20755: Allow cloud drivers to register their own metrics.

[arvados.git] / lib / cloud / interfaces.go

// Copyright (C) The Arvados Authors. All rights reserved.
//
// SPDX-License-Identifier: AGPL-3.0

package cloud

import (
        "encoding/json"
        "errors"
        "io"
        "time"

        "git.arvados.org/arvados.git/sdk/go/arvados"
        "github.com/prometheus/client_golang/prometheus"
        "github.com/sirupsen/logrus"
        "golang.org/x/crypto/ssh"
)

// A RateLimitError should be returned by an InstanceSet when the
// cloud service indicates it is rejecting all API calls for some time
// interval.
type RateLimitError interface {
        // Time before which the caller should expect requests to
        // fail.
        EarliestRetry() time.Time
        error
}

// A QuotaError should be returned by an InstanceSet when the cloud
// service indicates the account cannot create more VMs than already
// exist.
type QuotaError interface {
        // If true, don't create more instances until some existing
        // instances are destroyed. If false, don't handle the error
        // as a quota error.
        IsQuotaError() bool
        error
}

type SharedResourceTags map[string]string
type InstanceSetID string
type InstanceTags map[string]string
type InstanceID string
type ImageID string

// An Executor executes commands on an ExecutorTarget.
type Executor interface {
        // Update the set of private keys used to authenticate to
        // targets.
        SetSigners(...ssh.Signer)

        // Set the target used for subsequent command executions.
        SetTarget(ExecutorTarget)

        // Return the current target.
        Target() ExecutorTarget

        // Execute a shell command and return the resulting stdout and
        // stderr. stdin can be nil.
        Execute(cmd string, stdin io.Reader) (stdout, stderr []byte, err error)
}

var ErrNotImplemented = errors.New("not implemented")

// An ExecutorTarget is a remote command execution service.
type ExecutorTarget interface {
        // SSH server hostname or IP address, or empty string if
        // unknown while instance is booting.
        Address() string

        // Remote username to send during SSH authentication.
        RemoteUser() string

        // Return nil if the given public key matches the instance's
        // SSH server key. If the provided Dialer is not nil,
        // VerifyHostKey can use it to make outgoing network
        // connections from the instance -- e.g., to use the cloud's
        // "this instance's metadata" API.
        //
        // Return ErrNotImplemented if no verification mechanism is
        // available.
        VerifyHostKey(ssh.PublicKey, *ssh.Client) error
}

// Instance is implemented by the provider-specific instance types.
type Instance interface {
        ExecutorTarget

        // ID returns the provider's instance ID. It must be stable
        // for the life of the instance.
        ID() InstanceID

        // String typically returns the cloud-provided instance ID.
        String() string

        // Cloud provider's "instance type" ID. Matches a ProviderType
        // in the cluster's InstanceTypes configuration.
        ProviderType() string

        // Get current tags
        Tags() InstanceTags

        // Replace tags with the given tags
        SetTags(InstanceTags) error

        // Get recent price history, if available. The InstanceType is
        // supplied as an argument so the driver implementation can
        // account for AddedScratch cost without requesting the volume
        // attachment information from the provider's API.
        PriceHistory(arvados.InstanceType) []InstancePrice

        // Shut down the node
        Destroy() error
}

// An InstanceSet manages a set of VM instances created by an elastic
// cloud provider like AWS, GCE, or Azure.
//
// All public methods of an InstanceSet, and all public methods of the
// instances it returns, are goroutine safe.
type InstanceSet interface {
        // Create a new instance with the given type, image, and
        // initial set of tags. If supported by the driver, add the
        // provided public key to /root/.ssh/authorized_keys.
        //
        // The given InitCommand should be executed on the newly
        // created instance. This is optional for a driver whose
        // instances' VerifyHostKey() method never returns
        // ErrNotImplemented. InitCommand will be under 1 KiB.
        //
        // The returned error should implement RateLimitError and
        // QuotaError where applicable.
        Create(arvados.InstanceType, ImageID, InstanceTags, InitCommand, ssh.PublicKey) (Instance, error)

        // Return all instances, including ones that are booting or
        // shutting down. Optionally, filter out nodes that don't have
        // all of the given InstanceTags (the caller will ignore these
        // anyway).
        //
        // An instance returned by successive calls to Instances() may
        // -- but does not need to -- be represented by the same
        // Instance object each time. Thus, the caller is responsible
        // for de-duplicating the returned instances by comparing the
        // InstanceIDs returned by the instances' ID() methods.
        Instances(InstanceTags) ([]Instance, error)

        // Stop any background tasks and release other resources.
        Stop()
}

type InstancePrice struct {
        StartTime time.Time
        Price     float64
}

type InitCommand string

// A Driver returns an InstanceSet that uses the given InstanceSetID
// and driver-dependent configuration parameters.
//
// If the driver creates cloud resources that aren't attached to a
// single VM instance (like SSH key pairs on AWS) and support tagging,
// they should be tagged with the provided SharedResourceTags.
//
// The supplied id will be of the form "zzzzz-zzzzz-zzzzzzzzzzzzzzz"
// where each z can be any alphanum. The returned InstanceSet must use
// this id to tag long-lived cloud resources that it creates, and must
// assume control of any existing resources that are tagged with the
// same id. Tagging can be accomplished by including the ID in
// resource names, using the cloud provider's tagging feature, or any
// other mechanism. The tags must be visible to another instance of
// the same driver running on a different host.
//
// The returned InstanceSet must not modify or delete cloud resources
// unless they are tagged with the given InstanceSetID or the caller
// (dispatcher) calls Destroy() on them. It may log a summary of
// untagged resources once at startup, though. Thus, two identically
// configured InstanceSets running on different hosts with different
// ids should log about the existence of each other's resources at
// startup, but will not interfere with each other.
//
// The dispatcher always passes the InstanceSetID as a tag when
// calling Create() and Instances(), so the driver does not need to
// tag/filter VMs by InstanceSetID itself.
//
// Example:
//
//      type exampleInstanceSet struct {
//              ownID     string
//              AccessKey string
//      }
//
//      type exampleDriver struct {}
//
//      func (*exampleDriver) InstanceSet(config json.RawMessage, id cloud.InstanceSetID, tags cloud.SharedResourceTags, logger logrus.FieldLogger, reg *prometheus.Registry) (cloud.InstanceSet, error) {
//              var is exampleInstanceSet
//              if err := json.Unmarshal(config, &is); err != nil {
//                      return nil, err
//              }
//              is.ownID = id
//              return &is, nil
//      }
type Driver interface {
        InstanceSet(config json.RawMessage, id InstanceSetID, tags SharedResourceTags, logger logrus.FieldLogger, reg *prometheus.Registry) (InstanceSet, error)
}

// DriverFunc makes a Driver using the provided function as its
// InstanceSet method. This is similar to http.HandlerFunc.
func DriverFunc(fn func(config json.RawMessage, id InstanceSetID, tags SharedResourceTags, logger logrus.FieldLogger, reg *prometheus.Registry) (InstanceSet, error)) Driver {
        return driverFunc(fn)
}

type driverFunc func(config json.RawMessage, id InstanceSetID, tags SharedResourceTags, logger logrus.FieldLogger, reg *prometheus.Registry) (InstanceSet, error)

func (df driverFunc) InstanceSet(config json.RawMessage, id InstanceSetID, tags SharedResourceTags, logger logrus.FieldLogger, reg *prometheus.Registry) (InstanceSet, error) {
        return df(config, id, tags, logger, reg)
}