Workflow API security
This section covers security related to the Workflow API.
This article covers the security aspects of using the Bubble Workflow API specifically. If you want to learn more about the Bubble Workflow API in general, you can check out the articles below:
Article: The Workflow API Article series: The Bubble API
The Workflow API allows external apps and systems to trigger specific workflows within your Bubble app. It provides a set of endpoints to initiate predefined sequences of actions or events in your app from outside sources. Naturally, opening up for external systems to activate workflows in your app can introduce potential vulnerabilities, so it's essential to learn how to use it correctly.
In this article, we'll explore how to set up API workflows that are secure.
Guiding principles in Workflow API security
The principle of least privilege
As discussed in various sections of our Security article series, the principle of least privilege remains important when working with the Workflow API. In this segment, we'll delve into methods and strategies to ensure adherence to this principle when setting up workflows that can be reached from outside of your own app.
In a bank, not every employee has the keys to the vault. A teller can access the cash drawer but doesn't have the authority to authorize large wire transfers. Conversely, the bank manager might have that authority but doesn't necessarily need access to every single safety deposit box.
Authentication and authorization
If you are reading this article series in order, you'll remember that we've talked extensively about authentication and authorization.
With the Data API, we explored how the what is basically the database; the data types, fields and operations that a specific user can access. The Workflow API is essentially the same, except that instead of protecting data, we're protecting workflows.
We'll still use the same mindset when planning our security: every client that wants to trigger workflows in your app need to go through the two steps of determining who they are, and what they have access to.
Authentication
When an API workflow is created, Bubble automatically generates a unique to trigger it, such as:
If the workflow required no authentication, knowing this URL would be enough for any actor (malicious or not) to trigger the workflow as many times as they want. Let's first talk about a few different reasons why you should be careful with that approach:
Running an API workflow spends server resource, just like other workflows in your app
If an API is repeatedly triggered, it can increase your consumption
If left completely unchecked and continuously running, the Bubble has safeguards in place to ensure your app doesn't spend too much server resources: this can lead to your app slowing down or even stopping completely
Running API workflows can potentially make a lot of changes in your database – by requiring authentication, you are adding one more potential safeguard on top of privacy rules and conditions in that workflow (we'll get back to this point later in the article)
While you are free to set up your API workflows as you see fit, we generally recommend that you always require authentication to run it.
Just like with the Data API, the access level of an API workflow can be split into three categories:
No clients have access to any API workflows (the Workflow API is disabled or all API workflows are unexposed)
Some clients have access to selected API workflows (the Workflow API is enabled, but requires authentication)
Everyone has access (the Workflow API is enabled, and no API workflows require authentication)
No one has access
The first scenario is that no client, whatever their credentials, have access to any API workflows at all. There are two ways to do this:
Disabling the Workflow API
The first way is to disable the Workflow API altogether under Settings - API.
This ensures that you don't have any Workflow API endpoints exposed at all, and nothing can be triggered from outside of your app. However, this also means that Bubble's backend editor will be disabled altogether, meaning that you cannot set up any internal API Workflows.
Disabling individual workflows
The second option is to keep the Workflow API enabled, but set every API Workflow that you create to be non-exposed. This means that the API workflow can be triggered internally in your app, but it will not have any endpoint that can be triggered from the outside.
Using this method gives you access to the backend editor and all of its features, but requires that you are careful with the settings on each individual API workflow.
Some clients have access to selected API workflows
The second option is to require authentication and open up for selected API Workflows to be triggered from outside of your own app.
Authentication
Authenticating clients to give them access to API workflows can be done in a few different ways. We go over this in detail in the article below:
Article: The Bubble API: Authentication methods
Exposing selected API workflows
Having set up the authentication, we can then proceed to set up which API workflows we want to expose.
API workflows are set to be exposed automatically when created – keep in mind that in this step you are disabling those you don't want to expose, and not the other way around.
To disable API workflows that you don't want exposed, uncheck the Expose as a public API workflow setting. This removes the endpoint of that workflow entirely, making it impossible to trigger regardless of authentication.
This way, only selected clients can run API workflows, and only selected workflows can be executed regardless of who the client is.
Everyone has access
The final option is to open up API workflows to be triggered by anyone, without having to authenticate at all. Generally, we don't recommend this, as this opens up for potential misuse.
To open up API workflows to be triggered without any authentication, check the two boxes as illustrated above. Optionally, you can check the last box (Ignore privacy rules when running the workflow) to give the broadest possible access to your data as well.
Authorization
With the Data API, authorization is generally linked to data – what a client can see and make changes to. With the Workflow API, the picture becomes slightly more complex: since we are dealing with workflows, there are two more ways you can fine-tune your authorization for each individual client:
(which can be protected with )
(which can set further restrictions on the workflow or individual action steps inside that workflow)
In the schematic illustration above, we can see the potential route a Workflow API request could take in terms of authorization.
First, Bubble determines who the client is (authentication), and then proceeds to check whether the client is allowed to run the workflow at all (Authorization 1). Then, the flow can potentially introduce two more authorization steps (illustrated as Authorization 2): a condition could stop the client from running the whole workflow or one or more of its actions, and privacy rules could limit the client's access to find data to make changes to.
Let's look at how this could look in the editor:
The API workflow may require authentication/authorization to run
The List of things to change may produce a limited result because privacy rules protect some or all records from being found in a search
The Only when conditional expression may prohibit the client from running the workflow, even if they are authenticated.
Data (privacy rules)
If you are unfamiliar with privacy rules, we highly recommend reading the articles below to get an understanding of how they work.
Article: Privacy rules Article: Workflow API privacy rules
After having set up the authentication method you want to use, you then need to authorize those clients to access data within the action steps in that workflow. This understanding is important to take in as you plan your security, or you may get unexpected results.
Let's look at an example to illustrate:
Adding some information to a list of users
Let's imagine that we have a Bubble app with 100 users. As we start exploring how to work with an external system through the Bubble API, we realize we need to add some data to all of those users. Essentially, we want to make a change to all of them.
We decide to set up an API Workflow to do that job, and we open up for external access so that this can be triggered from the external app.
Here's where the workflow versus data point becomes interesting. In this case, we are only authenticating once, but in principle we are going through two rounds of authorization:
Is the client allowed to run this workflow?
Is the client allowed to search for these users?
With this example, you can see why this could sometimes generate an unexpected result: while the client does have access to execute the workflow, they may not be able to actually search through all the users in the database.
Why is that? Because that data is protected by privacy rules, and the client does not match the needed credentials to download all of them. The unexpected result in this case might be that only a portion (or none) of the users were changed, as privacy rules stopped the client from finding them.
With the Data API, you can set specific privacy rules such as Modify via API, Create via API and so forth. Note that these settings apply to the Data API specifically; they do not affect an API workflow's ability to perform those operations.
Overriding privacy rules
If you want to give the broadest possible access level to your data, an API workflow can be set up to ignore privacy rules altogether. Again, we generally caution against using this method as it gives free access to all data in your database regardless of the privacy rules set.
Still, there are many scenarios where this is useful: just make sure you understand the implications of the setting.
Conditions
If you are unfamiliar with conditional expressions, we highly recommend reading the article below to get an understanding of how they work.
Article: Conditions Article: Dynamic expressions
In this second step of authorization you would likely be more deliberate about its implementation: conditions.
Conditions can be added to the workflow itself or to any of its action steps and the result would be the same. Bubble will check the condition against the client trying to execute the workflow, adding another layer of authorization.
Keep in mind that privacy rules can also influence conditions. For instance, if a condition depends on a database search to validate, it may not yield the expected results if the results are constrained by privacy rules.
In the example above, we've further restricted one of the actions in the API workflow by adding a condition that checks whether the current user (the authenticated client running the API workflow) as a field called Admin set to yes. If this returns a no, the step will not run.
Workflow API security checklist
Keep the principle of least access in mind (link)
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