App Service Swap - weirdness with Environment variables

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App Service Swap - weirdness with Environment variables

David Thielen 3,211

Hi all;

When I go to swap the dev slot with production, and I do the swap command in the dev slot, I'm getting some unexpected behavior in the environment variables. After the swap:

In the production slot it is as I expect
- dev slot - Deployment slot setting [x] - not moved/swapped to production
- production slot - Deployment slot setting [x] - not moved/swapped to production
- dev slot - Deployment slot setting [ ] - copied to production
- production slot, and no matching dev slot entry for this variable - Deployment slot setting [ ] - deleted. So a Deployment slot setting [ ] is a move (not copy) and the original production value is removed from production and there's no original dev value for that variable and so gone.
In the dev slot, not exactly what I expect
- dev slot - Deployment slot setting [x] - not moved/swapped to dev
- production slot - Deployment slot setting [x] - not moved/swapped to dev
- production & dev slot - Deployment slot setting [ ] - still the original value
- production slot, no matching dev slot entry for this variable - Deployment slot setting [ ] - not copied across
- dev slot, no matching production slot entry for this variable - Deployment slot setting [ ] - not deleted.

However the connection strings, which are all Deployment slot setting [ ], did swap each getting the other's values.

So why didn't it swat the Deployment slot setting [ ] from production to dev?

thanks - dave

Achraf Ben Alaya 1,301 Reputation points MVP

2024-02-24T09:00:42.31+00:00
It seems like you're encountering unexpected behavior when swapping deployment slots in Azure, particularly with regards to environment variables not being swapped as expected. Here are a few things to consider and potential reasons why this might be happening:

Slot Configuration: Ensure that both the source and target slots are correctly configured to swap the desired settings. Check if there are any specific configurations or flags that might affect environment variable swapping during the slot swap process.

Variable Scope: Verify the scope of the environment variables. Are they scoped to the slot or the app? If they are scoped to the app, they might not be affected by slot swaps. Ensure that the variables you're expecting to swap are scoped appropriately.

Slot Swap Limitations: Understand any limitations or restrictions related to slot swapping in Azure. There might be certain types of settings or configurations that are not supported for swapping or have specific behaviors during the swap process.

Slot Swap Process: Double-check the process you're following for performing the slot swap. Ensure that you're using the correct commands or procedures and that you're not inadvertently skipping any steps that might affect the swapping of environment variables.

Logging and Monitoring: Check the logs and monitoring data for any errors or warnings during the slot swap process. This might provide additional insights into why the environment variables are not being swapped as expected.

Azure Service Updates: Keep an eye on updates and changes to Azure services. Sometimes, unexpected behavior can be due to updates or changes in the platform that affect how certain features or functionalities work.

https://learn.microsoft.com/en-us/azure/app-service/deploy-staging-slots?tabs=portal#what-happens-during-a-swap?wt.mc_id=MVP_328341

If you've gone through these steps and are still experiencing issues, you may want to reach out to Azure support for further assistance. They can help investigate the specific configuration of your deployment slots and provide guidance on resolving the issue.

This answer was generated by chatgpt 3.5 and modified in order to add links from mslearn.
brtrach-MSFT 17,656 Reputation points Microsoft Employee

2024-02-24T23:08:42.02+00:00

@Achraf Ben Alaya As mentioned earlier this week, we welcome the usage of AI on Microsoft Q&A but you must highlight that the answer was generated by AI and the source of AI used. This answer is breaking the Q&A terms and conditions highlighted here. Thank you for helping to provide transparency and alignment of our policies on Q&A.

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brtrach-MSFT 17,656 Reputation points Microsoft Employee

2024-02-24T23:08:42.02+00:00

@Achraf Ben Alaya As mentioned earlier this week, we welcome the usage of AI on Microsoft Q&A but you must highlight that the answer was generated by AI and the source of AI used. This answer is breaking the Q&A terms and conditions highlighted here. Thank you for helping to provide transparency and alignment of our policies on Q&A.

Answer 1

brtrach-MSFT 17,656 Microsoft Employee

@David Thielen The connection strings since they were not stickied, moved as expected. They are a resource as highlight below that will swap.

Settings that are swapped:

General settings, such as framework version, 32/64-bit, web sockets
App settings (can be configured to stick to a slot)
Connection strings (can be configured to stick to a slot)
Handler mappings
Public certificates
WebJobs content
Hybrid connections *
Service endpoints *
Azure Content Delivery Network *
Path mappings

Features marked with an asterisk (*) are planned to be unswapped. Settings that aren't swapped:

Publishing endpoints
Custom domain names
Non-public certificates and TLS/SSL settings
Scale settings
WebJobs schedulers
IP restrictions
Always On
Diagnostic settings
Cross-origin resource sharing (CORS)
Virtual network integration
Managed identities and related settings
Settings that end with the suffix EXTENSION

Source

In regard to the other settings that are not stickied and did not swap, it's possible that the app settings are not being swapped because they are not present in both the source and target slots. When you swap deployment slots, only the settings that are present in both slots are swapped. If an app setting is present in one slot but not the other, it will not be swapped. Can you confirm this for us please? We look forward to your reply.

David Thielen 3,211 Reputation points

2024-02-25T00:59:13.2266667+00:00

@brtrach-MSFT I was not aware swap only happened if it was in both. I assumed a variable set only in one would move and end up set only in the target slot.
Mark A Evans 0 Reputation points

2025-05-01T21:56:24.15+00:00

@brtrach-MSFT are you sure about the comment you made that if a setting is not present on both slots, then it will not be swapped. How then would you roll out a new feature that needs a new variable? You can't add it to both and have zero down time.
Mark A Evans 0 Reputation points

2025-05-02T15:54:07.3933333+00:00

Man. I just read the docs. Slot settings are not what i though they were. Also they are no good if you want to use them for zero downtime new feature rollouts.

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