Tutorial: Connect to a managed Gateway for Spring in Azure Container Apps (preview)

Article
11/19/2024

Gateway for Spring offers an efficient and powerful way to route, manage and handle API requests as part of a microservices architecture. It serves as an API Gateway that routes external requests to different services, adding various capabilities such as filtering, load balancing, and more. In this article, you learn how to create a gateway that directs requests to your container apps.

In this tutorial, you learn to:

Create a Gateway for Spring Java component
Update the gateway for spring with custom routes to redirect requests to container apps

Important

This tutorial uses services that can affect your Azure bill. If you decide to follow along step-by-step, make sure you delete the resources featured in this article to avoid unexpected billing.

Prerequisites

An Azure account with an active subscription. If you don't already have one, you can can create one for free.
Azure CLI.

Considerations

When running in Gateway for Spring in Azure Container Apps, be aware of the following details:

Item	Explanation
Scope	The Gateway for Spring runs in the same environment as the connected container app.
Resources	The container resource allocation for Gateway for Spring is fixed, the number of the CPU cores is 0.5, and the memory size is 1Gi.
Pricing	The Gateway for Spring billing falls under consumption-based pricing. Resources consumed by managed Java components are billed at the active/idle rates. You may delete components that are no longer in use to stop billing.

Setup

Before you begin to work with the Gateway for Spring, you first need to create the required resources.

Execute the following commands to create your resource group and Container Apps environment.

Create variables to support your application configuration. These values are provided for you for the purposes of this lesson. We use the actuator endpoint of admin for spring sample app in this lesson.

export LOCATION=eastus
export RESOURCE_GROUP=my-spring-cloud-resource-group
export ENVIRONMENT=my-spring-cloud-environment
export JAVA_COMPONENT_NAME=mygateway
export APP_NAME=myapp
export IMAGE="mcr.microsoft.com/javacomponents/samples/sample-admin-for-spring-client:latest"

Variable	Description
`LOCATION`	The Azure region location where you create your container app and Java component.
`ENVIRONMENT`	The Azure Container Apps environment name for your demo application.
`RESOURCE_GROUP`	The Azure resource group name for your demo application.
`JAVA_COMPONENT_NAME`	The name of the Java component created for your container app. In this case, you create a Gateway for Spring Java component.
`IMAGE`	The container image used in your container app.

Create a resource group.

az group create --name $RESOURCE_GROUP --location $LOCATION

Create your container apps environment.
```
az containerapp env create \
    --name $ENVIRONMENT \
    --resource-group $RESOURCE_GROUP \
    --location $LOCATION
```
This environment is used to host both the Gateway for Spring component and your container app.

Use the Gateway for Spring Java component

Now that you have a Container Apps environment, you can create your container app use a gateway for spring java components to route request to them.

Create the Gateway for Spring Java component.

az containerapp env java-component gateway-for-spring create \
    --environment $ENVIRONMENT \
    --resource-group $RESOURCE_GROUP \
    --name $JAVA_COMPONENT_NAME \

Create the container app that has the fully qualified domain name (FQDN).

az containerapp create \
    --name $APP_NAME \
    --resource-group $RESOURCE_GROUP \
    --environment $ENVIRONMENT \
    --image $IMAGE \
    --ingress external \
    --target-port 8080 \
    --query properties.configuration.ingress.fqdn

This command returns the URL of your container app that consumes configuration data. Copy the URL to a text editor so you can use it in next step.

Update the Gateway Routes to route requests

Create a YAML file with the following content. Replace <MYAPP_URL> with the container app FQDN from the previous step.

springCloudGatewayRoutes:
- id: "route1"
  uri: "<MYAPP_URL>"
  predicates:
    - "Path=/myapp/{path}"
  filters:
    - "SetPath=/actuator/{path}"

Run the following command to update the Gateway for Spring component with your route configuration.
```
az containerapp env java-component gateway-for-spring update \
    --environment $ENVIRONMENT \
    --resource-group $RESOURCE_GROUP \
    --name $JAVA_COMPONENT_NAME \ 
    --route-yaml <PTAH_TO_ROUTE_YAML_FILE> \
    --query properties.ingress.fqdn
```
This command updates the gateway route and returns the URL of your gateway that consumes configuration data.

The command returns the gateway's URL. Visiting this URL with the path /myapp/health should route the request to your app's actuator/health endpoint, returning {"status":"UP","groups":["liveness","readiness"]}.

Clean up resources

The resources created in this tutorial have an effect on your Azure bill. If you aren't going to use these services long-term, run the following command to remove everything created in this tutorial.

az group delete --resource-group $RESOURCE_GROUP

Route file format

The Gateway for Spring component supports defining routes through properties with ID, URI, predicates, and filters. For more information, see the Spring Cloud Gateway documentation. Following is an example YAML file that demonstrates how to configure these properties.

  springCloudGatewayRoutes:
  - id: "route1"
    uri: "https://otherjavacomponent.myenvironment.test.net"
    predicates:
      - "Path=/v1/{path}"
      - "After=2024-01-01T00:00:00.000-00:00[America/Denver]"
    filters:
      - "SetPath=/{path}"
  - id: "route2"
    uri: "https://otherjavacomponent.myenvironment.test.net"
    predicates:
      - "Path=/v2/{path}"
      - "After=2024-01-01T00:00:00.000-00:00[America/Denver]"
    filters:
      - "SetPath=/{path}"

Allowed configuration list for your Gateway for Spring(#configurable-properties)

The following table describes the gateway component properties you can configure for your app. For more information, see Spring Cloud Gateway Common application properties.

Property name	Description	Default value
`spring.cloud.gateway.default-filters`	List of filter definitions that are applied to every route.
`spring.cloud.gateway.enabled`	Enables gateway functionality.	`true`
`spring.cloud.gateway.fail-on-route-definition-error`	Option to fail on route definition errors, defaults to true. Otherwise, a warning is logged.	`true`
`spring.cloud.gateway.handler-mapping.order`	The order of `RoutePredicateHandlerMapping`.	`1`
`spring.cloud.gateway.loadbalancer.use404`		`false`
`spring.cloud.gateway.discovery.locator.enabled`	Flag that enables `DiscoveryClient` gateway integration.	`false`
`spring.cloud.gateway.discovery.locator.filters`
`spring.cloud.gateway.discovery.locator.include-expression`	SpEL expression that evaluates whether to include a service in gateway integration or not. The default value is `true`.	`true`
`spring.cloud.gateway.discovery.locator.lower-case-service-id`	Option to lower case `serviceId` in predicates and filters. The default value is `false`. Useful with Eureka when it automatically uppercases `serviceId`. So, `MYSERVICE` would match `/myservice/**`	`false`
`spring.cloud.gateway.discovery.locator.predicates`
`spring.cloud.gateway.discovery.locator.route-id-prefix`	The prefix for the `routeId`, defaults to `discoveryClient.getClass().getSimpleName()` + "_". Service ID is appended to create the `routeId`.
`spring.cloud.gateway.discovery.locator.url-expression`	SpEL expression that creates the URI for each route. The default value is `'lb://'+serviceId`.	`'lb://'+serviceId`
`spring.cloud.gateway.filter.add-request-header.enabled`	Enables the `add-request-header` filter.	`true`
`spring.cloud.gateway.filter.add-request-parameter.enabled`	Enables the `add-request-parameter` filter.	`true`
`spring.cloud.gateway.filter.add-response-header.enabled`	Enables the `add-response-header` filter.	`true`
`spring.cloud.gateway.filter.circuit-breaker.enabled`	Enables the `circuit-breaker` filter.	`true`
`spring.cloud.gateway.filter.dedupe-response-header.enabled`	Enables the `dedupe-response-header` filter.	`true`
`spring.cloud.gateway.filter.fallback-headers.enabled`	Enables the `fallback-headers` filter.	`true`
`spring.cloud.gateway.filter.hystrix.enabled`	Enables the `hystrix` filter.	`true`
`spring.cloud.gateway.filter.json-to-grpc.enabled`	Enables the JSON to gRPC filter.	`true`
`spring.cloud.gateway.filter.local-response-cache.enabled`	Enables the `local-response-cache` filter.	`false`
`spring.cloud.gateway.filter.local-response-cache.request.no-cache-strategy`
`spring.cloud.gateway.filter.local-response-cache.size`	Maximum size of the cache to evict entries for this route in KB, MB, and GB.
`spring.cloud.gateway.filter.local-response-cache.time-to-live`	Time to expire a cache entry, expressed in `s` for seconds, `m` for minutes, and `h` for hours.	`5m`
`spring.cloud.gateway.filter.map-request-header.enabled`	Enables the `map-request-header` filter.	`true`
`spring.cloud.gateway.filter.modify-request-body.enabled`	Enables the `modify-request-body` filter.	`true`
`spring.cloud.gateway.filter.modify-response-body.enabled`	Enables the `modify-response-body` filter.	`true`
`spring.cloud.gateway.filter.prefix-path.enabled`	Enables the `prefix-path` filter.	`true`
`spring.cloud.gateway.filter.preserve-host-header.enabled`	Enables the `preserve-host-header` filter.	`true`
`spring.cloud.gateway.filter.redirect-to.enabled`	Enables the `redirect-to` filter.	`true`
`spring.cloud.gateway.filter.remove-hop-by-hop.headers`
`spring.cloud.gateway.filter.remove-hop-by-hop.order`		`0`
`spring.cloud.gateway.filter.remove-request-header.enabled`	Enables the `remove-request-header` filter.	`true`
`spring.cloud.gateway.filter.remove-request-parameter.enabled`	Enables the `remove-request-parameter` filter.	`true`
`spring.cloud.gateway.filter.remove-response-header.enabled`	Enables the `remove-response-header` filter.	`true`
`spring.cloud.gateway.filter.request-header-size.enabled`	Enables the `request-header-size` filter.	`true`
`spring.cloud.gateway.filter.request-header-to-request-uri.enabled`	Enables the `request-header-to-request-uri` filter.	`true`
`spring.cloud.gateway.filter.request-rate-limiter.default-key-resolver`
`spring.cloud.gateway.filter.request-rate-limiter.default-rate-limiter`
`spring.cloud.gateway.filter.request-rate-limiter.enabled`	Enables the `request-rate-limiter` filter.	`true`
`spring.cloud.gateway.filter.request-size.enabled`	Enables the `request-size` filter.	`true`
`spring.cloud.gateway.filter.retry.enabled`	Enables the `retry` filter.	`true`
`spring.cloud.gateway.filter.rewrite-location-response-header.enabled`	Enables the `rewrite-location-response-header` filter.	`true`
`spring.cloud.gateway.filter.rewrite-location.enabled`	Enables the `rewrite-location` filter.	`true`
`spring.cloud.gateway.filter.rewrite-path.enabled`	Enables the `rewrite-path` filter.	`true`
`spring.cloud.gateway.filter.rewrite-request-parameter.enabled`	Enables the `rewrite-request-parameter` filter.	`true`
`spring.cloud.gateway.filter.rewrite-response-header.enabled`	Enables the `rewrite-response-header` filter.	`true`
`spring.cloud.gateway.filter.save-session.enabled`	Enables the `save-session` filter.	`true`
`spring.cloud.gateway.filter.secure-headers.content-security-policy`		`default-src 'self' https:; font-src 'self' https: data:; img-src 'self' https: data:; object-src 'none'; script-src https:; style-src 'self' https: 'unsafe-inline'`
`spring.cloud.gateway.filter.secure-headers.content-type-options`		`nosniff`
`spring.cloud.gateway.filter.secure-headers.disable`
`spring.cloud.gateway.filter.secure-headers.download-options`		`noopen`
`spring.cloud.gateway.filter.secure-headers.enabled`	Enables the `secure-headers` filter.	`true`
`spring.cloud.gateway.filter.secure-headers.frame-options`		`DENY`
`spring.cloud.gateway.filter.secure-headers.permitted-cross-domain-policies`		`none`
`spring.cloud.gateway.filter.secure-headers.referrer-policy`		`no-referrer`
`spring.cloud.gateway.filter.secure-headers.strict-transport-security`		`max-age=631138519`
`spring.cloud.gateway.filter.secure-headers.xss-protection-header`		`1 ; mode=block`
`spring.cloud.gateway.filter.set-path.enabled`	Enables the `set-path` filter.	`true`
`spring.cloud.gateway.filter.set-request-header.enabled`	Enables the `set-request-header` filter.	`true`
`spring.cloud.gateway.filter.set-request-host-header.enabled`	Enables the `set-request-host-header` filter.	`true`
`spring.cloud.gateway.filter.set-response-header.enabled`	Enables the `set-response-header` filter.	`true`
`spring.cloud.gateway.filter.set-status.enabled`	Enables the `set-status` filter.	`true`
`spring.cloud.gateway.filter.strip-prefix.enabled`	Enables the `strip-prefix` filter.	`true`
`spring.cloud.gateway.forwarded.enabled`	Enables the `ForwardedHeadersFilter`.	`true`
`spring.cloud.gateway.global-filter.adapt-cached-body.enabled`	Enables the `adapt-cached-body` global filter.	`true`
`spring.cloud.gateway.global-filter.forward-path.enabled`	Enables the `forward-path` global filter.	`true`
`spring.cloud.gateway.global-filter.forward-routing.enabled`	Enables the `forward-routing` global filter.	`true`
`spring.cloud.gateway.global-filter.load-balancer-client.enabled`	Enables the `load-balancer-client` global filter.	`true`
`spring.cloud.gateway.global-filter.local-response-cache.enabled`	Enables the `local-response-cache` filter for all routes, which enables you to add a specific configuration at the route level using a `LocalResponseCache` filter.	`true`
`spring.cloud.gateway.global-filter.netty-routing.enabled`	Enables the `netty-routing global` filter.	`true`
`spring.cloud.gateway.global-filter.netty-write-response.enabled`	Enables the `netty-write-response` global filter.	`true`
`spring.cloud.gateway.global-filter.reactive-load-balancer-client.enabled`	Enables the `reactive-load-balancer-client` global filter.	`true`
`spring.cloud.gateway.global-filter.remove-cached-body.enabled`	Enables the `remove-cached-body` global filter.	`true`
`spring.cloud.gateway.global-filter.route-to-request-url.enabled`	Enables the `route-to-request-url` global filter.	`true`
`spring.cloud.gateway.global-filter.websocket-routing.enabled`	Enables the `websocket-routing` global filter.	`true`
`spring.cloud.gateway.globalcors.add-to-simple-url-handler-mapping`	If global CORS config should be added to the URL handler.	`false`
`spring.cloud.gateway.globalcors.cors-configurations`
`spring.cloud.gateway.redis-rate-limiter.burst-capacity-header`	The name of the header that returns the burst capacity configuration.	`X-RateLimit-Burst-Capacity`
`spring.cloud.gateway.redis-rate-limiter.config`
`spring.cloud.gateway.redis-rate-limiter.include-headers`	Whether or not to include headers containing rate limiter information. The default value is `true`.	`true`
`spring.cloud.gateway.redis-rate-limiter.remaining-header`	The name of the header that returns number of remaining requests during the current second.	`X-RateLimit-Remaining`
`spring.cloud.gateway.redis-rate-limiter.replenish-rate-header`	The name of the header that returns the replenish rate configuration.	`X-RateLimit-Replenish-Rate`
`spring.cloud.gateway.redis-rate-limiter.requested-tokens-header`	The name of the header that returns the requested tokens configuration.	`X-RateLimit-Requested-Tokens`
`spring.cloud.gateway.restrictive-property-accessor.enabled`	Restricts method and property access in SpEL.	`true`
`spring.cloud.gateway.predicate.after.enabled`	Enables the `after` predicate.	`true`
`spring.cloud.gateway.predicate.before.enabled`	Enables the `before` predicate.	`true`
`spring.cloud.gateway.predicate.between.enabled`	Enables the `between` predicate.	`true`
`spring.cloud.gateway.predicate.cloud-foundry-route-service.enabled`	Enables the `cloud-foundry-route-service` predicate.	`true`
`spring.cloud.gateway.predicate.cookie.enabled`	Enables the `cookie` predicate.	`true`
`spring.cloud.gateway.predicate.header.enabled`	Enables the `header` predicate.	`true`
`spring.cloud.gateway.predicate.host.enabled`	Enables the `host` predicate.	`true`
`spring.cloud.gateway.predicate.host.include-port`	Include the port in matching the host name.	`true`
`spring.cloud.gateway.predicate.method.enabled`	Enables the `method` predicate.	`true`
`spring.cloud.gateway.predicate.path.enabled`	Enables the `path` predicate.	`true`
`spring.cloud.gateway.predicate.query.enabled`	Enables the `query` predicate.	`true`
`spring.cloud.gateway.predicate.read-body.enabled`	Enables the `read-body` predicate.	`true`
`spring.cloud.gateway.predicate.remote-addr.enabled`	Enables the `remote-addr` predicate.	`true`
`spring.cloud.gateway.predicate.weight.enabled`	Enables the `weight` predicate.	`true`
`spring.cloud.gateway.predicate.xforwarded-remote-addr.enabled`	Enables the `xforwarded-remote-addr` predicate.	`true`
`spring.cloud.gateway.set-status.original-status-header-name`	The name of the header which contains the HTTP code of the proxied request.
`spring.cloud.gateway.streaming-media-types`
`spring.cloud.gateway.x-forwarded.enabled`	If the `XForwardedHeadersFilter` is enabled.	`true`
`spring.cloud.gateway.x-forwarded.for-append`	If appending `X-Forwarded-For` as a list is enabled.	`true`
`spring.cloud.gateway.x-forwarded.for-enabled`	If `X-Forwarded-For` is enabled.	`true`
`spring.cloud.gateway.x-forwarded.host-append`	If appending `X-Forwarded-Host` as a list is enabled.	`true`
`spring.cloud.gateway.x-forwarded.host-enabled`	If `X-Forwarded-Host` is enabled.	`true`
`spring.cloud.gateway.x-forwarded.order`	The order of the `XForwardedHeadersFilter`.	`0`
`spring.cloud.gateway.x-forwarded.port-append`	If appending `X-Forwarded-Port` as a list is enabled.	`true`
`spring.cloud.gateway.x-forwarded.port-enabled`	If `X-Forwarded-Port` is enabled.	`true`
`spring.cloud.gateway.x-forwarded.prefix-append`	If appending `X-Forwarded-Prefix` as a list is enabled.	`true`
`spring.cloud.gateway.x-forwarded.prefix-enabled`	If `X-Forwarded-Prefix` is enabled.	`true`
`spring.cloud.gateway.x-forwarded.proto-append`	If appending `X-Forwarded-Proto` as a list is enabled.	`true`
`spring.cloud.gateway.x-forwarded.proto-enabled`	If `X-Forwarded-Proto` is enabled.	`true`
`spring.cloud.gateway.httpclient.compression`	Enables compression for Netty `HttpClient`.	`false`
`spring.cloud.gateway.httpclient.connect-timeout`	The connected timeout in millis. The default value is `30s`.
`spring.cloud.gateway.httpclient.max-header-size`	The max response header size.
`spring.cloud.gateway.httpclient.max-initial-line-length`	The max initial line length.
`spring.cloud.gateway.httpclient.pool.acquire-timeout`	Only for type `FIXED`, the maximum time in millis to wait for acquiring.
`spring.cloud.gateway.httpclient.pool.eviction-interval`	Perform regular eviction checks in the background at a specified interval. Disabled by default (`{@link Duration#ZERO}`).	`0`
`spring.cloud.gateway.httpclient.pool.max-connections`	Only for type FIXED, the maximum number of connections before starting pending acquisition on existing ones.
`spring.cloud.gateway.httpclient.pool.max-idle-time`	Time in millis after which the channel is closed. If `NULL`, there's no max idle time.
`spring.cloud.gateway.httpclient.pool.max-life-time`	Duration after which the channel is closed. If `NULL`, there's no max life time.
`spring.cloud.gateway.httpclient.pool.metrics`	Enables channel pools metrics to be collected and registered in Micrometer. Disabled by default.	`false`
`spring.cloud.gateway.httpclient.pool.name`	The channel pool map name, defaults to proxy.	`proxy`
`spring.cloud.gateway.httpclient.pool.type`	Type of pool for `HttpClient` to use, defaults to `ELASTIC`.
`spring.cloud.gateway.httpclient.response-timeout`	The response timeout.
`spring.cloud.gateway.httpclient.ssl.close-notify-flush-timeout`	SSL `close_notify` flush timeout. The default value `3000 ms`.	`3000ms`
`spring.cloud.gateway.httpclient.ssl.close-notify-read-timeout`	SSL `close_notify` read timeout. The default value is `0 ms`.	`0`
`spring.cloud.gateway.httpclient.ssl.handshake-timeout`	SSL handshake timeout. The default value is `10000 ms.`	`10000ms`
`spring.cloud.gateway.httpclient.ssl.use-insecure-trust-manager`	Installs the netty `InsecureTrustManagerFactory`. This is insecure and isn't suitable for production.	`false`
`spring.cloud.gateway.httpclient.websocket.max-frame-payload-length`	Max frame payload length.
`spring.cloud.gateway.httpclient.websocket.proxy-ping`	Proxy ping frames to downstream services. The default value is `true`.	`true`
`spring.cloud.gateway.httpclient.wiretap`	Enables wiretap debugging for Netty `HttpClient`.	`false`
`spring.cloud.gateway.httpserver.wiretap`	Enables wiretap debugging for Netty `HttpServer`.	`false`
`spring.cloud.gateway.metrics.enabled`	Enables the collection of metrics data.	`false`
`spring.cloud.gateway.metrics.prefix`	The prefix of all metrics emitted by gateway.	`spring.cloud.gateway`
`spring.cloud.gateway.metrics.tags`	Tags map that added to metrics.
`spring.cloud.gateway.observability.enabled`	If Micrometer Observability support should be turned on.	`true`

Common configurations

The following list describes common configurations:

Logging related configurations:
- logging.level.*
- logging.group.*
- Any other configurations under logging.* namespace should be forbidden. For example, writing log files by using logging.file should be forbidden.

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