HTTP proxy support in Azure Kubernetes Service (AKS)

Article
2025-04-15

In this article, you learn how to configure Azure Kubernetes Service (AKS) clusters to use an HTTP proxy for outbound internet access.

AKS clusters deployed into managed or custom virtual networks have certain outbound dependencies that are necessary to function properly, which created problems in environments requiring internet access to be routed through HTTP proxies. Nodes had no way of bootstrapping the configuration, environment variables, and certificates necessary to access internet services.

The HTTP proxy feature adds HTTP proxy support to AKS clusters, exposing a straightforward interface that you can use to secure AKS-required network traffic in proxy-dependent environments. With this feature, both AKS nodes and pods are configured to use the HTTP proxy. The feature also enables installation of a trusted certificate authority onto the nodes as part of bootstrapping a cluster. More complex solutions might require creating a chain of trust to establish secure communications across the network.

Limitations and considerations

The following scenarios are not supported:

Different proxy configurations per node pool
User/Password authentication
Custom certificate authorities (CAs) for API server communication
AKS clusters with Windows node pools
Node pools using Virtual Machine Availability Sets (VMAS)
Using * as wildcard attached to a domain suffix for noProxy

httpProxy, httpsProxy, and trustedCa have no value by default. Pods are injected with the following environment variables:

HTTP_PROXY
http_proxy
HTTPS_PROXY
https_proxy
NO_PROXY
no_proxy

To disable the injection of the proxy environment variables, you need to annotate the Pod with "kubernetes.azure.com/no-http-proxy-vars":"true".

Before you begin

You need the latest version of the Azure CLI. Run az --version to find the version, and run az upgrade to upgrade the version. If you need to install or upgrade, see Install Azure CLI.
Check for available AKS cluster upgrades to ensure you're running the latest version of AKS. If you need to upgrade, see Upgrade an AKS cluster.

You can configure an AKS cluster with an HTTP proxy during cluster creation using the az aks create command and passing in configuration as a JSON file.

Create a file and provide values for httpProxy, httpsProxy, and noProxy. If your environment requires it, provide a value for trustedCa.

The schema for the config file looks like this:

{
  "httpProxy": "string",
  "httpsProxy": "string",
  "noProxy": [
    "string"
  ],
  "trustedCa": "string"
}

Review requirements for each parameter:

httpProxy: A proxy URL to use for creating HTTP connections outside the cluster. The URL scheme must be http.
httpsProxy: A proxy URL to use for creating HTTPS connections outside the cluster. If not specified, then httpProxy is used for both HTTP and HTTPS connections.
noProxy: A list of destination domain names, domains, IP addresses, or other network CIDRs to exclude proxying.
trustedCa: A string containing the base64 encoded alternative CA certificate content. Currently only the PEM format is supported.

Important

For compatibility with Go-based components that are part of the Kubernetes system, the certificate must support Subject Alternative Names(SANs) instead of the deprecated Common Name certs.

There are differences in applications on how to comply with the environment variable http_proxy, https_proxy, and no_proxy. Curl and Python don't support CIDR in no_proxy, but Ruby does.

Example input:

{
  "httpProxy": "http://myproxy.server.com:8080/", 
  "httpsProxy": "https://myproxy.server.com:8080/", 
  "noProxy": [
    "localhost",
    "127.0.0.1"
  ],
  "trustedCA": "LS0tLS1CRUdJTiBDRVJUSUZJQ0FURS0tLS0tCk1JSUgvVENDQmVXZ0F3SUJB...b3Rpbk15RGszaWFyCkYxMFlscWNPbWVYMXVGbUtiZGkvWG9yR2xrQ29NRjNURHg4cm1wOURCaUIvCi0tLS0tRU5EIENFUlRJRklDQVRFLS0tLS0="
}

Create a cluster using the az aks create command with the --http-proxy-config parameter set to the file you created.

az aks create \
    --name $clusterName \
    --resource-group $resourceGroup \
    --http-proxy-config aks-proxy-config.json \
    --generate-ssh-keys

Your cluster should initialize with the HTTP proxy configured on the nodes.

You can deploy an AKS cluster with an HTTP proxy using an ARM template.

In your template, provide values for httpProxy, httpsProxy, and noProxy. If necessary, provide a value for trustedCa.

The same schema used for CLI deployment exists in the Microsoft.ContainerService/managedClusters definition under "properties", as shown in the following example:

"properties": {
    ...,
    "httpProxyConfig": {
        "httpProxy": "string",
        "httpsProxy": "string",
        "noProxy": [
            "string"
        ],
        "trustedCa": "string"
    }
}

Deploy your ARM template with the HTTP Proxy configuration

Next, you can deploy the template. Your cluster should initialize with your HTTP proxy configured on the nodes.

If you are using the Istio-based service mesh add-on for AKS, you must create a Service Entry to enable your applications in the mesh to access non-cluster or external resources via the HTTP proxy. For example:

apiVersion: networking.istio.io/v1
kind: ServiceEntry
metadata:
  name: proxy
spec:
  hosts:
  - my-company-proxy.com # ignored
  addresses:
  - $PROXY_IP/32
  ports:
  - number: $PROXY_PORT
    name: tcp
    protocol: TCP
  location: MESH_EXTERNAL

Create a file and provide values for PROXY_IP and PROXY_PORT.
You can deploy the Service Entry using:

kubectl apply -f service_proxy.yaml

Update cluster to enable or update http proxy configuration

Note

If switching to a new proxy, the new proxy must already exist for the update to be successful. After the upgrade is completed, you can delete the old proxy.

HTTP Proxy configuration can be enabled or updated on an existing cluster using the az aks update command. The --http-proxy-config parameter should be set to a new JSON file with updated values for httpProxy, httpsProxy, noProxy, and trustedCa if necessary. The update injects new environment variables into pods with the new httpProxy, httpsProxy, or noProxy values.

Caution

AKS will automatically reimage all node pools in the cluster when you update the proxy configuration on your cluster using the az aks update command. You can use Pod Disruption Budgets (PDBs) to safeguard disruption to critical pods during reimage.

For example, let's say you created a new file with the base64 encoded string of the new CA cert called aks-proxy-config-2.json. You can update the proxy configuration on your cluster with the following command:

az aks update --name $clusterName --resource-group $resourceGroup --http-proxy-config aks-proxy-config-2.json

Monitoring add-on configuration

HTTP proxy with the monitoring add-on supports the following configurations:

Outbound proxy without authentication
Outbound proxy with username & password authentication
Outbound proxy with trusted cert for Log Analytics endpoint

The following configurations aren't supported:

Custom Metrics and Recommended Alerts features when using a proxy with trusted certificates

Next steps

For more information regarding the network requirements of AKS clusters, see Control egress traffic for cluster nodes in AKS.

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