to improve the consistency of variable handling across types, themap variable merging behavior is removed in Terraform v0.12. Because thismechanism was driven by command line options rather than configuration, theautomatic upgrade tool cannot automatically handle it. If you are relying onthe merging feature, you must reorganize your configuration to use explicitmerging like in the above example, or else your default map value will beentirely overridden by any explicitly-set value.

» Upgrading remote Backend Configuration

Terraform Cloud and Terraform Enterprise users will needto run terraform init -reconfigure to upgrade to Terraform 0.12.

Terraform provides a message stating that terraform init is required; whilethere is no harm in running this command, the next error message will clarifythat terraform init -reconfigure is required.

» Upgrading Sentinel policies

The Terraform Sentinel imports have been updated to work with Terraform 0.12.Care has been taken to ensure that the API is as backwards compatible aspossible and most policies will continue to work without modification. However,there are some important changes and certain policies will need to modified.

More information on the changes can be found in our page on using Sentinel withTerraform 0.12.

Terraform Downloads

It's strongly advised that you test your Sentinel policies after upgrading toTerraform 0.12 to ensure they continue to work as expected. Mockgeneration has also been updated toproduce mock data for the Sentinel imports as they appear in Terraform 0.12.

Terraform Download File

For more information on testing a policy with 0.11 and 0.12 at the same time,see the section on testing a policy with 0.11 and 0.12simultaneously.