As part of development guides, it’s always a good idea to have a fallback plan and handle errors.
You can be 99.999% confident that your code won’t fail, but that 0.001% chance happens. “Anything that can go wrong will go wrong” – Murphy’s Law
And so, we resort to our very dear friend, Try-Catch.
In Logic Apps, it’s not exactly an out-of-the-box functionality, but it’s actually quite simple to achieve this and with a few steps. Also, there are multiple ways to catch your errors.
In this post, we will try two approaches:
Using a For-Each loop
and a Filter Array action.
Since I’ve started developing LAs, I’ve used the For-each loop approach but it had some flaws. It involved using a Parse Json to catch only the error message, but not all actions have the same schema.
So, the idea of the Filter array came to play. It’s actually quite easy as well and easy to maintain. You’ll find the same issue with the schemas, but it’s a faster approach.
Let’s dig in. I started to build a simple Logic App, just creating a couple of variables and an HTTP call that I know that will fail. I mocked the results to ensure the outcome is what I needed.
I’ve also built a scope, creating the Try block and a second scope to handle the Catch block. You’ll have to set the “Run after” properties to only trigger on errors, skips or timeouts, if not, it will run on success.
It will always relate to the previous scope.
The For-Each loop approach
Now we start to build our Error handler. I’ve chosen the For Each loop first because it was faster to create since I’m used to it and even have some templates for it as well.
The For Each action requires an array action to iterate on, which means we need to find one. The Scope isn’t a loop, so what will we relate it to?
Well, the scope might not be, but there are N actions inside it, so if you search in the expressions box or the documentation, you’ll find the “result” expression, which records every result of the contained actions within a given scope.
Now, remember, this will need to point to the action you want, but you will not have it in the Dynamic Content, you need to write it using the _ for spaces, because this expression handles the JSON node name like if you’re working in the back code.
Once you have this set, you just need to create a condition to check if the status of the action was “Failed“. Pretty simple.
If you test the execution, you’ll see that the loop is working and iterating the actions batch that the “result” expression returns.
I’m just returning the action outputs in the error string, which will contain the StatusCode, Headers and Body. It should help to diagnose a possible error.
Let’s try the Filter array now.
The Filter Array action approach
Similar to the For Each, we need to iterate through an action that contains child actions. We use the same “result” expression pointing to the same scope as the “From” property and choose “item()?[‘status’]” as the node to search for. Also, we only want the failed actions, so the node should be equal to “Failed“.
As for the error message, it’s a bit different from the For Each type. We’re still picking up the Outputs but we need to get the first action from the Filter array action.
The end result should be the same, as we’re picking up the same info as with the For Each loop.
Usually, an action will return a JSON record as the result of its execution. There are some fields that will always be present, like “Status” and “Tracking ID”. There’s no easy way to find this info, so you have to deconstruct one or more actions to find it. With the information you have now, you can get it from anywhere, you just have to use the “Result” expression.
Here you can see some fields in the Set var action I created and how the status is recorded. For tracking purposes, the execution engine records the begining and end timestamps as well as other useful data.
Now that you know how, it’s time to get working and make your Logic Apps sturdier and with a proper error handling.
Everyday we learn new things and when it comes to Logic Apps, we tend to learn even more, because it’s always shifting and new components are added. If we’re using ARM templates, the deployment brings out some challenges and with it, new things to learn (and lots of cute little things that make you want to bang your head against a brick wall).
Usually when we work with a CSV file we tend to keep the sorting according to the specification. It isn’t always alphabetical nor descending/ascending.
Sometimes, it’s just a real mess but it makes sense to the client and to the application that is consuming it.
A few days ago, whilst working on a client project and after dozens of tests, we started to see errors in our CSV file, where the headers and columns were arranged in a alphabetical sorting. This was not my intent, when I built the CSV array I wanted it to be in a certain order.
So why was this array now being sorted, who gave that command and how could I correct it?
Why and who:
As we dig in the Logic App code, we see that the Logic App is JSON in its core (my god, shocking development!). As such, it will follow JSON rules on sorting. If we set / append our variable with an array, even though that array won’t show up ordered in our code, it will when we deploy it to our Resource Group.
Lets prove this.
First, we set our LA in Visual Studio and initialize a string. Then we set two values to it ( “Append to string variable”) . One as a string and the other as an array.
Let’s look at the back code.
Looking good so far. Our strings are set and it’s in the order we want.
Lets deploy it to our RG and check again.
Well, there it is. In ARM deployment, if we write a JSON object, on deployment it gets sorted and will appear like this in the designer tool in Portal.
Funny thing is that if we change our object to the string we want, the designer will not recognize this as a change and doesn’t let you save.
Even in Code View the changes are not recognized.
But if we add other text to it, the changes are now recognized and Portal allows to save.
But still, it won’t show you the changes and will still sort out your CSV array, once again because it’s JSON.
A few weeks ago, this behavior wasn’t noticeable I had a few Logic Apps in place with the string array in a specific order and when deploying it didn’t get sorted.
I searched in Azure updates to see if anything was mentioned but nothing came up.
How to bypass this issue?
If you’re working with a CSV file like I was, after you build your array, you’ll need to build a CSV table.
The action “Create CSV table” will take care of this from you, but as we know, it will not be in the same format we need.
(notice I’ve switched to array variable because I can’t parse the string in JSON)
So, leaving the Columns in automatic mode will mess up your integration as you can see. The output will be sorted and it won’t be what you want / need.
What a mess!! This is nothing like we wanted.
We will need to manually define the columns headers and the value they’re going to have.
If you don’t have many fields, it’s quick to do this, but when you have lots of fields… well, let’s just say I hope you have plenty of time and don’t lose focus.
And there we have it. Fields are now displayed correctly, the data is in the right place and we’ve managed to get around this annoying problem.
Before we start with the actual post, I’d like to introduce a new brand we will be developing. This is the first official post with the “It’s not Rocket Science!” brand.
With this concept, we intend to explain how some procedures are not as complicated as you may think and that they’re not Rocket science. I’m open to suggestions on posts to demystify Azure Logic Apps and other Azure services.
So, welcome to a new concept and I hope you find it useful.
Azure Functions: Moving from Azure Portal to VS
Creating Functions in Portal presents some challenges, like lack of Intellisense, which, as we know, helps a lot. Not having CI/CD is also a concern and of the worse case scenarios:
Someone deleting you function by mistake!
Panic!, all hell broke loose. I tried to apply the same method as I did with the Logic Apps accidental delete recovery, but the “Change history” tab isn’t available for Functions. You end up losing your code, your executions and maybe some sleep over this.
The obvious next step is to get your backup from your repository and re-create the function. IF you have it in a repo.
We can’t prevent someone deleting our resources, everyone makes mistakes. But you can prevent letting your code sit in Azure Portal without version control, CI/CD and repository control.
So, the best way to do this is to migrate it to a VS solution. In this post, I will use VS2019, but VSCode is also available as others IDEs. You can do this right from the start by choosing another development environment besides the Portal.
With an existing Function, you’ll need a few things before you can migrate it. Besides your VS with an active subscription, you will also need the Azure SDK feature. This can be installed using the Installer you’ve downloaded from MS or in VS itself, in the “Tools”-> “Get Tools and Features” menu.
After a fresh install of Windows, I didn’t installed the Azure SDK, so I had to download it and install. According to the setup, it should take about 6,5GB.
If you had to install the SDK, Updates are also important, keep that in mind.
Lets return to the code.
The good thing about VS is that you don’t need to reference the required DLLs, they will probably already be there.
So you need to create a new Solution, with an Azure Function project.
Small note: you can also create a project using VB instead of C#, but… VB…
You can either choose a template with a trigger already created or you can choose an empty project, but when you try to Add a function, it will ask you again what template you want to use.
You can also add an empty class, but you will be missing some references.
As you can see, there are quite a few differences between the Class and the Function template.
I recommend you use the same template as the one you used to build your function, you will get more references that will be necessary for your code to work.
And now comes the easiest part. You can just copy-paste your code into VS, but leave the usings out. Most likely, if you haven’t used anything outstanding, they will already be there.
Now you have you code in VS, ready to run. Is it working properly? Well, you can just debug it locally, when pressing F5, the Azure emulator will start and you will be able to test your function like it was on the cloud.
You can just use your Postman or another web request tool to test your project.
Once you’ve tested everything and are ready to deploy to your subscription, you’ll need configure the publishing profile.
You have two major ways of doing this. You can choose the blue pill and configure your connection by hand or you take the red pill and download the profile from the existing FA.
My advice, get the publish profile. Saves you time and it’s Plug’n’Play.
And that’s it. Your newly migrated function is now ready for your CI/CD and you can manage and version it with VS and DevOps.
Now, this does have a catch, or not depending on how you look at it. Because we deploy using a Zip file, the code is no longer available in the Portal, you must now always use VS to view it.
I like this, because it means that from a Security perspective, noone will be accessing the source code through the Portal and it forces new Devs, and old ones too, to join the best practices policy and have everything in a proper Repo and version controlled.
Sometimes I have the need to have a Logic App (LA) disabled when I deploy it. For instance, when deploying to Production, I like to have my LAs disabled, because I want to double check everything before starting the process.
This is helpful because usually, when using the “Recurrence” trigger, the LA will start immediately. If for some reason, a connector has the wrong configuration or is broken or the end system is offline, the execution will fail. Other scenarios can happen as well, but that’s another story.
An interesting fact is that you don’t have a proper way to control this in the Portal. You can add the control line to the code, but you won’t be able to control it with CI CD.
So, in comes Rocket science (or not).
The resource code contains a property that will allow you to control the state of a LA and it’s quite easy to set. If you do not specify this property, the LA will start enabled and will trigger if it can.
The property is called “state” and lies within the “properties” node. Setting this property as a global parameter, allows you to prepare your CI/CD pipeline also allowing to parameterize this in your release.
This is quite and easy and simple insert, that should take no more than 5 minutes for you to configure.
If you choose the “Disabled” state, the LA will not start unless you specifically activate it.
Most developers start working with Logic Apps through Azure Portal, because it’s fast and direct. You just open the Portal, create your resource and start working. This is fine but it comes with a cost. There are several limitations to what you can do, specially when it comes to CI/CD (Continuous Integration/Continuous Delivery).
To handle this, there is the need to move to Visual Studio and start working from there. For this to happen, you need tools to help you and there’s a few available. In this post, I will approach a very good one and how to use it.
This tool is a collection of powershell scripts that will download to file your Logic App code and it also can create a parameters file.
I dropped into a Shared folder, because I’ve referenced it in a Repo for other people to consume in our projects, but this is not necessary, although I recommend it so that it becomes easier for future developers in your company.
After executing this, you’ll be ready to download your ARM template. So, get your Resource Group ID, you Subscription ID and prepare an output folder. You will also need to enter your credentials to login by powershell.
The script should be changed according to your IDs. Do note that it should not be case sensitive. If you don’t set the Out-File, the output will be set in the powershell console, you’ll still be able to copy it and paste in a file, but it’s an unnecessary step.
You will now have both files you need to manage your Logic App, so just copy them to your VS Azure Resource Group project, with Logic Apps Template and you’re almost ready to go.
You will need to address the path links in the JSON code to make them CI/CD-able and fix the parameters in some connectors, but there’s not a lot of work to be done.
As you can see, the ARM template already provides all connection parameters and connections variables. I do recommend you changed them to a more appropriate naming convention like “arm_O365”, “arm_SQL” or “arm_ServiceBus”. This way you will know what it’s referring to with a very understandable pattern.
At the end of the day, your Logic App should be ready for deployment in your subscriptions and look something like this:
Suggestions have been made in Azure Feedback, but so far, no replies.
So, how exactly do you recover a deleted Logic App?
Well, you have to dig a little bit and do some magic, but you will end up with a working Logic App after this.
First, you must navigate to the Activity Log of your Resource Group.
There, you will find the last operations executed. This may not be easy, in this example I only have a few operations, but in the client tenant, I had to scavenge through a few days of logs.
Once you find the correct deleted workflow AKA Logic App, you open it and check the Change History. This should in preview but it will be life boat.
The “deleted resource” contains the JSON code and it is what we’re looking for. Although it requires a bit of magic dust to clean the data that’s in it, it does contain the most recent code you had. Migrating this to a new Logic App, either in Portal using Code View or in a VS solution, this is the best way to recover your little mistake.
The end result, should look like this:
And your Logic App should be ready to run!
It may not be the best way to get this nor the fastest, but it works and there’s no proper documentation for this. Hopefully, Microsoft will release a more convenient way to get your deleted code.