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consul/connect: dynamically select envoy sidecar at runtime
As newer versions of Consul are released, the minimum version of Envoy it supports as a sidecar proxy also gets bumped. Starting with the upcoming Consul v1.9.X series, Envoy v1.11.X will no longer be supported. Current versions of Nomad hardcode a version of Envoy v1.11.2 to be used as the default implementation of Connect sidecar proxy. This PR introduces a change such that each Nomad Client will query its local Consul for a list of Envoy proxies that it supports (hashicorp/consul#8545) and then launch the Connect sidecar proxy task using the latest supported version of Envoy. If the `SupportedProxies` API component is not available from Consul, Nomad will fallback to the old version of Envoy supported by old versions of Consul. Setting the meta configuration option `meta.connect.sidecar_image` or setting the `connect.sidecar_task` stanza will take precedence as is the current behavior for sidecar proxies. Setting the meta configuration option `meta.connect.gateway_image` will take precedence as is the current behavior for connect gateways. `meta.connect.sidecar_image` and `meta.connect.gateway_image` may make use of the special `${NOMAD_envoy_version}` variable interpolation, which resolves to the newest version of Envoy supported by the Consul agent. Addresses #8585 #7665
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,170 @@ | ||
| package taskrunner | ||
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|
||
| import ( | ||
| "context" | ||
| "strings" | ||
|
|
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| "github.com/hashicorp/go-hclog" | ||
| "github.com/hashicorp/go-version" | ||
| ifs "github.com/hashicorp/nomad/client/allocrunner/interfaces" | ||
| "github.com/hashicorp/nomad/client/consul" | ||
| "github.com/hashicorp/nomad/nomad/structs" | ||
| "github.com/pkg/errors" | ||
| ) | ||
|
|
||
| const ( | ||
| // envoyVersionHookName is the name of this hook and appears in logs. | ||
| envoyVersionHookName = "envoy_version" | ||
|
|
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| // envoyLegacyImage is used when the version of Consul is too old to support | ||
| // the SupportedProxies field in the self API. | ||
| // | ||
| // This is the version defaulted by Nomad before v0.13.0 and/or when using versions | ||
| // of Consul before v1.7.8, v1.8.5, and v1.9.0. | ||
| envoyLegacyImage = "envoyproxy/envoy:v1.11.2@sha256:a7769160c9c1a55bb8d07a3b71ce5d64f72b1f665f10d81aa1581bc3cf850d09" | ||
| ) | ||
|
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| type envoyVersionHookConfig struct { | ||
| alloc *structs.Allocation | ||
| proxiesClient consul.SupportedProxiesAPI | ||
| logger hclog.Logger | ||
| } | ||
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| func newEnvoyVersionHookConfig(alloc *structs.Allocation, proxiesClient consul.SupportedProxiesAPI, logger hclog.Logger) *envoyVersionHookConfig { | ||
| return &envoyVersionHookConfig{ | ||
| alloc: alloc, | ||
| logger: logger, | ||
| proxiesClient: proxiesClient, | ||
| } | ||
| } | ||
|
|
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| // envoyVersionHook is used to determine and set the Docker image used for Consul | ||
| // Connect sidecar proxy tasks. It will query Consul for a set of preferred Envoy | ||
| // versions if the task image is unset or references ${NOMAD_envoy_version}. Nomad | ||
| // will fallback the image to the previous default Envoy v1.11.2 if Consul is too old | ||
| // to support the supported proxies API. | ||
| type envoyVersionHook struct { | ||
| // alloc is the allocation with the envoy task being rewritten. | ||
| alloc *structs.Allocation | ||
|
|
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| // proxiesClient is the subset of the Consul API for getting information | ||
| // from Consul about the versions of Envoy it supports. | ||
| proxiesClient consul.SupportedProxiesAPI | ||
|
|
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| // logger is used to log things. | ||
| logger hclog.Logger | ||
| } | ||
|
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| func newEnvoyVersionHook(c *envoyVersionHookConfig) *envoyVersionHook { | ||
| return &envoyVersionHook{ | ||
| alloc: c.alloc, | ||
| proxiesClient: c.proxiesClient, | ||
| logger: c.logger.Named(envoyVersionHookName), | ||
| } | ||
| } | ||
|
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| func (envoyVersionHook) Name() string { | ||
| return envoyVersionHookName | ||
| } | ||
|
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| func (h *envoyVersionHook) Prestart(_ context.Context, request *ifs.TaskPrestartRequest, response *ifs.TaskPrestartResponse) error { | ||
| if h.skip(request) { | ||
| response.Done = true | ||
| return nil | ||
| } | ||
|
|
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| // We either need to acquire Consul's preferred Envoy version or fallback | ||
| // to the legacy default. Query Consul and use the (possibly empty) result. | ||
| proxies, err := h.proxiesClient.Proxies() | ||
| if err != nil { | ||
| return errors.Wrap(err, "error retrieving supported Envoy versions from Consul") | ||
| } | ||
|
|
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| // Determine the concrete Envoy image identifier by applying version string | ||
| // substitution (${NOMAD_envoy_version}). | ||
| image, err := h.tweakImage(h.taskImage(request.Task.Config), proxies) | ||
| if err != nil { | ||
| return errors.Wrap(err, "error interpreting desired Envoy version from Consul") | ||
| } | ||
|
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| // Set the resulting image. | ||
| h.logger.Trace("setting task envoy image", "image", image) | ||
| request.Task.Config["image"] = image | ||
| response.Done = true | ||
| return nil | ||
| } | ||
|
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| // skip will return true if the request does not contain a task that should have | ||
| // its envoy proxy version resolved automatically. | ||
| func (h *envoyVersionHook) skip(request *ifs.TaskPrestartRequest) bool { | ||
| switch { | ||
| case request.Task.Driver != "docker": | ||
| return true | ||
| case !request.Task.UsesConnectSidecar(): | ||
| return true | ||
| case !h.needsVersion(request.Task.Config): | ||
| return true | ||
| } | ||
| return false | ||
| } | ||
|
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| // getConfiguredImage extracts the configured config.image value from the request. | ||
| // If the image is empty or not a string, Nomad will fallback to the normal | ||
| // official Envoy image as if the setting was not configured. This is also what | ||
| // Nomad would do if the sidecar_task was not set in the first place. | ||
| func (_ *envoyVersionHook) taskImage(config map[string]interface{}) string { | ||
| value, exists := config["image"] | ||
| if !exists { | ||
| return structs.EnvoyImageFormat | ||
| } | ||
|
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| image, ok := value.(string) | ||
| if !ok { | ||
| return structs.EnvoyImageFormat | ||
| } | ||
|
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| return image | ||
| } | ||
|
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| // needsVersion returns true if the docker.config.image is making use of the | ||
| // ${NOMAD_envoy_version} faux environment variable. | ||
| // Nomad does not need to query Consul to get the preferred Envoy version, etc.) | ||
| func (h *envoyVersionHook) needsVersion(config map[string]interface{}) bool { | ||
| if len(config) == 0 { | ||
| return false | ||
| } | ||
|
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| image := h.taskImage(config) | ||
|
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| return strings.Contains(image, structs.EnvoyVersionVar) | ||
| } | ||
|
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| // image determines the best Envoy version to use. If supported is nil or empty | ||
| // Nomad will fallback to the legacy envoy image used before Nomad v0.13. | ||
| func (_ *envoyVersionHook) tweakImage(configured string, supported map[string][]string) (string, error) { | ||
| versions := supported["envoy"] | ||
| if len(versions) == 0 { | ||
| return envoyLegacyImage, nil | ||
| } | ||
|
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| latest, err := semver(versions[0]) | ||
| if err != nil { | ||
| return "", err | ||
| } | ||
|
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| return strings.ReplaceAll(configured, structs.EnvoyVersionVar, latest), nil | ||
| } | ||
|
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| // semver sanitizes the envoy version string coming from Consul into the format | ||
| // used by the Envoy project when publishing images (i.e. proper semver). This | ||
| // resulting string value does NOT contain the 'v' prefix for 2 reasons: | ||
| // 1) the version library does not include the 'v' | ||
| // 2) its plausible unofficial images use the 3 numbers without the prefix for | ||
| // tagging their own images | ||
| func semver(chosen string) (string, error) { | ||
| v, err := version.NewVersion(chosen) | ||
| if err != nil { | ||
| return "", errors.Wrap(err, "unexpected envoy version format") | ||
| } | ||
| return v.String(), nil | ||
| } |
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