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feat: add support for traffic router plugins (#2573)
* feat: add support for traffic router plugins Signed-off-by: zachaller <[email protected]> * finish up refactor Signed-off-by: zachaller <[email protected]> * codegen Signed-off-by: zachaller <[email protected]> * update docs Signed-off-by: zachaller <[email protected]> * rename config field Signed-off-by: zachaller <[email protected]> * refactor tests Signed-off-by: zachaller <[email protected]> * add godocs Signed-off-by: zachaller <[email protected]> * add docs on creating plugins Signed-off-by: zachaller <[email protected]> * rename config fields Signed-off-by: zachaller <[email protected]> * Change New function to Init for tr Signed-off-by: zachaller <[email protected]> * Change New function to Init for metrics Signed-off-by: zachaller <[email protected]> * docs update Signed-off-by: zachaller <[email protected]> * docs update Signed-off-by: zachaller <[email protected]> * codegen Signed-off-by: zachaller <[email protected]> * change repo name Signed-off-by: zachaller <[email protected]> * small docs changes Signed-off-by: zachaller <[email protected]> * fix bad merge comments Signed-off-by: zachaller <[email protected]> * remove metric passing from metrics plugin on Init method Signed-off-by: zachaller <[email protected]> * fix mutex Signed-off-by: zachaller <[email protected]> * wrap errors Signed-off-by: zachaller <[email protected]> * rename Signed-off-by: zachaller <[email protected]> * docs change Signed-off-by: zachaller <[email protected]> * codegen Signed-off-by: zachaller <[email protected]> * some updates to docs Signed-off-by: zachaller <[email protected]> * change plugin to plugins for tr Signed-off-by: zachaller <[email protected]> * change plugin to plugins for tr Signed-off-by: zachaller <[email protected]> * refactor naming for metric plugins Signed-off-by: zachaller <[email protected]> * lint Signed-off-by: zachaller <[email protected]> * change handshake Signed-off-by: zachaller <[email protected]> * more renames Signed-off-by: zachaller <[email protected]> * change handshake Signed-off-by: zachaller <[email protected]> * add err context Signed-off-by: zachaller <[email protected]> * lint Signed-off-by: zachaller <[email protected]> * small docs change Signed-off-by: zachaller <[email protected]> * docs update from pr review Signed-off-by: zachaller <[email protected]> * updates from review Signed-off-by: zachaller <[email protected]> * change config map format Signed-off-by: zachaller <[email protected]> * update docs Signed-off-by: zachaller <[email protected]> * add context to error Signed-off-by: zachaller <[email protected]> * add context to error Signed-off-by: zachaller <[email protected]> * add context to errors ans well as wrap the *bool returned by verifiy weight Signed-off-by: zachaller <[email protected]> * update docs for new interface type Signed-off-by: zachaller <[email protected]> * change error wraping for init Signed-off-by: zachaller <[email protected]> --------- Signed-off-by: zachaller <[email protected]>
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| # Traffic Router Plugins | ||
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| !!! important Available since v1.5 - Status: Alpha | ||
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| Argo Rollouts supports getting analysis metrics via 3rd party plugin system. This allows users to extend the capabilities of Rollouts | ||
| to support metric providers that are not natively supported. Rollout's uses a plugin library called | ||
| [go-plugin](https://github.com/hashicorp/go-plugin) to do this. You can find a sample plugin | ||
| here: [rollouts-sample_nginx-trafficrouter-plugin](https://github.com/argoproj-labs/rollouts-sample_nginx-trafficrouter-plugin) | ||
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| ## Using a Traffic Router Plugin | ||
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| There are two methods of installing and using an argo rollouts plugin. The first method is to mount up the plugin executable | ||
| into the rollouts controller container. The second method is to use a HTTP(S) server to host the plugin executable. | ||
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| ### Mounting the plugin executable into the rollouts controller container | ||
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| There are a few ways to mount the plugin executable into the rollouts controller container. Some of these will depend on your | ||
| particular infrastructure. Here are a few methods: | ||
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| * Using an init container to download the plugin executable | ||
| * Using a Kubernetes volume mount with a shared volume such as NFS, EBS, etc. | ||
| * Building the plugin into the rollouts controller container | ||
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| Then you can use the configmap to point to the plugin executable file location. Example: | ||
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| ```yaml | ||
| apiVersion: v1 | ||
| kind: ConfigMap | ||
| metadata: | ||
| name: argo-rollouts-config | ||
| data: | ||
| trafficRouterPlugins: |- | ||
| - name: "argoproj-labs/sample-nginx" # name of the plugin, it must match the name required by the plugin so it can find it's configuration | ||
| location: "file://./my-custom-plugin" # supports http(s):// urls and file:// | ||
| ``` | ||
| ### Using a HTTP(S) server to host the plugin executable | ||
| Argo Rollouts supports downloading the plugin executable from a HTTP(S) server. To use this method, you will need to | ||
| configure the controller via the `argo-rollouts-config` configmap and set `pluginLocation` to a http(s) url. Example: | ||
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| ```yaml | ||
| apiVersion: v1 | ||
| kind: ConfigMap | ||
| metadata: | ||
| name: argo-rollouts-config | ||
| data: | ||
| trafficRouterPlugins: |- | ||
| - name: "argoproj-labs/sample-nginx" # name of the plugin, it must match the name required by the plugin so it can find it's configuration | ||
| location: "https://github.com/argoproj-labs/rollouts-sample_nginx-trafficrouter-plugin/releases/download/v0.0.1/metric-plugin-linux-amd64" # supports http(s):// urls and file:// | ||
| sha256: "08f588b1c799a37bbe8d0fc74cc1b1492dd70b2c" #optional sha256 checksum of the plugin executable | ||
| ``` | ||
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| ## Some words of caution | ||
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| Depending on which method you use to install and the plugin, there are some things to be aware of. | ||
| The rollouts controller will not start if it can not download or find the plugin executable. This means that if you are using | ||
| a method of installation that requires a download of the plugin and the server hosting the plugin for some reason is not available and the rollouts | ||
| controllers pod got deleted while the server was down or is coming up for the first time, it will not be able to start until | ||
| the server hosting the plugin is available again. | ||
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| Argo Rollouts will download the plugin at startup only once but if the pod is deleted it will need to download the plugin again on next startup. Running | ||
| Argo Rollouts in HA mode can help a little with this situation because each pod will download the plugin at startup. So if a single pod gets | ||
| deleted during a server outage, the other pods will still be able to take over because there will already be a plugin executable available to it. It is the | ||
| responsibility of the Argo Rollouts administrator to define the plugin installation method considering the risks of each approach. | ||
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| ## List of Available Plugins (alphabetical order) | ||
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| #### Add Your Plugin Here | ||
| * If you have created a plugin, please submit a PR to add it to this list. | ||
| #### [rollouts-sample_nginx-trafficrouter-plugin](https://github.com/argoproj-labs/rollouts-sample_nginx-trafficrouter-plugin) | ||
| * This is just a sample plugin that can be used as a starting point for creating your own plugin. | ||
| It is not meant to be used in production. It is based on the built-in prometheus provider. |
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| # Creating an Argo Rollouts Plugin | ||
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| ## High Level Overview | ||
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| Argo Rollouts plugins depend on hashicorp's [go-plugin](https://github.com/hashicorp/go-plugin) library. This library | ||
| provides a way for a plugin to be compiled as a standalone executable and then loaded by the rollouts controller at runtime. | ||
| This works by having the plugin executable act as a rpc server and the rollouts controller act as a client. The plugin executable | ||
| is started by the rollouts controller and is a long-lived process and that the rollouts controller connects to over a unix socket. | ||
| The communication protocol uses golang built in net/rpc library so plugins have to be written in golang. | ||
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| ## Plugin Repository | ||
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| In order to get plugins listed in the main argo rollouts documentation we ask that the plugin repository be created under | ||
| the [argoproj-labs](https://github.com/argoproj-labs) organization. Please open an issue under argo-rollouts requesting a | ||
| repo which you would be granted admin access on. | ||
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| There is also a standard naming convention for plugin names used for configmap registration, as well as what the plugin | ||
| uses for locating its specific configuration on rollout or analysis resources. The name needs to be in the form of | ||
| `<namespace>/<name>` and both <namespace> and <name> have a regular expression check that matches Github's requirements | ||
| for `username/org` and `repository name`. This requirement is in place to help with allowing multiple creators of the same plugin | ||
| types to exist such as `<org1>/nginx` and `<org2>/nginx`. These names could be based of the repo name such | ||
| as `argoproj-labs/rollouts-sample_prometheus-metric-plugin` but it is not a requirement. | ||
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| There will also be a standard for naming repositories under argoproj-labs in the form of `rollouts-<tool>-<type>-plugin` | ||
| where `<type>` is say `metric`, or `trafficrouter` and `<tool>` is the software the plugin is for say nginx. | ||
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| ## Plugin Name | ||
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| So now that we have an idea on plugin naming and repository standards let's pick a name to use for the rest of this | ||
| documentation and call our plugin `argoproj-labs/nginx`. | ||
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| This name will be used in a few different spots the first is the config map that your plugin users will need to configure. | ||
| It looks like this below. | ||
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| ```yaml | ||
| kind: ConfigMap | ||
| metadata: | ||
| name: argo-rollouts-config | ||
| data: | ||
| metricProviderPlugins: |- | ||
| - name: "argoproj-labs/metrics" | ||
| location: "file:///tmp/argo-rollouts/metric-plugin" | ||
| trafficRouterPlugins: |- | ||
| - name: "argoproj-labs/nginx" | ||
| location: "file:///tmp/argo-rollouts/traffic-plugin" | ||
| ``` | ||
| As you can see there is a field called `name:` under both `metrics` or `trafficrouters` this is the first place where your | ||
| end users will need to configure the name of the plugin. The second location is either in the rollout object or the analysis | ||
| template which you can see the examples below. | ||
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| #### AnalysisTemplate Example | ||
| ```yaml | ||
| apiVersion: argoproj.io/v1alpha1 | ||
| kind: AnalysisTemplate | ||
| metadata: | ||
| name: success-rate | ||
| spec: | ||
| metrics: | ||
| - name: success-rate | ||
| ... | ||
| provider: | ||
| plugin: | ||
| argoproj-labs/metrics: | ||
| address: http://prometheus.local | ||
| ``` | ||
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| #### Traffic Router Example | ||
| ```yaml | ||
| apiVersion: argoproj.io/v1alpha1 | ||
| kind: Rollout | ||
| metadata: | ||
| name: example-plugin-ro | ||
| spec: | ||
| strategy: | ||
| canary: | ||
| canaryService: example-plugin-ro-canary-analysis | ||
| stableService: example-plugin-ro-stable-analysis | ||
| trafficRouting: | ||
| plugins: | ||
| argoproj-labs/nginx: | ||
| stableIngress: canary-demo | ||
| ``` | ||
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| You can see that we use the plugin name under `spec.metrics[].provider.plugin` for analysis template and `spec.strategy.canary.trafficRouting.plugins` | ||
| for traffic routers. You as a plugin author can then put any configuration you need under `argoproj-labs/nginx` and you will be able to | ||
| look up that config in your plugin via the plugin name key. You will also want to document what configuration options your plugin supports. | ||
|
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| ## Plugin Interfaces | ||
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| Argo Rollouts currently supports two plugin systems as a plugin author your end goal is to implement these interfaces as | ||
| a hashicorp go-plugin. The two interfaces are `MetricsPlugin` and `TrafficRouterPlugin` for each of the respective plugins: | ||
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| ```go | ||
| type MetricProviderPlugin interface { | ||
| // InitPlugin initializes the traffic router plugin this gets called once when the plugin is loaded. | ||
| InitPlugin() RpcError | ||
| // Run start a new external system call for a measurement | ||
| // Should be idempotent and do nothing if a call has already been started | ||
| Run(*v1alpha1.AnalysisRun, v1alpha1.Metric) v1alpha1.Measurement | ||
| // Resume Checks if the external system call is finished and returns the current measurement | ||
| Resume(*v1alpha1.AnalysisRun, v1alpha1.Metric, v1alpha1.Measurement) v1alpha1.Measurement | ||
| // Terminate will terminate an in-progress measurement | ||
| Terminate(*v1alpha1.AnalysisRun, v1alpha1.Metric, v1alpha1.Measurement) v1alpha1.Measurement | ||
| // GarbageCollect is used to garbage collect completed measurements to the specified limit | ||
| GarbageCollect(*v1alpha1.AnalysisRun, v1alpha1.Metric, int) RpcError | ||
| // Type gets the provider type | ||
| Type() string | ||
| // GetMetadata returns any additional metadata which providers need to store/display as part | ||
| // of the metric result. For example, Prometheus uses is to store the final resolved queries. | ||
| GetMetadata(metric v1alpha1.Metric) map[string]string | ||
| } | ||
| type TrafficRouterPlugin interface { | ||
| // InitPlugin initializes the traffic router plugin this gets called once when the plugin is loaded. | ||
| InitPlugin() RpcError | ||
| // UpdateHash informs a traffic routing reconciler about new canary, stable, and additionalDestination(s) pod hashes | ||
| UpdateHash(rollout *v1alpha1.Rollout, canaryHash, stableHash string, additionalDestinations []v1alpha1.WeightDestination) RpcError | ||
| // SetWeight sets the canary weight to the desired weight | ||
| SetWeight(rollout *v1alpha1.Rollout, desiredWeight int32, additionalDestinations []v1alpha1.WeightDestination) RpcError | ||
| // SetHeaderRoute sets the header routing step | ||
| SetHeaderRoute(rollout *v1alpha1.Rollout, setHeaderRoute *v1alpha1.SetHeaderRoute) RpcError | ||
| // SetMirrorRoute sets up the traffic router to mirror traffic to a service | ||
| SetMirrorRoute(rollout *v1alpha1.Rollout, setMirrorRoute *v1alpha1.SetMirrorRoute) RpcError | ||
| // VerifyWeight returns true if the canary is at the desired weight and additionalDestinations are at the weights specified | ||
| // Returns nil if weight verification is not supported or not applicable | ||
| VerifyWeight(rollout *v1alpha1.Rollout, desiredWeight int32, additionalDestinations []v1alpha1.WeightDestination) (RpcVerified, RpcError) | ||
| // RemoveManagedRoutes Removes all routes that are managed by rollouts by looking at spec.strategy.canary.trafficRouting.managedRoutes | ||
| RemoveManagedRoutes(ro *v1alpha1.Rollout) RpcError | ||
| // Type returns the type of the traffic routing reconciler | ||
| Type() string | ||
| } | ||
| ``` | ||
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| ## Plugin Init Function | ||
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| Each plugin interface has a `InitPlugin` function, this function is called when the plugin is first started up and is only called | ||
| once per startup. The `InitPlugin` function is used as a means to initialize the plugin it gives you the plugin author the ability | ||
| to either set up a client for a specific metrics provider or in the case of a traffic router construct a client or informer | ||
| for kubernetes api. The one thing to note about this though is because these calls happen over RPC the plugin author should | ||
| not depend on state being stored in the plugin struct as it will not be persisted between calls. | ||
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| ## Kubernetes RBAC | ||
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| The plugin runs as a child process of the rollouts controller and as such it will inherit the same RBAC permissions as the | ||
| controller. This means that the service account for the rollouts controller will need the correct permissions for the plugin | ||
| to function. This might mean instructing users to create a role and role binding to the standard rollouts service account | ||
| for the plugin to use. This will probably affect traffic router plugins more than metrics plugins. | ||
|
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| ## Sample Plugins | ||
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| There are two sample plugins within the argo-rollouts repo that you can use as a reference for creating your own plugin. | ||
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| * [Sample Metrics Plugin](https://github.com/argoproj/argo-rollouts/tree/master/test/cmd/sample-metrics-plugin) | ||
| * [Sample Traffic Router Plugin](https://github.com/argoproj/argo-rollouts/tree/master/test/cmd/sample-trafficrouter-plugin) |
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