--- title: Kubernetes Agent + Module summary: null url: >- https://www.fastly.com/documentation/guides/next-gen-waf/setup-and-configuration/kubernetes/kubernetes-agent-module --- In this example, the Next-Gen WAF agent is deployed in a docker sidecar, communicating with a module deployed on the application. ## Integrating the Next-Gen WAF agent The Next-Gen WAF agent can be installed as a sidecar into each pod or as a service for some specialized needs. The recommended way of installing the Next-Gen WAF agent in Kubernetes is by integrating the `sigsci-agent` into a pod as a [sidecar](https://matthewpalmer.net/kubernetes-app-developer/articles/multi-container-pod-design-patterns.html). This means adding the `sigsci-agent` as an additional container to the Kubernetes pod. As a sidecar, the agent will scale with the app/service in the pod instead of having to do this separately. However, in some situations, it may make more sense to install the `sigsci-agent` container as a service and [scale it separately from the application](https://www.fastly.com/documentation/guides/next-gen-waf/setup-and-configuration/kubernetes/kubernetes-agent-scaling). The `sigsci-agent` container can be configured in various ways depending on the installation type and module being used. You can use the [`preStop` container hook](https://kubernetes.io/docs/concepts/containers/container-lifecycle-hooks/#container-hooks) to slow the pod's shutdown and ensure drain timeouts are met. ```yaml preStop: exec: command: - sleep - "30" ``` By default, the agent prioritizes quick start up and performance readiness for preliminary inspection. However, quick startup isn't always desirable if you only want the agent to inspect traffic after loading your rules and configuration data. If you want to delay agent startup, consider configuring a [startup probe](https://www.fastly.com/documentation/guides/next-gen-waf/setup-and-configuration/kubernetes/kubernetes-startup-probe). ## Getting and updating the agent container image An official `signalsciences/sigsci-agent` container image is available on [Docker Hub](https://hub.docker.com/r/signalsciences/sigsci-agent). We also provide an official `signalsciences/sigsci-agent-slim `container image, which contains just the sigsci-agent without all of the dependencies of the regular sigsci-agent container image. It is also available on [Docker Hub](https://hub.docker.com/r/signalsciences/sigsci-agent-slim). Using it is identical to using the regular sigsci-agent container image, but you will have difficulty debugging the image if necessary. Alternatively, if you want to build your own image or need to customize the image, then follow the [sigsci-agent build instructions](https://www.fastly.com/documentation/guides/next-gen-waf/setup-and-configuration/kubernetes/kubernetes-agent). These instructions reference the `latest` version of the agent with `imagePullPolicy: Always`, which will pull the latest agent version even if one already exist locally. This is so the documentation does not fall out of date and anyone using this will not have an agent that stays stagnant. However, this may not suit your needs if you need to keep installations consistent or on a specific version of the agent. In these cases, you should specify an [agent version](https://www.fastly.com/documentation/reference/changes/ngwaf-agent/). Images on Docker Hub are tagged with their versions and [a list of versions is available on Docker Hub](https://hub.docker.com/r/signalsciences/sigsci-agent/tags). Whether you choose to use the `latest` image or a specific version, there are a few items to consider to keep the agent up-to-date. ### Using the `latest` container image If you do choose to use the `latest` image, then you will want to consider how you will keep the agent up to date. - If you have used the `imagePullPolicy: Always` option, then the latest image will be pulled on each startup and your agent will continue to get updates. - Alternatively, you may instead choose to manually update the local cache by periodically forcing a pull instead of always pulling on startup: ```term copy $ docker pull signalsciences/sigsci-agent:latest ``` Then, use `latest` with `imagePullPolicy: Never` set in the configuration so that pulls are never done on startup (only manually as above): ```yaml - name: sigsci-agent image: signalsciences/sigsci-agent:latest imagePullPolicy: Never ... ``` ### Using a versioned container image To use a specific version of the agent, replace `latest` with the agent version (represented here by `x.xx.x`). You may also want to change `imagePullPolicy: IfNotPresent` in this case as the image should not change. ```yaml - name: sigsci-agent image: signalsciences/sigsci-agent:x.xx.x imagePullPolicy: IfNotPresent ... ``` This will pull the specified agent version and cache it locally. If you use this method, then it is recommended that you parameterize the agent image, using Helm or similar, so that it is easier to update the agent images later on. ### Using a custom tag for the container image It is also possible to apply a custom tag to a local agent image. To do this, pull the agent image (by version or use `latest`), apply a custom tag, then use that custom tag in the configuration. You will need to specify `imagePullPolicy: Never` so local images are only updated manually. After doing so, you will need to periodically update the local image to keep the agent up-to-date. For example: ```term copy nolinenums $ docker pull signalsciences/sigsci-agent:latest $ docker tag signalsciences/sigsci-agent:latest signalsciences/sigsci-agent:testing ``` Then use this image tag in the configuration: ```yaml - name: sigsci-agent image: signalsciences/sigsci-agent:testing imagePullPolicy: Never ... ``` ## Configuring the agent container Agent configuration is normally done via the environment. Most configuration options are available as environment variables. Environment variables names have the configuration option name all capitalized, prefixed with `SIGSCI_` and any dashes (-) changed to underscores (\_). For example, the [max-procs](https://www.fastly.com/documentation/reference/ngwaf/agent-config/#agentcfg_max-procs) option would become the `SIGSCI_MAX_PROCS` environment variable. For more details on what options are available, see the [Agent Configuration documentation](https://www.fastly.com/documentation/reference/ngwaf/agent-config). The `sigsci-agent` container has a few required options that need to be configured: - Agent credentials (**Agent Access Key** and **Agent Secret Key**). - A volume to write temporary files. ### Agent credentials The [`sigsci-agent` credentials](https://www.fastly.com/documentation/guides/next-gen-waf/setup-and-configuration/agent-management/accessing-agent-keys) are configured with two environment variables. These variables must be set or the agent will not start. - **SIGSCI_ACCESSKEYID**: The **Agent Access Key** identifies which site (also known as workspace) the agent is configured for. - **SIGSCI_SECRETACCESSKEY**: The **Agent Secret Key** is the shared secret key to authenticate and authorize the agent. Because of the sensitive nature of these values, we recommend you use the built in `secrets` functionality of Kubernetes. With this configuration, the agent will pull the values from the secrets data instead of reading hardcoded values into the deployment configuration. This also makes any desired agent credential rotation easier to manage by having to change them in only one place. Use the `valueFrom` option instead of the `value` option to use the `secrets` functionality. For example: ```yaml env: - name: SIGSCI_ACCESSKEYID valueFrom: secretKeyRef: # Update my-site-name-here to the correct site (workspace) name or similar identifier name: sigsci.my-site-name-here key: accesskeyid - name: SIGSCI_SECRETACCESSKEY valueFrom: secretKeyRef: # Update my-site-name-here to the correct site (workspace) name or similar identifier name: sigsci.my-site-name-here key: secretaccesskey ``` The `secrets` functionality keeps secrets in various stores in Kubernetes. This guide uses the generic secret store in its examples, however any equivalent store can be used. Agent secrets can be added to the generic secret store using YAML similar to the following example: ```yaml apiVersion: v1 kind: Secret metadata: name: sigsci.my-site-name-here stringData: accesskeyid: 12345678-abcd-1234-abcd-1234567890ab secretaccesskey: abcdefg_hijklmn_opqrstuvwxy_z0123456789ABCD ``` This can also be created from the command line with `kubectl` such as with the following example: ```term copy nolinenums $ kubectl create secret generic sigsci.my-site-name-here \ --from-literal=accesskeyid=12345678-abcd-1234-abcd-1234567890ab \ --from-literal=secretaccesskey=abcdefg_hijklmn_opqrstuvwxy_z0123456789ABCD ``` Additional information about Kubernetes `secrets` functionality can be found in the [Kubernetes documentation](https://kubernetes.io/docs/concepts/configuration/secret/). ### Agent temporary volume For added security, we recommended the `sigsci-agent` container be executed with the root filesystem mounted as read only. However, the agent still needs to write some temporary files such as the socket file for RPC communication and some periodically updated files such as geolocation data. To accomplish this with a read only root filesystem, there needs to be a writeable volume mounted. This writeable volume can also be shared to expose the RPC socket file to other containers in the same pod. The recommended way of creating a writeable volume is to use the builtin `emptyDir` volume type. This is typically configured in the `volumes` section of a deployment, as shown in the following example: ```yaml volumes: - name: sigsci-tmp emptyDir: {} ``` Containers will then mount this volume at `/sigsci/tmp`: ```yaml volumeMounts: - name: sigsci-tmp mountPath: /sigsci/tmp ``` The default in the official agent container image is to have the temporary volume mounted at `/sigsci/tmp`. If this needs to be moved for the agent container, then the following agent configuration options should also be changed from their defaults to match the new mount location: - `rpc-address` defaults to `/sigsci/tmp/sigsci.sock` - `shared-cache-dir` defaults to `/sigsci/tmp/cache` ## Next-Gen WAF agent with a web application and Next-Gen WAF module installed This deployment example configures the example `helloworld` application to use the `sigsci-agent` via RPC and deploys the `sigsci-agent` container as a sidecar to process these RPC requests. To configure Next-Gen WAF with this deployment type you must: - Modify your application to add the appropriate Next-Gen WAF module, configured it to communicate with a `sigsci-agent` via RPC. - Add the sigsci-agent container to the pod, configured in RPC mode. - Add an `emptyDir{}` volume as a place for the `sigsci-agent` to write temporary data and share the RPC address. ### Modifying and configuring the application container The `helloworld` example is a language based module (Golang) that has already been modified to enable communication to the `sigsci-agent` via RPC if configured to do so. This configuration is done via arguments passed to the `helloworld` example application as follows: - Listening address (defaults to `localhost:8000`). - Optional Next-Gen WAF agent RPC address (default is to not use the `sigsci-agent`). Other [language based modules](https://www.fastly.com/documentation/guides/next-gen-waf/setup-and-configuration/module-agent-deployment/about-module-agent-deployment#language-and-framework-specific-module-rasp-options) are similar. [Web server based modules](https://www.fastly.com/documentation/guides/next-gen-waf/setup-and-configuration/module-agent-deployment/about-module-agent-deployment#web-server-module-options) must have the Next-Gen WAF module added to the container. For this `helloworld` application to work with the `sigsci-agent` it must have the `sigsci-agent` address configured as the second program argument and the `sigsci-tmp` volume mounted so that it can write to the socket file: ```yaml ... containers: # Example helloworld app running on port 8000 against sigsci-agent via UDP /sigsci/tmp/sigsci.sock - name: helloworld image: signalsciences/example-helloworld:latest imagePullPolicy: IfNotPresent args: # Address for the app to listen on - localhost:8000 # Address sigsci-agent RPC is listening on - /sigsci/tmp/sigsci.sock ports: - containerPort: 8000 volumeMounts: # Shared mount with sigsci-agent container where the socket is shared via emptyDir volume - name: sigsci-tmp mountPath: /sigsci/tmp ``` ### Adding and configuring the agent container as a sidecar The `sigsci-agent` container will default to RPC mode with a Unix Domain Socket (UDS) file at `/sigsci/tmp/sigsci.sock`. There must be a temp volume mounted at `/sigsci/tmp` to capture this socket file and must be shared with the pod. The web application must be configured to communicate with the `sigsci-agent` via this UDS socket. The deployment YAML must be modified from the example above by adding a second argument to specify the `sigsci-agent` RPC address of `/sigsci/tmp/sigsci.sock`. > **HINT:** It is possible to use a TCP based listener for the `sigsci-agent` RPC, but this is not recommended for performance reasons. If TCP is needed (or UDS is not available, such as in Windows), then the RPC address can be specified as `ip:port` or `host:port` instead of a UDS path. In this case, the volume does not have to be shared with the app, but it does need to be created for the `sigsci-agent` container to have a place to write temporary data such as geodata. #### Adding the `sigsci-agent` container as a sidecar: ```yaml ... containers: # Example helloworld app running on port 8000 against sigsci-agent via UDP /sigsci/tmp/sigsci.sock - name: helloworld image: signalsciences/example-helloworld:latest imagePullPolicy: IfNotPresent args: # Address for the app to listen on - localhost:8000 # Address sigsci-agent RPC is listening on - /sigsci/tmp/sigsci.sock ports: - containerPort: 8000 volumeMounts: # Shared mount with sigsci-agent container where the socket is shared via emptyDir volume - name: sigsci-tmp mountPath: /sigsci/tmp # Next-Gen WAF agent running in default RPC mode - name: sigsci-agent image: signalsciences/sigsci-agent:latest imagePullPolicy: Always env: - name: SIGSCI_ACCESSKEYID valueFrom: secretKeyRef: # This secret needs added (see docs on sigsci secrets) name: sigsci.my-site-name-here key: accesskeyid - name: SIGSCI_SECRETACCESSKEY valueFrom: secretKeyRef: # This secret needs added (see docs on sigsci secrets) name: sigsci.my-site-name-here key: secretaccesskey # If required (default is /sigsci/tmp/sigsci.sock for the container) #- name: SIGSCI_RPC_ADDRESS # value: /path/to/socket for UDS OR host:port if TCP securityContext: # The sigsci-agent container should run with its root filesystem read only readOnlyRootFilesystem: true volumeMounts: # Default volume mount location for sigsci-agent writeable data # NOTE: Also change `SIGSCI_SHARED_CACHE_DIR` (default `/sigsci/tmp/cache`) # if mountPath is changed, but best not to change. - name: sigsci-tmp mountPath: /sigsci/tmp ``` > **NOTE:** The above `sigsci-agent` configuration assumes that `sigsci` secrets were added to the system section above. #### Adding the agent temp volume definition to the deployment Finally, the agent temp volume needs to be defined for use by the other containers in the pod. This uses the builtin `emptyDir: {}` volume type. ```yaml ... volumes: # Define a volume where sigsci-agent will write temp data and share the socket file, # which is required with the root filesystem is mounted read only - name: sigsci-tmp emptyDir: {} ``` ## Related content - [Kubernetes installation overview](https://www.fastly.com/documentation/guides/next-gen-waf/setup-and-configuration/kubernetes/kubernetes-intro) - [Kubernetes agent scaling](https://www.fastly.com/documentation/guides/next-gen-waf/setup-and-configuration/kubernetes/kubernetes-agent-scaling)