[Service Mesh] Linkerd 2 Demo Case 介紹

 

Linkerd2 Demo Case 介紹

步驟

###Step 1: Install the CLI###
curl -sL run.linkerd.io/install | sh
export PATH=$PATH:/home/liudanny/.linkerd2/bin

###Step 2: Validate your Kubernetes cluster###
linkerd check --pre

###Step 3: Install the control plane onto your cluster###
linkerd install | kubectl apply -f -
linkerd check
linkerd viz install | kubectl apply -f - # on-cluster metrics stack

###Step 4: Explore Linkerd
linkerd viz dashboard &
linkerd -n **linkerd-viz** viz top deploy/web

###Step 5: Install the demo app###
curl -sL <https://run.linkerd.io/emojivoto.yml> \\
  | kubectl apply -f -
#add Linkerd to emojivoto by running
kubectl get -n emojivoto deploy -o yaml \\
  | linkerd inject - \\
  | kubectl apply -f -
linkerd -n emojivoto check --proxy

###Step 6: Watch it run###
linkerd -n emojivoto viz stat deploy
linkerd -n emojivoto viz top deploy
linkerd -n emojivoto viz tap deploy/web

###Step 7 (uninstall)###
kubectl get -n emojivoto deploy -o yaml \\
  | linkerd uninject - \\
  | kubectl apply -f -
curl -sL <https://run.linkerd.io/emojivoto.yml> \\
  | kubectl delete -f -
linkerd viz uninstall | kubectl delete -f -
linkerd uninstall | kubectl delete -f -

實驗

###測試自己的namespace
$kubectl get -n default deploy -o yaml \\
  | linkerd inject - \\
  | kubectl apply -f -

$kubectl exec tiefighter -- curl -s -XPOST deathstar.default.svc.cluster.local/v1/request-landing

#uninject 
$kubectl get -n default deploy -o yaml \\
  | linkerd uninject - \\
  | kubectl apply -f -

### not work!!!
$kubectl get -n default pod -o yaml \\
  | linkerd inject - \\
  | kubectl apply -f -
#uninject 
$kubectl get -n default pod -o yaml \\
  | linkerd uninject - \\
  | kubectl apply -f -

心得

View the Linkerd dashboard and see all the services in the demo app. Since the demo app comes with a load generator, we can see live traffic metrics HTTP/2（gRPC）和HTTP/1（web frontend） by running: linkerd -n emojivoto viz stat deploy

This will show the “golden” metrics for each deployment:

• Success rates
• Request rates
• Latency distribution percentiles

Inject function is very convenient for users.

There is no service perspective for metrics, but deployment/Pods/... can kind of cover this.

相關執行結果參考

$ k get all -n emojivoto
NAME                            READY   STATUS    RESTARTS   AGE
pod/emoji-696d9d8f95-p2xv5      2/2     Running   0          64m
pod/vote-bot-6d7677bb68-tmbfq   2/2     Running   0          64m
pod/voting-ff4c54b8d-whssp      2/2     Running   0          64m
pod/web-5f86686c4d-l8lcb        2/2     Running   0          64m

NAME                 TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)             AGE
service/emoji-svc    ClusterIP   10.106.16.101    <none>        8080/TCP,8801/TCP   105m
service/voting-svc   ClusterIP   10.109.94.225    <none>        8080/TCP,8801/TCP   105m
service/web-svc      ClusterIP   10.100.247.154   <none>        80/TCP              105m

NAME                       READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/emoji      1/1     1            1           105m
deployment.apps/vote-bot   1/1     1            1           105m
deployment.apps/voting     1/1     1            1           105m
deployment.apps/web        1/1     1            1           105m

NAME                                  DESIRED   CURRENT   READY   AGE
replicaset.apps/emoji-66ccdb4d86      0         0         0       105m
replicaset.apps/emoji-696d9d8f95      1         1         1       64m
replicaset.apps/vote-bot-69754c864f   0         0         0       105m
replicaset.apps/vote-bot-6d7677bb68   1         1         1       64m
replicaset.apps/voting-f999bd4d7      0         0         0       105m
replicaset.apps/voting-ff4c54b8d      1         1         1       64m
replicaset.apps/web-5f86686c4d        1         1         1       64m
replicaset.apps/web-79469b946f        0         0         0       105m

$ linkerd -n emojivoto viz stat deploy
NAME       MESHED   SUCCESS      RPS   LATENCY_P50   LATENCY_P95   LATENCY_P99   TCP_CONN
emoji         1/1   100.00%   2.3rps           1ms           1ms           1ms          3
vote-bot      1/1   100.00%   0.3rps           1ms           1ms           1ms          1
voting        1/1    87.01%   1.3rps           1ms           1ms           2ms          3
web           1/1    91.91%   2.3rps           2ms          16ms          19ms          3

$ linkerd -n emojivoto viz top deploy
(press q to quit)
(press a/LeftArrowKey to scroll left, d/RightArrowKey to scroll right)

Source                     Destination             Method      Path                                                    Count    Best   Worst    Last  Success Rate
web-5f86686c4d-l8lcb       emoji-696d9d8f95-p2xv5  POST        /emojivoto.v1.EmojiService/ListAll                         42   562µs     5ms   937µs       100.00%
vote-bot-6d7677bb68-tmbfq  web-5f86686c4d-l8lcb    GET         /api/list                                                  42     3ms    13ms     9ms       100.00%
web-5f86686c4d-l8lcb       emoji-696d9d8f95-p2xv5  POST        /emojivoto.v1.EmojiService/FindByShortcode                 42   553µs    13ms     2ms       100.00%
vote-bot-6d7677bb68-tmbfq  web-5f86686c4d-l8lcb    GET         /api/vote                                                  41     5ms    21ms     6ms        87.80%
web-5f86686c4d-l8lcb       voting-ff4c54b8d-whssp  POST        /emojivoto.v1.VotingService/VoteDoughnut                    6   926µs     3ms     2ms         0.00%
web-5f86686c4d-l8lcb       voting-ff4c54b8d-whssp  POST        /emojivoto.v1.VotingService/VoteMrsClaus                    4     1ms     2ms     2ms       100.00%
web-5f86686c4d-l8lcb       voting-ff4c54b8d-whssp  POST        /emojivoto.v1.VotingService/VoteRocket                      2     2ms     3ms     3ms       100.00%
web-5f86686c4d-l8lcb       voting-ff4c54b8d-whssp  POST        /emojivoto.v1.VotingService/VotePointUp2                    2     2ms     3ms     3ms       100.00%
web-5f86686c4d-l8lcb       voting-ff4c54b8d-whssp  POST        /emojivoto.v1.VotingService/VoteCrossedSwords               2     2ms     3ms     3ms       100.00%
web-5f86686c4d-l8lcb       voting-ff4c54b8d-whssp  POST        /emojivoto.v1.VotingService/VoteWorldMap                    2   739µs     2ms     2ms       100.00%
web-5f86686c4d-l8lcb       voting-ff4c54b8d-whssp  POST        /emojivoto.v1.VotingService/VoteDog                         2     2ms     2ms     2ms       100.00%
web-5f86686c4d-l8lcb       voting-ff4c54b8d-whssp  POST        /emojivoto.v1.VotingService/VoteOkWoman                     2   951µs     2ms     2ms       100.00%
web-5f86686c4d-l8lcb       voting-ff4c54b8d-whssp  POST        /emojivoto.v1.VotingService/VoteNerdFace                    2     2ms     9ms     9ms       100.00%
web-5f86686c4d-l8lcb       voting-ff4c54b8d-whssp  POST        /emojivoto.v1.VotingService/VoteConstructionWorkerMan       2     1ms     3ms     3ms       100.00%
web-5f86686c4d-l8lcb       voting-ff4c54b8d-whssp  POST        /emojivoto.v1.VotingService/VoteCheckeredFlag               2   863µs     3ms   863µs       100.00%
web-5f86686c4d-l8lcb       voting-ff4c54b8d-whssp  POST        /emojivoto.v1.VotingService/Vote100                         2   894µs     2ms   894µs       100.00%
web-5f86686c4d-l8lcb       voting-ff4c54b8d-whssp  POST        /emojivoto.v1.VotingService/VotePizza                       2     1ms     3ms     3ms       100.00%
web-5f86686c4d-l8lcb       voting-ff4c54b8d-whssp  POST        /emojivoto.v1.VotingService/VoteJackOLantern                2   884µs     3ms     3ms       100.00%
web-5f86686c4d-l8lcb       voting-ff4c54b8d-whssp  POST        /emojivoto.v1.VotingService/VoteManDancing                  2   761µs     1ms     1ms       100.00%
web-5f86686c4d-l8lcb       voting-ff4c54b8d-whssp  POST        /emojivoto.v1.VotingService/VoteBeachUmbrella               2     1ms     2ms     1ms       100.00%
web-5f86686c4d-l8lcb       voting-ff4c54b8d-whssp  POST        /emojivoto.v1.VotingService/VoteNoGoodWoman                 2     1ms     2ms     2ms       100.00%
web-5f86686c4d-l8lcb       voting-ff4c54b8d-whssp  POST        /emojivoto.v1.VotingService/VoteGuardsman                   2   968µs     2ms     2ms       100.00%

**$ linkerd -n emojivoto viz tap deploy/web**
req id=11:0 proxy=in  src=10.244.109.92:46446 dst=10.244.109.115:8080 tls=true :method=GET :authority=web-svc.emojivoto:80 :path=/api/list
req id=11:1 proxy=out src=10.244.109.115:55194 dst=10.244.109.109:8080 tls=true :method=POST :authority=emoji-svc.emojivoto:8080 :path=/emojivoto.v1.EmojiService/ListAll
rsp id=11:1 proxy=out src=10.244.109.115:55194 dst=10.244.109.109:8080 tls=true :status=200 latency=1792µs
end id=11:1 proxy=out src=10.244.109.115:55194 dst=10.244.109.109:8080 tls=true grpc-status=OK duration=193µs response-length=2140B
rsp id=11:0 proxy=in  src=10.244.109.92:46446 dst=10.244.109.115:8080 tls=true :status=200 latency=4294µs
end id=11:0 proxy=in  src=10.244.109.92:46446 dst=10.244.109.115:8080 tls=true duration=358µs response-length=4513B
req id=11:2 proxy=in  src=10.244.109.92:46446 dst=10.244.109.115:8080 tls=true :method=GET :authority=web-svc.emojivoto:80 :path=/api/vote
req id=11:3 proxy=out src=10.244.109.115:55194 dst=10.244.109.109:8080 tls=true :method=POST :authority=emoji-svc.emojivoto:8080 :path=/emojivoto.v1.EmojiService/FindByShortcode
rsp id=11:3 proxy=out src=10.244.109.115:55194 dst=10.244.109.109:8080 tls=true :status=200 latency=1657µs
end id=11:3 proxy=out src=10.244.109.115:55194 dst=10.244.109.109:8080 tls=true grpc-status=OK duration=175µs response-length=25B
req id=11:4 proxy=out src=10.244.109.115:33470 dst=10.244.109.84:8080 tls=true :method=POST :authority=voting-svc.emojivoto:8080 :path=/emojivoto.v1.VotingService/VoteDoughnut
rsp id=11:4 proxy=out src=10.244.109.115:33470 dst=10.244.109.84:8080 tls=true :status=200 latency=2217µs
end id=11:4 proxy=out src=10.244.109.115:33470 dst=10.244.109.84:8080 tls=true grpc-status=Unknown duration=161µs response-length=0B
rsp id=11:2 proxy=in  src=10.244.109.92:46446 dst=10.244.109.115:8080 tls=true :status=500 latency=8272µs
end id=11:2 proxy=in  src=10.244.109.92:46446 dst=10.244.109.115:8080 tls=true duration=171µs response-length=51B
req id=11:5 proxy=in  src=10.244.109.92:46446 dst=10.244.109.115:8080 tls=true :method=GET :authority=web-svc.emojivoto:80 :path=/api/list
req id=11:6 proxy=out src=10.244.109.115:55194 dst=10.244.109.109:8080 tls=true :method=POST :authority=emoji-svc.emojivoto:8080 :path=/emojivoto.v1.EmojiService/ListAll
rsp id=11:6 proxy=out src=10.244.109.115:55194 dst=10.244.109.109:8080 tls=true :status=200 latency=1483µs
end id=11:6 proxy=out src=10.244.109.115:55194 dst=10.244.109.109:8080 tls=true grpc-status=OK duration=145µs response-length=2140B
rsp id=11:5 proxy=in  src=10.244.109.92:46446 dst=10.244.109.115:8080 tls=true :status=200 latency=5621µs
end id=11:5 proxy=in  src=10.244.109.92:46446 dst=10.244.109.115:8080 tls=true duration=336µs response-length=4513B
req id=11:7 proxy=in  src=10.244.109.92:46446 dst=10.244.109.115:8080 tls=true :method=GET :authority=web-svc.emojivoto:80 :path=/api/vote
req id=11:8 proxy=out src=10.244.109.115:55194 dst=10.244.109.109:8080 tls=true :method=POST :authority=emoji-svc.emojivoto:8080 :path=/emojivoto.v1.EmojiService/FindByShortcode
rsp id=11:8 proxy=out src=10.244.109.115:55194 dst=10.244.109.109:8080 tls=true :status=200 latency=1477µs
end id=11:8 proxy=out src=10.244.109.115:55194 dst=10.244.109.109:8080 tls=true grpc-status=OK duration=206µs response-length=28B
req id=11:9 proxy=out src=10.244.109.115:33470 dst=10.244.109.84:8080 tls=true :method=POST :authority=voting-svc.emojivoto:8080 :path=/emojivoto.v1.VotingService/VoteManDancing
rsp id=11:9 proxy=out src=10.244.109.115:33470 dst=10.244.109.84:8080 tls=true :status=200 latency=1560µs
end id=11:9 proxy=out src=10.244.109.115:33470 dst=10.244.109.84:8080 tls=true grpc-status=OK duration=144µs response-length=5B
rsp id=11:7 proxy=in  src=10.244.109.92:46446 dst=10.244.109.115:8080 tls=true :status=200 latency=7140µs
end id=11:7 proxy=in  src=10.244.109.92:46446 dst=10.244.109.115:8080 tls=true duration=96µs response-length=0B
req id=11:10 proxy=in  src=10.244.109.92:46446 dst=10.244.109.115:8080 tls=true :method=GET :authority=web-svc.emojivoto:80 :path=/api/list
req id=11:11 proxy=out src=10.244.109.115:55194 dst=10.244.109.109:8080 tls=true :method=POST :authority=emoji-svc.emojivoto:8080 :path=/emojivoto.v1.EmojiService/ListAll
rsp id=11:11 proxy=out src=10.244.109.115:55194 dst=10.244.109.109:8080 tls=true :status=200 latency=1855µs
end id=11:11 proxy=out src=10.244.109.115:55194 dst=10.244.109.109:8080 tls=true grpc-status=OK duration=375µs response-length=2140B
rsp id=11:10 proxy=in  src=10.244.109.92:46446 dst=10.244.109.115:8080 tls=true :status=200 latency=3786µs
end id=11:10 proxy=in  src=10.244.109.92:46446 dst=10.244.109.115:8080 tls=true duration=339µs response-length=4513B
req id=11:12 proxy=in  src=10.244.109.92:46446 dst=10.244.109.115:8080 tls=true :method=GET :authority=web-svc.emojivoto:80 :path=/api/vote

[Service Mesh] Linkerd2 Features 重點整理

 整理官方文件 https://linkerd.io/2.10/features/ 如下:

HTTP, HTTP/2, and gRPC Proxying

Linkerd can proxy all TCP connections, and will automatically enable advanced features (including metrics, load balancing, retries, and more) for HTTP, HTTP/2, and gRPC connections.

TCP Proxying and Protocol Detection

Linkerd is capable of proxying all TCP traffic, including TLS connections, WebSockets, and HTTP tunneling.

In most cases, Linkerd can do this without configuration. To do this, Linkerd performs protocol detection to determine whether traffic is HTTP or HTTP/2 (including gRPC). If Linkerd detects that a connection is HTTP or HTTP/2, Linkerd will automatically provide HTTP-level metrics and routing.

If Linkerd cannot determine that a connection is using HTTP or HTTP/2**, Linkerd will proxy the connection as a plain TCP connection, applying mTLS and providing byte-level metrics** as usual.

Note Client-initiated HTTPS will be treated as TCP, not as HTTP, as Linkerd will not be able to observe the HTTP transactions on the connection.

Configuring protocol detection

( We ITRI currently get TCP info from Layer 4 Network Stack in Kernel )

In some cases, Linkerd’s protocol detection cannot function because it is not provided with enough client data. This can result in a 10-second delay in creating the connection as the protocol detection code waits for more data. This situation is often encountered when using “server-speaks-first” protocols, or protocols where the server sends data before the client does, and can be avoided by supplying Linkerd with some additional configuration.

There are two basic mechanisms for configuring protocol detection: opaque ports and skip ports. Marking a port as opaque instructs Linkerd to proxy the connection as a TCP stream and not to attempt protocol detection. Marking a port as skip bypasses the proxy entirely.

By default, Linkerd automatically marks some ports as opaque, including the default ports for SMTP, MySQL, PostgresQL, and Memcache. Services that speak those protocols, use the default ports, and are inside the cluster do not need further configuration.

The following table summarizes some common server-speaks-first protocols and the configuration necessary to handle them. The “on-cluster config” column refers to the configuration when the destination is on the same cluster; the “off-cluster config” to when the destination is external to the cluster.

some common server-speaks-first protocols

• No configuration is required if the standard port is used. If a non-standard port is used, you must mark the port as opaque.

Retries and Timeouts

Automatic retries are one the most powerful and useful mechanisms a service mesh has for gracefully handling partial or transient application failures.

Timeouts work hand in hand with retries. Once requests are retried a certain number of times, it becomes important to limit the total amount of time a client waits before giving up entirely. Imagine a number of retries forcing a client to wait for 10 seconds.

Automatic mTLS

By default, Linkerd automatically enables mutual Transport Layer Security (mTLS) for most TCP traffic between meshed pods, by establishing and authenticating secure, private TLS connections between Linkerd proxies. This means that Linkerd can add authenticated, encrypted communication to your application with very little work on your part.

Telemetry and Monitoring

One of Linkerd’s most powerful features is its extensive set of tooling around observability—the measuring and reporting of observed behavior in meshed applications

To gain access to Linkerd’s observability features you only need to install the Viz extension:

linkerd viz install | kubectl apply -f -

Linkerd’s telemetry and monitoring features function automatically, without requiring any work on the part of the developer. These features include:

• Recording of top-line (“golden”) metrics (request volume, success rate, and latency distributions) for HTTP, HTTP/2, and gRPC traffic.
• Recording of TCP-level metrics (bytes in/out, etc) for other TCP traffic. (We ITRI record TCP and UDP Tx/Rx bytes both)
• Reporting metrics per service, per caller/callee pair, or per route/path (with Service Profiles).
• Generating topology graphs that display the runtime relationship between services.
• Live, on-demand request sampling.

This data can be consumed in several ways:

• Through the Linkerd CLI, e.g. with linkerd viz stat and linkerd viz routes.
• Through the Linkerd dashboard, and pre-built Grafana dashboards.
• Directly from Linkerd’s built-in Prometheus instance

Golden metrics

Success Rate

This is the percentage of successful requests during a time window (1 minute by default).

In the output of the command linkerd viz routes -o wide, this metric is split into EFFECTIVE_SUCCESS and ACTUAL_SUCCESS. For routes configured with retries, the former calculates the percentage of success after retries (as perceived by the client-side), and the latter before retries (which can expose potential problems with the service).

Traffic (Requests Per Second)

This gives an overview of how much demand is placed on the service/route. As with success rates, linkerd viz routes --o wide splits this metric into EFFECTIVE_RPS and ACTUAL_RPS, corresponding to rates after and before retries respectively.

Latencies ( We ITRI's latency is defined as time to client → server → client . We also have service's response time)

Times taken to service requests per service/route are split into 50th, 95th and 99th percentiles. Lower percentiles give you an overview of the average performance of the system, while tail percentiles help catch outlier behavior.

Load Balancing

For HTTP, HTTP/2, and gRPC connections, Linkerd automatically load balances requests across all destination endpoints without any configuration required. (For TCP connections, Linkerd will balance connections.)

Linkerd uses an algorithm called EWMA, or exponentially weighted moving average, to automatically send requests to the fastest endpoints. This load balancing can improve end-to-end latencies.

Service discovery

For destinations that are not in Kubernetes, Linkerd will balance across endpoints provided by DNS.

For destinations that are in Kubernetes, Linkerd will look up the IP address in the Kubernetes API. If the IP address corresponds to a Service, Linkerd will load balance across the endpoints of that Service and apply any policy from that Service’s Service Profile. On the other hand, if the IP address corresponds to a Pod, Linkerd will not perform any load balancing or apply any Service Profiles.

Load balancing gRPC

Linkerd’s load balancing is particularly useful for gRPC (or HTTP/2) services in Kubernetes, for which Kubernetes’s default load balancing is not effective.

Automatic Proxy Injection

Linkerd automatically adds the data plane proxy to pods when the linkerd.io/inject: enabled annotation is present on a namespace or any workloads, such as deployments or pods. This is known as “proxy injection”. ( Here a lot of details in Adding Your Services to Linkerd)

Details

Proxy injection is implemented as a Kubernetes admission webhook. This means that the proxies are added to pods within the Kubernetes cluster itself, regardless of whether the pods are created by kubectl, a CI/CD system, or any other system.

For each pod, two containers are injected:

1. linkerd-init, a Kubernetes Init Container that configures iptables to automatically forward all incoming and outgoing TCP traffic through the proxy. (Note that this container is not present if the Linkerd CNI Plugin has been enabled.)
2. linkerd-proxy, the Linkerd data plane proxy itself.

Note that simply adding the annotation to a resource with pre-existing pods will not automatically inject those pods. You will need to update the pods (e.g. with kubectl rollout restart etc.) for them to be injected. This is because Kubernetes does not call the webhook until it needs to update the underlying resources.

CNI Plugin

Linkerd installs can be configured to run a CNI plugin that rewrites each pod’s iptables rules automatically. Rewriting iptables is required for routing network traffic through the pod’s linkerd-proxy container. When the CNI plugin is enabled, individual pods no longer need to include an init container that requires the NET_ADMIN capability to perform rewriting. This can be useful in clusters where that capability is restricted by cluster administrators.

Distributed Tracing

(We ITRI don't require code changes. We provide the downstream of related trajectories )

Linkerd can be configured to emit trace spans from the proxies, allowing you to see exactly what time requests and responses spend inside.

Unlike most of the features of Linkerd, distributed tracing requires both code changes and configuration. (You can read up on Distributed tracing in the service mesh: four myths for why this is.)

Furthermore, Linkerd provides many of the features that are often associated with distributed tracing, without requiring configuration or application changes, including:

• Live service topology and dependency graphs
• Aggregated service health, latencies, and request volumes
• Aggregated path / route health, latencies, and request volumes

For example, Linkerd can display a live topology of all incoming and outgoing dependencies for a service, without requiring distributed tracing or any other such application modification:

The Linkerd dashboard showing an automatically generated topology graph