How to deploy a nodejs REST API backend dependent on redis on Azure?

Question

How to deploy a nodejs REST API backend dependent on redis on Azure?

Binit Gupta 0

I'm attempting to deploy my Node.js REST API backend on Azure, which relies on Redis for caching (or session management). My current setup uses Docker Compose, and I have already uploaded the images for both my Node.js backend and Redis to my Azure Container Registry (ACR). In my Docker Compose file, I'm referencing these images directly from ACR.

However, after deployment, I’m encountering two main issues:

Redis Connectivity Issue: The Node.js backend is failing to connect to the Redis server. The logs suggest that when my backend container starts, it cannot resolve or reach the Redis container. I suspect this may be an issue with network configuration within the Docker Compose deployment or possibly related to how Azure handles inter-container communication. I’ve double-checked that the Redis container is running and that the image is correctly defined in ACR. The connection string (or environment variable) pointing to Redis uses either the service or container name as defined in the Compose file.

Application Error on Accessing Backend URL: When I try to access the public URL of my deployed backend, I receive a generic "Application Error". This indicates that the backend isn’t starting correctly, likely due to its inability to connect to Redis.

MarkRuiz-MSFT 0 Reputation points Microsoft Employee

2025-04-13T21:30:47.6433333+00:00
Hi Binit,

Sounds like you already have done this, but I would double check to make sure that your Docker Compose file defines a network that both the Node.js and Redis are part of. That way they can communicate via that defined network.

Can you test the connectivity from a shell inside the Node.js container and try to ping the Redis endpoint? Does that work?

docker exec -it <backend-container-id> sh ping redis

Make sure the correct connection string is being used by your .js app. For example: if you Redis is named "redis", the connection string should like something like redis://redis:6379 Documentation: https://learn.microsoft.com/en-us/azure/azure-cache-for-redis/cache-troubleshoot-connectivity https://learn.microsoft.com/en-us/azure/container-apps/connect-apps
Siva Nair 2,420 Reputation points Microsoft External Staff Moderator

2025-04-14T06:22:21.55+00:00
Hi Binit Gupta,

Ensure proper network configuration and connectivity between your backend and Redis containers

Ensure that your Azure Container App environment is correctly set up to allow inter-container communication. If your application is integrated with a virtual network, confirm that the network settings allow DNS resolution for the Redis container. You may need to check if the Redis container is accessible from the Node.js backend by using the correct service name defined in your Docker Compose file.

Verify that the connection string or environment variable pointing to the Redis service is correctly defined in your Node.js application. The connection string should match the service name used in your Docker Compose file.

Ingress Configuration: If your backend needs to be accessible externally, ensure that the ingress settings are correctly configured. Check that the target port matches the listening port of your Node.js application.

As you got generic "Application Error" Ensure your backend listens on port 80, or set the WEBSITES_PORT App Setting to your container’s internal port (e.g., 3000).Check logs in the Azure Portal under Log Stream or Container Logs for the crash stack trace. Review the logs of both the Node.js backend and the Redis container for any error messages that could provide more insight into the connectivity issue. This can help identify if there are any specific errors related to network access or service resolution.

If you're using Azure Cache for Redis, ensure that your application is configured to connect to the Azure Redis instance rather than a local Redis container. You may need to adjust your connection strings accordingly. azure-cache-for-redis/cache-troubleshoot-connectivity

If you have any further assistant, do let me know.
Binit Gupta 0 Reputation points

2025-04-14T11:30:31.44+00:00

@Siva Nair I don't really have much of a expertise in azure, and i have been looking and searching a lot on youtube and docs but didn't found much, can you help me in detail?

Right now i am thinking this way... I have deployed a Azure cache for redis and then i'll use that connection string in my deployed backend image, will this work?

Also, when i am trying to deploy a azure cache for redis, its not getting deployed and just shows deployment is in progress.
Siva Nair 2,420 Reputation points Microsoft External Staff Moderator

2025-04-15T05:04:07.5933333+00:00
Hi Binit Gupta,

Yes, deploying an Azure Cache for Redis instance and using its connection string in your backend application is a valid and recommended approach.

Retrieve the Redis Connection String-cli-azure-redis

Retrieve the access keys:
az redis list-keys --name <your-redis-name> --resource-group <your-resource-group>

Retrieve the hostname:
az redis show --name <your-redis-name> --resource-group <your-resource-group> --query hostName
Construct the connection string using the retrieved hostname and access key.

As you mentioned Redis deployment is stuck, Use Azure CLI for Deployment:

Sometimes, deploying via CLI can provide more detailed error messages.
az redis create --name <your-redis-name> --resource-group <your-resource-group> --location <location> --sku Basic --vm-size C0

In the Azure Portal, navigate to "Deployments" under your resource group to check for any error messages.cache-monitor-troubleshoot-faq

Ensure your Node.js application is configured to connect to Azure Cache for Redis using the retrieved connection string. Ensure that the host, port, and password match the details from your Azure Redis instance.

Setting Environment Variables in Azure App Service- Under the "Configuration" section, add the following application settings:

Name: REDIS_HOST | Value: <your-redis-hostname>

Name: REDIS_PORT | Value: 6380

Name: REDIS_PASSWORD | Value: <your-access-key>

In your Node.js application, access these variables using process.env

If you have any further assistant, do let me know.
Binit Gupta 0 Reputation points

2025-04-15T07:18:30.1133333+00:00

@Siva Nair i deployed the redis instance as Azure cache for redis and backend as web app.

Inside this i configured the redis string using the hostname and password and it worked in local, i also checked whether my backend docker image is connecting to redis properly or not and it worked on local.

After that i pushed my image to ACR and the deployed the web app. Now my backend is deployed and all the routes which aren't dependent on redis works fine but the routes which uses redis caching fails.

I checked the logs and its having this error:

2025-04-15T07:01:58.788265901Z: [ERROR] 🚨 Redis connection error: ReplyError: Client IP address is not in the allowlist.

2025-04-15T07:01:58.788298971Z: [ERROR] at parseError (/app/node_modules/redis-parser/lib/parser.js:179:12)

2025-04-15T07:01:58.788426467Z: [ERROR] at parseType (/app/node_modules/redis-parser/lib/parser.js:302:14) {

2025-04-15T07:01:58.788433612Z: [ERROR] command: {

2025-04-15T07:01:58.788436120Z: [ERROR] name: 'auth',

2025-04-15T07:01:58.788438598Z: [ERROR] args: [ 'red-cvt055q4d50c73daqk60', 'uVV62N7y5RMVGsG3bGEDqNyujtnvAWXD' ]

2025-04-15T07:01:58.788441148Z: [ERROR] }

2025-04-15T07:01:58.788443393Z: [ERROR] }

so to counter this i tried adding the outbound IP Addresses of my backend manually to the redis firewall and i have added all the outbout IP Addresses (i also had this Additional Outbound IP Addresses I didn't add the IP Addresses written under this) but it still gives the same error and the routes dependent on redis fails with the same error in the log stream.
Sampath 3,750 Reputation points Microsoft External Staff Moderator

2025-04-15T10:45:57.0633333+00:00
Hello @Binit Gupta ,

The issue is due Node.js backend is failing to connect to Azure Cache for Redis due to an IP allowlist issue. Here are some steps to troubleshoot and resolve it:

Verify Redis Firewall Settings

Go to Azure Portal → Azure Cache for Redis → Networking.

Check the Firewall rules and ensure your backend’s outbound IP addresses are added.

If your Redis instance is configured for private access, ensure your backend is in the same Virtual Network (VNet).

Use Managed Identity for Secure Access:

Instead of manually adding IPs, consider using Managed Identity for authentication:

Enable Managed Identity for your Azure Web App.

Assign RBAC permissions to allow access to Redis.

Update your Node.js app to use Azure SDK for Redis with Managed Identity.
Binit Gupta 0 Reputation points

2025-04-15T15:57:22.3+00:00

Hello Sampath, I created a Virtual Network and inside this i created a subnet with default settings. Then i created a azure cache for redis with premium plan, and in the network tab i chose virtual network integration with the subnet i created.

now when i am trying to integrate that virtual network with my backend, i am seeing thing as the attached image...

do i need to create a new subnet and simply integrate my backend with it? or is it compulsory that both my redis server and backend should share the same subnet?

UPDATE: I created a new subnet with more size and integrated it with my backend and I tried creating a redis server with that same subnet but it says its not possible... so basically i have a redis server as well as a backend which are connected to the same virtual network but it throws the same error as before.
Sampath 3,750 Reputation points Microsoft External Staff Moderator

2025-04-15T17:59:53.69+00:00
Hello @Binit Gupta ,

No, they do not need to be in the same subnet.But they must be in the same Virtual Network (VNet).

The correct setup is you Need Use Private Endpoint in a subnet (e.g. RedisSubnet) and Use Regional VNet Integration into another subnet (e.g. AppSubnet) of App Service but be in the same VNet .You must have Private DNS zone integrated (Azure usually auto-creates this)

Why Different Subnets?

Redis Private Endpoint requires a dedicated subnet.

App Service VNet Integration (regional) requires its own separate subnet — it cannot share the subnet with the Private Endpoint.

This is by design in Azure networking.

Since you already used the same subnet for Redis and now trying to integrate the backend:

Create a second subnet (example: AppSubnet)

Same VNet as Redis.

Use default settings is fine (no Network Security Group is OK at this point).

Integrate your Web App to AppSubnet:

Go to your Web App → Networking → VNet Integration

Choose the same VNet as Redis and then select the new AppSubnet

That’s it. Now your backend can resolve and connect to the Redis private endpoint via the VNet.

Refer this for below link for configuring an Azure Web App to call Azure Cache for Redis via Private Endpoints

https://github.com/Azure-Samples/web-app-redis-sql-db

You can find more details in the Azure Redis Private Link documentation

Let know if it helped .If you have any other questions, feel free to leave a comment, I'll be happy to help!
Sirra Sneha 550 Reputation points Microsoft External Staff Moderator

2025-04-16T05:22:29.3966667+00:00

Hi @Binit Gupta
Just checking in to see if above information was helpful. If you have any further updates on this issue, please feel free to post back.

Your answer

MarkRuiz-MSFT 0 Reputation points Microsoft Employee

2025-04-13T21:30:47.6433333+00:00

Hi Binit,

Sounds like you already have done this, but I would double check to make sure that your Docker Compose file defines a network that both the Node.js and Redis are part of. That way they can communicate via that defined network.

Can you test the connectivity from a shell inside the Node.js container and try to ping the Redis endpoint? Does that work?

docker exec -it <backend-container-id> sh ping redis

Make sure the correct connection string is being used by your .js app. For example: if you Redis is named "redis", the connection string should like something like redis://redis:6379 Documentation: https://learn.microsoft.com/en-us/azure/azure-cache-for-redis/cache-troubleshoot-connectivity https://learn.microsoft.com/en-us/azure/container-apps/connect-apps
Siva Nair 2,420 Reputation points Microsoft External Staff Moderator

2025-04-14T06:22:21.55+00:00

Hi Binit Gupta,

Ensure proper network configuration and connectivity between your backend and Redis containers

Ensure that your Azure Container App environment is correctly set up to allow inter-container communication. If your application is integrated with a virtual network, confirm that the network settings allow DNS resolution for the Redis container. You may need to check if the Redis container is accessible from the Node.js backend by using the correct service name defined in your Docker Compose file.

Verify that the connection string or environment variable pointing to the Redis service is correctly defined in your Node.js application. The connection string should match the service name used in your Docker Compose file.

Ingress Configuration: If your backend needs to be accessible externally, ensure that the ingress settings are correctly configured. Check that the target port matches the listening port of your Node.js application.

As you got generic "Application Error" Ensure your backend listens on port 80, or set the WEBSITES_PORT App Setting to your container’s internal port (e.g., 3000).Check logs in the Azure Portal under Log Stream or Container Logs for the crash stack trace. Review the logs of both the Node.js backend and the Redis container for any error messages that could provide more insight into the connectivity issue. This can help identify if there are any specific errors related to network access or service resolution.

If you're using Azure Cache for Redis, ensure that your application is configured to connect to the Azure Redis instance rather than a local Redis container. You may need to adjust your connection strings accordingly. azure-cache-for-redis/cache-troubleshoot-connectivity

If you have any further assistant, do let me know.
Binit Gupta 0 Reputation points

2025-04-14T11:30:31.44+00:00

@Siva Nair I don't really have much of a expertise in azure, and i have been looking and searching a lot on youtube and docs but didn't found much, can you help me in detail?

Right now i am thinking this way... I have deployed a Azure cache for redis and then i'll use that connection string in my deployed backend image, will this work?

Also, when i am trying to deploy a azure cache for redis, its not getting deployed and just shows deployment is in progress.
Siva Nair 2,420 Reputation points Microsoft External Staff Moderator

2025-04-15T05:04:07.5933333+00:00

Hi Binit Gupta,

Yes, deploying an Azure Cache for Redis instance and using its connection string in your backend application is a valid and recommended approach.

Retrieve the Redis Connection String-cli-azure-redis

Retrieve the access keys:
az redis list-keys --name <your-redis-name> --resource-group <your-resource-group>

Retrieve the hostname:
az redis show --name <your-redis-name> --resource-group <your-resource-group> --query hostName
Construct the connection string using the retrieved hostname and access key.

As you mentioned Redis deployment is stuck, Use Azure CLI for Deployment:

Sometimes, deploying via CLI can provide more detailed error messages.
az redis create --name <your-redis-name> --resource-group <your-resource-group> --location <location> --sku Basic --vm-size C0

In the Azure Portal, navigate to "Deployments" under your resource group to check for any error messages.cache-monitor-troubleshoot-faq

Ensure your Node.js application is configured to connect to Azure Cache for Redis using the retrieved connection string. Ensure that the host, port, and password match the details from your Azure Redis instance.

Setting Environment Variables in Azure App Service- Under the "Configuration" section, add the following application settings:

Name: REDIS_HOST | Value: <your-redis-hostname>

Name: REDIS_PORT | Value: 6380

Name: REDIS_PASSWORD | Value: <your-access-key>

In your Node.js application, access these variables using process.env

If you have any further assistant, do let me know.
Binit Gupta 0 Reputation points

2025-04-15T07:18:30.1133333+00:00

@Siva Nair i deployed the redis instance as Azure cache for redis and backend as web app.

Inside this i configured the redis string using the hostname and password and it worked in local, i also checked whether my backend docker image is connecting to redis properly or not and it worked on local.

After that i pushed my image to ACR and the deployed the web app. Now my backend is deployed and all the routes which aren't dependent on redis works fine but the routes which uses redis caching fails.

I checked the logs and its having this error:

2025-04-15T07:01:58.788265901Z: [ERROR] 🚨 Redis connection error: ReplyError: Client IP address is not in the allowlist.

2025-04-15T07:01:58.788298971Z: [ERROR] at parseError (/app/node_modules/redis-parser/lib/parser.js:179:12)

2025-04-15T07:01:58.788426467Z: [ERROR] at parseType (/app/node_modules/redis-parser/lib/parser.js:302:14) {

2025-04-15T07:01:58.788433612Z: [ERROR] command: {

2025-04-15T07:01:58.788436120Z: [ERROR] name: 'auth',

2025-04-15T07:01:58.788438598Z: [ERROR] args: [ 'red-cvt055q4d50c73daqk60', 'uVV62N7y5RMVGsG3bGEDqNyujtnvAWXD' ]

2025-04-15T07:01:58.788441148Z: [ERROR] }

2025-04-15T07:01:58.788443393Z: [ERROR] }

so to counter this i tried adding the outbound IP Addresses of my backend manually to the redis firewall and i have added all the outbout IP Addresses (i also had this Additional Outbound IP Addresses I didn't add the IP Addresses written under this) but it still gives the same error and the routes dependent on redis fails with the same error in the log stream.
Sampath 3,750 Reputation points Microsoft External Staff Moderator

2025-04-15T10:45:57.0633333+00:00

Hello @Binit Gupta ,

The issue is due Node.js backend is failing to connect to Azure Cache for Redis due to an IP allowlist issue. Here are some steps to troubleshoot and resolve it:

Verify Redis Firewall Settings

Go to Azure Portal → Azure Cache for Redis → Networking.

Check the Firewall rules and ensure your backend’s outbound IP addresses are added.

If your Redis instance is configured for private access, ensure your backend is in the same Virtual Network (VNet).

Use Managed Identity for Secure Access:

Instead of manually adding IPs, consider using Managed Identity for authentication:

Enable Managed Identity for your Azure Web App.

Assign RBAC permissions to allow access to Redis.

Update your Node.js app to use Azure SDK for Redis with Managed Identity.
Binit Gupta 0 Reputation points

2025-04-15T15:57:22.3+00:00

Hello Sampath, I created a Virtual Network and inside this i created a subnet with default settings. Then i created a azure cache for redis with premium plan, and in the network tab i chose virtual network integration with the subnet i created.

now when i am trying to integrate that virtual network with my backend, i am seeing thing as the attached image...

do i need to create a new subnet and simply integrate my backend with it? or is it compulsory that both my redis server and backend should share the same subnet?

UPDATE: I created a new subnet with more size and integrated it with my backend and I tried creating a redis server with that same subnet but it says its not possible... so basically i have a redis server as well as a backend which are connected to the same virtual network but it throws the same error as before.
Sampath 3,750 Reputation points Microsoft External Staff Moderator

2025-04-15T17:59:53.69+00:00

Hello @Binit Gupta ,

No, they do not need to be in the same subnet.But they must be in the same Virtual Network (VNet).

The correct setup is you Need Use Private Endpoint in a subnet (e.g. RedisSubnet) and Use Regional VNet Integration into another subnet (e.g. AppSubnet) of App Service but be in the same VNet .You must have Private DNS zone integrated (Azure usually auto-creates this)

Why Different Subnets?

Redis Private Endpoint requires a dedicated subnet.

App Service VNet Integration (regional) requires its own separate subnet — it cannot share the subnet with the Private Endpoint.

This is by design in Azure networking.

Since you already used the same subnet for Redis and now trying to integrate the backend:

Create a second subnet (example: AppSubnet)

Same VNet as Redis.

Use default settings is fine (no Network Security Group is OK at this point).

Integrate your Web App to AppSubnet:

Go to your Web App → Networking → VNet Integration

Choose the same VNet as Redis and then select the new AppSubnet

That’s it. Now your backend can resolve and connect to the Redis private endpoint via the VNet.

Refer this for below link for configuring an Azure Web App to call Azure Cache for Redis via Private Endpoints

https://github.com/Azure-Samples/web-app-redis-sql-db

You can find more details in the Azure Redis Private Link documentation

Let know if it helped .If you have any other questions, feel free to leave a comment, I'll be happy to help!
Sirra Sneha 550 Reputation points Microsoft External Staff Moderator

2025-04-16T05:22:29.3966667+00:00

Hi @Binit Gupta
Just checking in to see if above information was helpful. If you have any further updates on this issue, please feel free to post back.

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How to deploy a nodejs REST API backend dependent on redis on Azure?

Why Different Subnets?

Your answer