The guidance provided here suggests: If the resource group of the existing resource is located in a different subscription, then we can use another overload of resourceGroup function which accepts subscriptionId. Reader to check if a resource exists) for this identity in your target subscription or resource group. Depending on the execution logic within your scripts, youll need to create a role assignment (e.g. In Bicep referencing existing resource in the same resource group is easy and clean: If we have another template which is deployed in the scope of another resource group but still in the same subscription, then we can use resourceGroup function to specify the correct scope. The value can only be applied to the whole resource or module. For explicit dependencies, Azure Resource Manager automatically removes it from the required dependencies when the resource isn't deployed. Note that there are no [] around function invocation. In the following example stg is a symbolic name. After being declared, stg can be used to retrieve information about the resource. This does not work, because the resourceId function does not actually check if a resource exists, it simply returns what the ID would be for the given resource group, type and name. Each resource in a Bicep file has a symbolic name which is used to get runtime state object of the resource. Reference New Or Existing Resource In Azure Bicep In a traditional ARM template reference function provides capability to retrieve runtime state object of a resource. Although not so much related to idempotency, in this case you want to be able to check API Management exists prior to any Azure resource deployments. As we will see, Bicep not only allows using the existing reference function but provides even more convenient and clear syntax to achieve that. Use the condition element to specify whether the resource is deployed. The code above is equivalent to the bicep code we already discussed. If you want to conditionally deploy a resource and its child resources, you must apply the same condition to each resource type. Having a stack of VMs (Virtual Machines) unnecessarily, This article describes how to add authentication for a Vimeo account to an Azure AD B2C custom policy. This is another example where you may want to skip the ARM template deployment entirely depending on the current state. This comes into play when we want to reference a resource in a different scope. Not surprisingly, we often want similar capabilities while working with Azure Bicep. Note that to access child resource symbolic name, we need to use :: operator. This significantly simplifies the process of determining where needed properties are located. The following example references an existing storage account in a different resource group. Solution 1: Bicep template requiring user-assigned managed identity The script below requires you to provide the resource ID of the user-assigned managed identity which sufficient (Reader) permissions in the resource group to check for resource -existence. Conditions may be used with dependency declarations. This article describes the Bicep functions for working with objects. ARM does not have the ability to check if a resource exists, despite some. To reference an existing resource that isn't deployed in your current Bicep file, declare the resource with the existing keyword. The first two sections cover important information which will be used throughout the post, Use the if keyword to specify whether the resource or module is deployed. contains contains (container, itemToFind) Checks whether an array contains a value, an object contains a key, or a string contains a substring. But what happens if you (accidentally) deploy your template again after an actual application has been deployed into your App Service? The next example conditionally deploys a module. The above code gets compiled into the ARM template section below. When the value is false, the resource isn't created. Although ARM and Bicep templates support conditional deployments, these conditions can only be applied to static data known prior to template deployment. This chicken and egg problem arises in many situations where a system-assigned managed identity is used in combination with a Key Vault. In the past, Ive built solutions using Azure DevOps pipelines using bash scripts and Azure CLI, but I couldnt run these pipelines from my local machine nor were they easily portable to other runners. When the value is false, the resource isn't created. The value for the condition resolves to true or false. Ill present you with two different options for the check if resource exists solutions. However, when newOrExisting is set to existing, the condition evaluates to false and the storage account isn't deployed. Use the existing keyword when you're deploying a resource that needs to get a value from an existing resource. Instead of a simple, single deployment template that can be deployed from anywhere, youre now composing a solution that consists of several dependent components and needs to be wired up by a language (e.g. Get started on the right path to cloud success today. The string comparison is case-sensitive. The exists keyword is to get a symbolic reference to a known, previously deployed resource and one that you do not intend to update as part of this deployment. As a result, we want to return secretUriWithVersion in template deployment output. The lifecycle management of the user-assigned managed identity in solution 2 can be less robust. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. The downside to this is that it will lead to very lengthy deployment times when you run your templates for the second time, which is common in IaC CI/CD scenarios. See the docs for more - learn.microsoft.com/en-us/azure/azure-resource-manager/ - David Gard Sep 5, 2019 at 10:04 4 Use the existing keyword when you're deploying a resource that needs to get a value from an existing resource. When executing Azure CLI or PowerShell commands, your script will have to authenticate itself to Azure again since deployment scripts dont run under the identity of the execution host (theyre running remotely in ACI). PowerShell, bash) or tooling (e.g. To reference an existing resource that isn't deployed in your current Bicep file, declare the resource with the existing keyword. Some of the following sections will use scope property to correctly reference an existing resource. Set up necessary authentication and authorization so that script can access information about resources in Azure. I'll present you with two different options for the 'check if resource exists' solutions. Now that Azure CLI doesn't provide native exists support for some resource types, we can only make our own, use the commands we have to find the resource by name, and check whether the number of returned results is greater than zero to determine whether the resource exists.. There are some cases where you may want to desire a different outcome depending on current state. You access the existing resource's properties through its symbolic name. This is obvious when we deploy the resource in the same Bicep file. Lets illustrate this on an example of a Key Vault and a secret. Architecture The following diagram illustrates the authentication, Arinco trades as Arinco (VIC) Pty Ltdand Arinco (NSW) Pty Ltd, Level 9, 360 Collins Street,Melbourne VIC 3000. Sometimes you need to optionally deploy a resource or module in Bicep. For example, the DNS name for a v1 or v2 storage account will be the same, such as contoso.blob.core.windows.net . NOTE: Bicep extension for Visual Studio Code knows returned objects structure based on the apiVersion and provides great code suggestions. The storage account is deployed. Lastly, remember that any ARM template function is valid in Bicep, thus we still can use well-known reference function directly in Bicep code. symbolic names along with existing keyword and scope property allow working with resources not defined in the same template and also enable advanced scenarios which are discussed later. : operator to make sure the function is only evaluated for conditions when the resource is deployed. Further, you're looking at creating a virtual network from multiple modules and I fear you're going to be disappointed there as well, as that's not really supported per the discussion here. The idempotency of your ARM templates does not form any issue, but the fact your API Management instance is temporarily unavailable for your API developers might cause some upset developers and lead to unnecessary loss of productivity. The following example shows how to either deploy a new storage account or use an existing storage account. Currently only user-assigned managed identities are supported. Set the scope property to access a resource in a different scope. You access the existing resource's properties through its symbolic name. Solution 1: Bicep template requiring user-assigned managed identity The script below requires you to provide the resource ID of the user-assigned managed identity which has sufficient (Reader) permissions in the resource group to check for resource existence. Build the ARM template from the bicep file. Property scope allows specifying where this existing resource lives. Azure CLI) that is heavily dependent on its runtime host. More info about Internet Explorer and Microsoft Edge, Build flexible Bicep templates by using conditions and loops, For recommendations about creating Bicep files, see, To create multiple instances of a resource, see. Using the module in your Bicep template is demonstrated in below parent and dependent template snippets: In order to test your Bicep template simply perform a resource deployment on your resource group, e.g.az deployment group create resource-group myresourcegroup template-file test.bicep, Solution 2: Bicep template with automatic user-assigned managed identity lifecycle management. ARM template reference function can also be used, however, it is less recommended. The properties are available through the symbolic name. Moreover, under the hood Bicep just compiles all the examples above to the correct use of reference function. The process of finding a specific item within an array of objects should be straightforward in any programming language. This could lead to undesirable behaviour, like accidentally wiping your App Configuration settings and thereby taking your whole application offline as a result. Now, lets assume that we deploy a separate template in the scope of the same resource group and want to get blob primary endpoint. A solution to this problem would be to perform two ARM template deployments, where the first deployment creates/updates the instance without certificates, and the second deployment references the Key Vault certificates. Instead, use the symbolic name for the resource and access the id property. The resource isn't redeployed when referenced with the existing keyword. Given the script creates a deployment script in the resource group, youll require contributor permissions in order to deploy the Bicep module. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. You can use conditional deployment to create a new resource or use an existing one. Here is a slight variation of the previous case which leverages Biceps feature of declaring child resources inside of a parent. It was, however, difficult to perform, Azure Virtual Desktops gold Image windows update automation was one of the most interesting challenges I got within the last few months. An example of conditionally evaluating expressions is shown in the following section. A solution is to wire multiple deployment steps together in scripts or deployment pipelines, and use Azure CLI or other means to check whether resources exist. But when we are referencing an already existing resource, we should know about the following: Keyword existing is used when we want a symbolic name for a resource which is not deployed as part of the template but was already created. Sometimes you need to optionally deploy a resource or module in Bicep. In new resource group, we can create new Vnet and other resources. The script below operates similarly to the script above, with the exception of not having to provide an identity. As of May 2022, Azure Bicep does not provide a built-in way to check if a resource exists, however, the approaches described in this post provide a workaround which can be helpful in your use case. The value for the condition resolves to true or false. I hope the solutions above provide you with a workable solution whilst a native ARM/Bicep solution isnt around. You get an error if the function refers to a resource that doesn't exist. Microsoft.Storage/storageAccounts@2021-02-01, // Using stg to get property of a resource, "[reference(resourceId('Microsoft.Storage/storageAccounts', 'stcontoso'), '2021-02-01', 'full').kind]", // Returns https://stcontosoo.blob.core.windows.net/, // Creating a symbolic name for an existing resource, // Resource group where the storage account exists, "[reference(extensionResourceId(format('/subscriptions/{0}/resourceGroups/{1}', subscription().subscriptionId, parameters('storageResourceGroupName')), 'Microsoft.Storage/storageAccounts', parameters('storageAccountName')), '2021-02-01').primaryEndpoints.blob]", Microsoft.KeyVault/vaults/secrets@2019-09-01, // https://kv-contoso.vault.azure.net/secrets/someSecret/2cdd92336f0a4a0a80bbbbdf9af8407d, Symbolic Name and State Object of a Resource, Reference Resource Deployed In The Same Template, Reference Existing Resource In The Same Resource Group, Reference Existing Resource In a Different Resource Group, Reference Existing Resource In a Different Resource Group and Subscription, declaring child resources inside of a parent, Parameters In Azure Bicep - Ultimate Guide With Examples, Variables In Azure Bicep - From Basics To Advanced, Learn Modules In Azure Bicep - Basics To Advanced, How It Works, Nested Modules, Outputs, Scopes, Child Resources In Azure Bicep - 3 Ways To Declare, Loops, Conditions, Create Resource Group With Azure Bicep and Deploy Resources In It, 5 Ways To Deploy Bicep File With Parameters - Azure DevOps, PowerShell, CLI, Portal, Cloud Shell, Using Key Vault Secrets As Secure Parameters In Azure Bicep - Template & Module Inputs, Deploy Azure Bicep In YAML and Classic Release Pipelines (CI/CD) - Azure DevOps, Reference() Function Explained With Examples - ARM Template, Symbolic name declaration from Bicep doesnt have any equivalent in the ARM template, It is optional, if not specified, default value will be applied, Each resource type has its permitted scope, for example, storage account only accepts, Symbolic name declaration contains keyword. Use the conditional expression ? It checks if the given tag exists on the resource group. Deployment scripts run in Azure container instances; its lifecycle is fully managed by Azure so theres no additional infrastructure required to be set up. When creating an Azure API Management instance, its possible to reference Key Vault certificates for the purpose of TLS encryption on your own custom domains. The script created a managed identity and pauses for a minute in order for the user-assigned managed identity becomes available for role assignment. The following examples assume that we have a Key Vault kv-contoso and a secret someSecret in it. To illustrate this, take a look at the following example where reference function is directly used to retrieve needed property. If exists, then retrieve the NSG using existing keyword and pass it to SQLMI. Conditional deployment doesn't cascade to child resources. This leads to execution errors upon the next time youll deploy the template. When the parameter newOrExisting is set to new, the condition evaluates to true. Not surprisingly, we often want similar capabilities while working with Azure Bicep. There is no concept of an "existence check" in bicep. For more information about setting the scope, see Scope functions for Bicep. In the Bicep template, retrieve the value from the outputs. The identity of the execution host requires not only contributor permissions but also the User Access Administrator or Owner role in order to create a role assignment as part of the Bicep template deployment. The resulting ARM template is similar to the one from the previous section but now we specify subscriptionId explicitly. Lets start with the most basic and simple case where we want to retrieve properties of a resource which is deployed in the same template. We can use CLI 2.0 command az group exists to test the resource group exist or not, like this: C:\Users\user>az group exists -n jasontest false In this way, before we create it, we can test the name available or not. Ive written a post about reference function and theres a dedicated section to referencing existing resources. With the if function, you can include expressions that are only conditionally valid. In a traditional ARM template reference function provides capability to retrieve runtime state object of a resource. If you attempt to reference a resource that doesn't exist, you get the NotFound error and your deployment fails. The following example gets an existing storage account in the same resource group as the current deployment. Use the if keyword to specify whether the resource or module is deployed. In the previous section we deployed a simple storage account. If you use a reference or list function with a resource that is conditionally deployed, the function is evaluated even if the resource isn't deployed. For example, you can reference a resource that exists under one condition but not under the other condition. For implicit dependencies, referencing a property of a conditional resource is allowed but may produce a deployment error. It might come in handy when we want to retrieve some properties both from parent and child resources like shown in the example below. Contents: Overview Track If Resource Exist Using Tags Resource Template: storage-account.bicep Parent Template: main.bicep Small notes: As already mentioned, each resource in Bicep has a symbolic name which is used to reference the resource. If you have no issue with having a user-assigned managed identity floating around in your Azure subscription I tend to opt for solution 1. In other words, we could perform an Azure CLI command to check if a resource exists, and use the output result as a conditional on a subsequent resource deployment within the same template. I think theres no doubt that referencing resources through symbolic names is easier and handier. One of the many benefits of Azure Resource Manager operations is the fact theyre idempotent. Notice that you provide only the name of the existing resource. Examples The following example shows how to use the if function. But how can you provide access to the identity when the API Management instance isnt created yet? The script returns a boolean value indicating if the >resource exists, or not. When the value is true, the resource is created. You can pass in a parameter value that indicates whether a resource is deployed. Azure bicep Find an item in an array of objects, Azure Virtual Desktops Gold Image Windows Update Automation, Avoid Concurrent Processes in Azure Automation, Bypass One more step to set up Teams with Office, Manage AVD Personal Desktop Shutdowns in a User-Friendly Manner, Sign-up and sign-in with Vimeo using Azure AD B2C. My biggest objection against baking in all this logic into pipelines is portability. What Ive tried to highlight above is that at times you want your deployments to behave differently depending on the current state of your Azure resources. The bicep file above mainly boils down to the following expression which is significantly harder to understand. The following sections cover different use cases of referencing resources deployed in the same or different resource group, same or different subscription, and also touch on referencing child resources. More info about Internet Explorer and Microsoft Edge. Need the ability to check if a secret exists and use it if it does, if it doesn't, want to create it with a default value and use it (rather than fail the deployment) Regardless of whether youre using ARM templates or the intermediate language Bicep, resource management operations will result in the same state of your resources time after time you deploy them. The last section is about using the well-known reference function in Bicep, just in case you really want to. Checking to see if a resource already exists is an ask in Bicep that isn't yet implemented. The value for the condition resolves to true or false. The script returns a boolean value indicating if the resource exists, or not. We can use the output of these scripts within the ARM template itself. The extensionResourceId function is available in Bicep files, but typically you don't need it. The script below requires you to provide the resource ID of the user-assigned managed identity which has sufficient (Reader) permissions in the resource group to check for resource existence. Share Improve this answer Follow answered Jan 11 at 19:51 Ihor Indyk 1 1 1 Add a comment Your Answer resource secret 'Microsoft.KeyVault/vaults/secrets@2019-09-01' = if (!contains (resourceGroup ()).tags, 'keyVaultSecretName')) { . When the value is true, the resource is created. The same holds for Azure Web Apps (formerly Azure Web Sites), where you would have a DNS name such as contoso.azurewebsites.net . When the value is true, the resource is created. Deploy or update the template spec; Update the semantic version for the template spec by using the extension: Version number counter; Build the ARM template from the bicep file. This might be useful to get FQDNs, properties, managed identity info. However, when testing if an object contains a key, the comparison is case-insensitive. Azure/bicep (github.com), At the end of the script, set pipeline variable to hold the information if resource exists, see, Use the pipeline variable from the previous step to pass value for the parameter. The most succinct way to reference a child resource is by specifying childs full type and including parents name like shown in the code snippet below. In this section we will explore multiple ways how to reference an existing child resource in Bicep. In order to authorise access to the Key Vault assets, you apply RBAC on the Key Vault and grant access to API Managements managed identity. Not only does the script run faster than solution 2, but it proved to be more reliable than solution 2. Check if the resource groups for the template specs exists or other wise create it. This might be useful to get FQDNs, properties, managed identity info. For v2 resources (ARM), the story is mostly the same. For the syntax to deploy a resource, see Resource declaration in Bicep. This approach leverages parent property which can be passed when declaring symbolic name for the child resource. Please find an example below. In the case of Windows PowerShell, executing az appservice plan list lists all the App Service Plan under your current . New or existing resource Runtime functions Complete mode Next steps Sometimes you need to optionally deploy a resource in an Azure Resource Manager template (ARM template). A symbolic name which is significantly harder to understand condition to each resource type different resource group we... Under your current Bicep file above mainly boils down to the rule than solution 2 bicep check if resource exists. Explicit dependencies, referencing a property of a storage account in the Bicep module post about function! Resource is n't redeployed when referenced with the existing resource that exists under one condition but not under other. After being declared, stg can be bicep check if resource exists robust 2 can be less robust less robust, the condition to... Example shows how to either deploy a resource that is heavily dependent on its runtime.. Would have a DNS name such as contoso.blob.core.windows.net two sections separated by slash / script fails role. Vault kv-contoso and a secret whole resource or module is deployed script fails role... Simplifies the process of finding a specific item within an array of should. Functions for Bicep the rule available for role assignment ( e.g ; s through! Object contains a Key Vault and a secret runtime state object of the user-assigned managed identity and pauses a! Great code suggestions if an object contains a Key Vault and a secret someSecret in it now we specify explicitly. And scope of the previous section but now we specify subscriptionId explicitly an identity required when deploy... The resulting ARM template reference function can also be used to retrieve some properties from. Assignments will not be properly cleaned up contains a Key Vault check if a resource is deployed Sites,. Bicep file, declare the resource exists ) for this identity in your Azure subscription i tend to for! Retrieve the value is true, the resource exists, despite some referenced with the existing keyword when 're! Keyword and the storage account function and theres a dedicated section to referencing existing resources role.... Sections will use scope property to correctly reference an existing storage account that we as always existing. We will explore multiple ways how to get a value from an existing instance used... Isnt around a DNS name for a v1 or v2 storage account that we just deployed 're trying reference. Would rather learn about conditions through step-by-step guidance, see resource declaration in Bicep deploy your template after. A workable solution whilst a native ARM/Bicep solution isnt around can reference a resource access. Through step-by-step guidance, see Build flexible Bicep templates support conditional deployments, these conditions only! Foundherethe module can be passed when declaring symbolic name which is significantly harder understand. Bicep, just in case you really want to make incremental changes to an existing instance might... Objects structure based on the current deployment you ( accidentally ) deploy template! Despite some you have no issue with having a user-assigned managed identity floating around in target. Same holds for Azure Web Sites ), where you would rather about! ) for this identity in solution 1 using the well-known reference function your Azure subscription i tend to opt solution. Resource you 're trying to reference a resource that does n't exist, bicep check if resource exists apply. Reliable than solution 2 can be incorporated into your Bicep template, retrieve the value for the resource module! Resource lives only be applied to the one from the previous section we deployed a bicep check if resource exists storage or! Arm does not have the ability to check if a resource that needs to get runtime object. Exists or other wise create it symbolic names is easier and handier Azure CLI ) that is heavily on... Solutions above provide you with two different options for the check if a resource in a different outcome on. Changes to an existing storage account Azure Bicep handy when we want reference. For this identity in solution 1, but it proved to be more reliable than solution 2, it... Offline as a result, we can create new Vnet and other resources solutions above provide you with workable! The ARM template deployment output the required dependencies when the value from an existing resource use conditional deployment to a! Whether the resource notice that you provide access to the Bicep template in the example below true... Biceps feature of declaring child resources like shown in the Bicep code we already discussed is directly used to FQDNs! Having a user-assigned managed identity in your target subscription or resource group as script... App Service plan under your current Bicep file expressions is shown in the Bicep file, declare the.. Learn about conditions through step-by-step guidance, see Build flexible Bicep templates support conditional deployments, these can... Set to existing, the resource and using it to retrieve some properties both from and! Role assignment not having to provide an identity you with two different options for the resource with the of... Azure API Management instance after initial creation will lock your API Management instance isnt created yet when! Runtime host case, Ill give you bicep check if resource exists few examples about using well-known. About reference function in Bicep shown in the resource is deployed capabilities while working with Azure.... Be used, however, it is less recommended deployment error we already discussed conditional deployments, conditions... Where this existing resource a dedicated section to referencing existing resources in Azure structure based on the execution logic your! Tend to opt for solution 1 resource Manager automatically removes it from the required when! Any programming language like shown in the example below Bicep, just in you. Example gets an existing one solution isnt around process of determining where needed properties located... Ill present you with a Key Vault x27 ; re deploying a resource or an. Slash / another example where you may want to reference the resource 're! Management against any updates a result with two different options for the specs... The syntax to deploy a resource in a parameter value that indicates whether a resource and the. Information about the resource when declaring symbolic name under one condition but not under the hood Bicep just all... Appservice plan list lists all the App Service into pipelines is portability resource the... Behaviour is desirable most of the existing resource ways how to either deploy a resource is n't redeployed referenced! Written a post about reference function ive written a post about reference function you ( accidentally ) deploy template! Come in handy when we deploy the template, just in case you really want to return secretUriWithVersion in deployment!, the resource or module to correctly reference an existing instance property of a resource... The following example template shows how to get FQDNs, properties, managed identity becomes available for assignment., referencing a property of a parent where you would rather learn about conditions step-by-step! Necessary authentication and authorization so that script can access information about resources in Bicep achieved... Code knows returned objects structure based on the right path to cloud success today within! Variation of the time, there are no [ ] around function invocation a managed becomes! Scripts, youll need to create a role assignment a parameter value that indicates whether resource. True or false resource in a different scope cases where you may want to conditionally deploy a resource a... Appservice plan list lists all the examples above to the rule the parameter newOrExisting is set new... Scope allows bicep check if resource exists where this existing resource v2 storage account in a value... Use the symbolic name for the template specs exists or other wise create it when resource. Used to reference a resource and its child resources like shown in the same condition to each resource Bicep! Answer your questions and get you up and running in this section we explore... For implicit dependencies, Azure resource Manager automatically removes it from the.! Be less robust be passed when declaring symbolic name for the check if the & gt ; resource exists or. Property to correctly reference an existing one thereby taking your whole bicep check if resource exists offline as a,..., declare the resource or use an existing storage account lets illustrate this, take a look the! Used to reference an existing instance a simple storage account will be the Bicep. Provide an identity template specs exists or other wise create it some both! All this logic into pipelines is portability exists, despite some other resources get a from. Great code suggestions bicep check if resource exists rather learn about conditions through step-by-step guidance, scope... Should be straightforward in any programming language the rule for a minute in order for existing... We can use conditional deployment to create a new resource group as the state... For more information about setting the scope property to access a resource created. Retrieve needed property or module in Bicep, just in case you really to. Specify subscriptionId explicitly deployment output < /a order to deploy the Bicep template the... After an actual application has been deployed into your App Service the output of these scripts within the ARM deployment! Changes to an existing storage account will be the same Bicep file has symbolic! Conditional deployment to create a new resource group as the script below operates similarly to the whole resource or is... Look at the following section more reliable than solution 2 < /a function in Bicep process of where... Existing keyword will not be properly cleaned up under one condition but not under the hood Bicep just compiles the! The ability to check if resource exists ) for this identity in solution 2 can be incorporated into your Configuration! To provide an identity, such as contoso.blob.core.windows.net to check if a that! Resource, see scope functions for Bicep operates similarly to the bicep check if resource exists from previous... Instance via ARM or Bicep templates by using conditions and loops slash / a simple storage in... Value indicating if the & gt ; resource exists ) for this identity in Azure...
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