108 lines
5.8 KiB
Markdown
108 lines
5.8 KiB
Markdown
# Observe Service Mesh through ALS
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[Envoy Access Log Service (ALS)](https://www.envoyproxy.io/docs/envoy/latest/api-v2/service/accesslog/v2/als.proto) provides
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full logs about RPC routed, including HTTP and TCP.
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## Background
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The solution was initialized and firstly implemented by [Sheng Wu](https://github.com/wu-sheng), [Hongtao Gao](https://github.com/hanahmily), [Lizan Zhou](https://github.com/lizan),
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and [Dhi Aurrahman](https://github.com/dio) at 17 May. 2019, and was presented on [KubeCon China 2019](https://kccncosschn19eng.sched.com/event/NroB/observability-in-service-mesh-powered-by-envoy-and-apache-skywalking-sheng-wu-lizan-zhou-tetrate).
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Here is the recorded [video](https://www.youtube.com/watch?v=tERm39ju9ew).
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SkyWalking is the first open source project introducing this ALS based solution to the world. This provides a new way with very low payload to service mesh, but the same observability.
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## Enable ALS and SkyWalking Receiver
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You need the following steps to set up ALS.
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- Enable [`envoyAccessLogService` in ProxyConfig](https://istio.io/docs/reference/config/istio.mesh.v1alpha1/#ProxyConfig) and set the ALS address to where SkyWalking OAP listens.
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On Istio version 1.6.0+, if Istio is installed with [`demo` profile](https://istio.io/latest/docs/setup/additional-setup/config-profiles/), you can enable ALS with command:
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```shell
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istioctl manifest apply \
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--set profile=demo \
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--set meshConfig.enableEnvoyAccessLogService=true \
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--set meshConfig.defaultConfig.envoyAccessLogService.address=<skywalking-oap.skywalking.svc:11800>
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```
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Note: Replace `<skywalking-oap.skywalking.svc:11800>` with the real address where SkyWalking OAP is deployed.
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- Activate SkyWalking [Envoy Receiver](../backend/backend-receivers.md). This is activated by default.
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- Choose an ALS analyzer. There are two available analyzers, `k8s-mesh` and `mx-mesh`.
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Set the system environment variable **SW_ENVOY_METRIC_ALS_HTTP_ANALYSIS** such as `SW_ENVOY_METRIC_ALS_HTTP_ANALYSIS=k8s-mesh`
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or in the `application.yaml` to activate the analyzer. For more about the analyzers, see [SkyWalking ALS Analyzers](#skywalking-als-analyzers)
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```yaml
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envoy-metric:
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selector: ${SW_ENVOY_METRIC:default}
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default:
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acceptMetricsService: ${SW_ENVOY_METRIC_SERVICE:true}
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alsHTTPAnalysis: ${SW_ENVOY_METRIC_ALS_HTTP_ANALYSIS:""} # Setting the system env variable would override this.
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```
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To use multiple analyzers as a fallback，please use `,` to concatenate.
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## Example
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Here's an example to install Istio and deploy SkyWalking by Helm chart.
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```shell
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istioctl install \
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--set profile=demo \
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--set meshConfig.enableEnvoyAccessLogService=true \
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--set meshConfig.defaultConfig.envoyAccessLogService.address=skywalking-oap.istio-system:11800
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git clone https://github.com/apache/skywalking-kubernetes.git
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cd skywalking-kubernetes/chart
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helm repo add elastic https://helm.elastic.co
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helm dep up skywalking
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helm install 8.1.0 skywalking -n istio-system \
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--set oap.env.SW_ENVOY_METRIC_ALS_HTTP_ANALYSIS=k8s-mesh \
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--set fullnameOverride=skywalking \
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--set oap.envoy.als.enabled=true
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```
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You can use `kubectl -n istio-system logs -l app=skywalking | grep "K8sALSServiceMeshHTTPAnalysis"` to ensure OAP ALS `k8s-mesh` analyzer has been activated.
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## SkyWalking ALS Analyzers
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There are several available analyzers, `k8s-mesh`, `mx-mesh` and `persistence`, you can specify one or more
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analyzers to analyze the access logs. When multiple analyzers are specified, it acts as a fast-success mechanism:
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SkyWalking loops over the analyzers and use it to analyze the logs, once there is an analyzer that is able to produce a
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result, it stops the loop.
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### `k8s-mesh`
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`k8s-mesh` uses the metadata from Kubernetes cluster, hence in this analyzer OAP needs access roles to `Pod`, `Service`, and `Endpoints`.
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The [blog](https://skywalking.apache.org/blog/2020-12-03-obs-service-mesh-with-sw-and-als/) illustrates the detail of how it works, and a step-by-step tutorial to apply it into the `bookinfo` application.
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### `mx-mesh`
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`mx-mesh` uses the Envoy metadata exchange mechanism to get the service name, etc.,
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this analyzer requires Istio to enable the metadata exchange plugin (you can enable it by `--set values.telemetry.v2.enabled=true`,
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or if you're using Istio 1.7+ and installing it with profile `demo`/`preview`, it should be enabled then).
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The [blog](https://skywalking.apache.org/blog/obs-service-mesh-vm-with-sw-and-als/) illustrates the detail of how it works, and a step-by-step tutorial to apply it into the [Online Boutique](https://github.com/GoogleCloudPlatform/microservices-demo) system.
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### `persistence`
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`persistence` analyzer adapts the Envoy access log format to
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SkyWalking's [native log format](https://github.com/apache/skywalking-data-collect-protocol/blob/master/logging/Logging.proto)
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, and forwards the formatted logs to [LAL](../../concepts-and-designs/lal.md), where you can configure persistent
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conditions, such as `sampler`, only persist error logs, etc. SkyWalking provides a default configuration
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file [`envoy-als.yaml`](../../../../oap-server/server-bootstrap/src/main/resources/lal/envoy-als.yaml) that you can
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adjust as per your needs. Please make sure to activate this rule via adding the rule name `envoy-als`
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into config item `log-analyzer/default/lalFiles` (or environment variable `SW_LOG_LAL_FILES`,
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e.g. `SW_LOG_LAL_FILES=envoy-als`).
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**Attention**: because `persistence` analyzer also needs a mechanism to map the logs into responding services, hence,
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you need to configure at least one of `k8s-mesh` or `mx-mesh` as its antecedent so that `persistence` analyzer knows
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which service the logs belong to. For example, you should set `envoy-metric/default/alsHTTPAnalysis` (or environment
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variable `SW_ENVOY_METRIC_ALS_HTTP_ANALYSIS`) to something like `k8s-mesh,persistence`, `mx-mesh,persistence`
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or `mx-mesh,k8s-mesh,persistence`.
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