diff --git a/docs/self-managed/zeebe-deployment/zeebe-gateway/filters.md b/docs/self-managed/zeebe-deployment/zeebe-gateway/filters.md index 7532c58ab8..9e066c89e6 100644 --- a/docs/self-managed/zeebe-deployment/zeebe-gateway/filters.md +++ b/docs/self-managed/zeebe-deployment/zeebe-gateway/filters.md @@ -2,37 +2,38 @@ id: filters title: "Filters" sidebar_label: "Filters" +description: "All communication from a client to a broker must first pass through a gateway. There, it can be filtered before being dispatched." --- :::warning Filters are only applied to the REST API of the gateway, and do not affect any gRPC calls. -For gRPC-related middleware please have read the [Gateway interceptors](interceptors.md) section of the docs. +For gRPC-related middleware, review the [gateway interceptors documentation](interceptors.md). ::: All communication from a client to a broker must first pass through a gateway. -There they can be filtered before being dispatched. Zeebe provides a way to -load arbitrary REST API filters into the gateway. Some typical examples of what you -can accomplish with this include: +There, it can be filtered before being dispatched. + +Zeebe provides a way to load arbitrary REST API filters into the gateway. Some typical examples of what you can accomplish with this include: - Enforcing custom authorization rules on incoming calls -- Monitoring and logging of incoming calls +- Monitoring and logging incoming calls ## Implementing a filter -For the communication between client and gateway, Zeebe uses [REST](components/zeebe/technical-concepts/protocols.md). -A filter is thus implemented as a Jakarta servlet [filter](https://www.javadoc.io/doc/jakarta.servlet/jakarta.servlet-api/6.0.0/jakarta.servlet/jakarta/servlet/Filter.html). +To communicate between client and gateway, Zeebe uses [REST](components/zeebe/technical-concepts/protocols.md). + +A filter is then implemented as a Jakarta servlet [filter](https://www.javadoc.io/doc/jakarta.servlet/jakarta.servlet-api/6.0.0/jakarta.servlet/jakarta/servlet/Filter.html). An implementation must adhere to the following requirements: -- It implements [Filter](https://www.javadoc.io/doc/jakarta.servlet/jakarta.servlet-api/6.0.0/jakarta.servlet/jakarta/servlet/Filter.html) +- It implements a [filter](https://www.javadoc.io/doc/jakarta.servlet/jakarta.servlet-api/6.0.0/jakarta.servlet/jakarta/servlet/Filter.html) - It has public visibility -- It has a public default constructor (i.e. no-arg constructor) +- It has a public default constructor (for example, no-arg constructor) -Let's consider a filter that provides logging of incoming calls as an -example. +Consider a filter logging incoming calls as an example: ```java package io.camunda.zeebe.example; @@ -66,15 +67,15 @@ public final class LoggingFilter implements Filter { } ``` -This example filter will log `"filtered a call"` at `TRACE` level for -each incoming call it filtered. This specific filter always dispatches -all incoming calls to the target broker, but it would also be possible to stop -the message from being filtered by other filters and even to block it from -dispatch to the broker. +This example filter will log `filtered a call` at `TRACE` level for +each incoming call it filters. This specific filter always dispatches +all incoming calls to the target broker, but it is possible to stop +the message from being filtered by other filters, and even block it from +dispatching to the broker. :::note -Camunda 8 relies on [Identity](../../identity/user-guide/tenants/managing-tenants.md) for tenant management and, as of 8.5.0, the REST API part of +Camunda 8 relies on [Identity](../../identity/user-guide/tenants/managing-tenants.md) for tenant management and, as of 8.5.0, the REST API component of the Zeebe Gateway does not support custom tenant-providing filters. ::: @@ -84,11 +85,11 @@ the Zeebe Gateway does not support custom tenant-providing filters. Our source code for the filter class can now be compiled. There are many ways to do this, but for simplicity we'll use `javac` directly. -When compiling your class, you need to make sure all compile-time dependencies -are provided. In the example above, that means we need the `jakarta.servlet-api` and +When compiling your class, ensure all compile-time dependencies +are provided. In the example above, you'll need the `jakarta.servlet-api` and `slf4j-api` libraries available when compiling. -Since the filter will be running inside the Zeebe gateway, the language +Since the filter will be running inside the Zeebe Gateway, the language level of the compiled code must be the same as Zeebe's (i.e. currently JDK 11) or lower. This example thus assumes you're using version 11 of `javac`. ```sh @@ -98,16 +99,15 @@ javac -classpath .:lib/jakarta.servlet-api.jar:lib/slf4j-api.jar ./LoggingFilter ## Packaging a filter -Next, you need to package the filter class into a fat JAR. Such a JAR must -contain all classes (i.e. including all classes your own classes depend upon at +Next, package the filter class into a fat JAR. Such a JAR must +contain all classes (for example, all classes your own classes depend upon at runtime). -Like compiling there are many ways to do this, but for simplicity we'll use -`jar` directly. Note, that means we have to define a java manifest file by hand, -in order to place the libraries' classes on the classpath. +Like compiling, there are many ways to do this, but we'll use +`jar` directly. This means we must define a Java manifest file by hand to place the libraries' classes on the classpath. Similar to your filter class, any libraries you package must be compiled -for the same language level as Zeebe's (i.e. currently JDK 11) or lower. +for the same language level as Zeebe's (currently JDK 11) or lower. :::note @@ -134,21 +134,20 @@ jar tf ./LoggingFilter.jar ## Loading a filter into a gateway A filter can be loaded into your gateway as a fat JAR. For each -filter, you need to provide your gateway with: +filter, provide the gateway with: - A filter order index - An identifier to identify this specific filter - Where to find the JAR with the filter class -- The [fully qualified name](https://docs.oracle.com/javase/specs/jls/se17/html/jls-6.html#jls-6.7) - of the filter class, e.g. `com.acme.ExampleFilter` +- The [fully qualified name](https://docs.oracle.com/javase/specs/jls/se17/html/jls-6.html#jls-6.7) of the filter class. For example, `com.acme.ExampleFilter`. -Let's continue with the `LoggingFilter` example. We can provide these +Continuing with the `LoggingFilter` example, provide these [configurations](/self-managed/zeebe-deployment/configuration/configuration.md) -using a gateway config file, environment variables or a mix of both. We'll be -using a config file here. +using a gateway config file, environment variables, or a mix of both. We'll be +using a config file in this example. The following gateway config file configures our `LoggingFilter` so it can be -loaded into the gateway at start-up. +loaded into the gateway at start-up: ```yaml zeebe: @@ -174,22 +173,22 @@ zeebe: jarPath: ... ``` -Note that multiple filters can be configured (i.e. +:::note +Multiple filters can be configured (for example, `zeebe.gateway.filters` expects a list of filter configurations). The listing order determines the order in which a call is filtered by the different filters. The first filter in the list wraps the second, etc. The first filter is thus the outermost filter. In other words, calls are filtered first by the first listed filter, followed by the second listed filter, etc. +::: -This configuration can also be provided using environment variables. You'll need -to provide an index for the filter in the variable name, to distinguish the +This configuration can also be provided using environment variables. Provide an index for the filter in the variable name to distinguish the ordering of the different filters. For example, to configure the -`className` of the first filter use: -`zeebe_gateway_filters_0_className`. Likewise, a second filter's +`className` of the first filter use `zeebe_gateway_filters_0_className`. Likewise, a second filter's `jarPath` can be configured using `zeebe_gateway_filters_1_jarPath`. -## About class loading +## Class loading [Previously](#packaging-a-filter), we stated that you need to package the filter class into a fat JAR. Although good general advice, this is not @@ -198,57 +197,55 @@ filter works. When your JAR is loaded into the gateway, Zeebe provides a special class loader for it. This class loader isolates your filter from the rest of Zeebe, but -it also exposes our own code to your filter. When loading classes for your -filter, it will always first look in this special class loader and only if -it is not available it will look in Zeebe's main class loader. In other words, +it also exposes our own code to your filter. + +When loading classes for your filter, it will always first look in this special class loader. If +it is not available, it will look in Zeebe's main class loader. Therefore, you can access any classes from Zeebe's main class loader when they are not provided by your JAR. For internal class loading, Zeebe will still only look in its main class loader. -This means you can reduce your JAR size by leaving out libraries that are -already provided by Zeebe's class loader. In addition, if your filter -depends on a different version of a class than the one provided by Zeebe, then -you can provide your own version without having to worry about breaking Zeebe. +You can reduce your JAR size by leaving out libraries already provided by Zeebe's class loader. Additionally, if your filter +depends on a different version of a class than the one provided by Zeebe, you can provide your own version without having to worry about breaking Zeebe. ## Troubleshooting -Here we describe a few common errors. Hopefully, this will help you recognize -these situations and provide an easy fix. Generally, the gateway will not be +Here we describe a few common errors to help you recognize +these situations and provide a solution. Generally, the gateway will not be able to start up with a misconfigured filter. :::note Environment variables can overwrite your gateway configuration file. -The gateway logs the configuration it uses during start-up, use this to +The gateway logs the configuration it uses during start-up; use this to verify your configuration. ::: ### java.lang.ClassNotFoundException Your `Filter` implementation could -not be found. Make sure you've configured the `className` correctly in the -[gateway configuration](#loading-a-filter-into-a-gateway) and that your +not be found. Ensure you've configured the `className` correctly in the +[gateway configuration](#loading-a-filter-into-a-gateway) and your [JAR contains your class](#packaging-a-filter). ### io.camunda.zeebe.gateway.rest.impl.filters.FilterLoadException -Something went wrong trying to load your filter. Make sure your [JAR is -packaged](#packaging-a-filter) correctly, i.e. it contains all runtime +Something went wrong trying to load your filter. Ensure your [JAR is packaged](#packaging-a-filter) correctly. For example, ensure it contains all runtime dependencies and specifies them in the manifest file's classpath. The exception should provide a clear description, but generally we distinguish the following common cases: **\*Unable to instantiate your class** -Make sure your class adheres to the [requirements described above](#implementing-a-filter). +Ensure your class adheres to the [requirements described above](#implementing-a-filter). **The JAR could not be loaded** -Make sure you've configured your filter correctly in the [gateway configuration](#loading-a-filter-into-a-gateway). +Ensure you've configured your filter correctly in the [gateway configuration](#loading-a-filter-into-a-gateway). ### io.camunda.zeebe.util.jar.ExternalJarLoadException -The JAR could not be loaded: make sure you've configured your filter correctly in the [gateway configuration](#loading-a-filter-into-a-gateway). +The JAR could not be loaded. Ensure you've configured your filter correctly in the [gateway configuration](#loading-a-filter-into-a-gateway). ### java.lang.UnsupportedClassVersionError -Your filter has been compiled by a more recent version of the Java Runtime. Make sure your [class is compiled](#packaging-a-filter) with JDK 11. +Your filter has been compiled by a more recent version of the Java Runtime. Ensure your [class is compiled](#packaging-a-filter) with JDK 11. diff --git a/docs/self-managed/zeebe-deployment/zeebe-gateway/interceptors.md b/docs/self-managed/zeebe-deployment/zeebe-gateway/interceptors.md index 98cc31bb0d..4ee364d4d1 100644 --- a/docs/self-managed/zeebe-deployment/zeebe-gateway/interceptors.md +++ b/docs/self-managed/zeebe-deployment/zeebe-gateway/interceptors.md @@ -8,7 +8,7 @@ sidebar_label: "Interceptors" Interceptors are only applied to the gRPC API of the gateway, and do not affect any REST calls. -For REST-related middleware please have read the [Gateway filters](filters.md) section of the docs. +For REST-related middleware, read the [gateway filters documentation](filters.md). :::