copy azcore to master (#6791)

update internal module dependency
remove golint from CI

sdk/azcore/core.go

@@ -0,0 +1,112 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+package azcore
+
+import (
+	"context"
+	"errors"
+	"io"
+	"net/http"
+)
+
+// Policy represents an extensibility point for the Pipeline that can mutate the specified
+// Request and react to the received Response.
+type Policy interface {
+	// Do applies the policy to the specified Request.  When implementing a Policy, mutate the
+	// request before calling req.Do() to move on to the next policy, and respond to the result
+	// before returning to the caller.
+	Do(ctx context.Context, req *Request) (*Response, error)
+}
+
+// PolicyFunc is a type that implements the Policy interface.
+// Use this type when implementing a stateless policy as a first-class function.
+type PolicyFunc func(context.Context, *Request) (*Response, error)
+
+// Do implements the Policy interface on PolicyFunc.
+func (pf PolicyFunc) Do(ctx context.Context, req *Request) (*Response, error) {
+	return pf(ctx, req)
+}
+
+// Transport represents an HTTP pipeline transport used to send HTTP requests and receive responses.
+type Transport interface {
+	// Do sends the HTTP request and returns the HTTP response or error.
+	Do(ctx context.Context, req *http.Request) (*http.Response, error)
+}
+
+// transportFunc is a type that implements the Transport interface.
+// Use this type when implementing a stateless transport as a first-class function.
+type transportFunc func(context.Context, *http.Request) (*http.Response, error)
+
+// Do implements the Transport interface on transportFunc.
+func (tf transportFunc) Do(ctx context.Context, req *http.Request) (*http.Response, error) {
+	return tf(ctx, req)
+}
+
+// used to adapt a TransportPolicy to a Policy
+type transportPolicy struct {
+	trans Transport
+}
+
+func (tp transportPolicy) Do(ctx context.Context, req *Request) (*Response, error) {
+	resp, err := tp.trans.Do(ctx, req.Request)
+	if err != nil {
+		return nil, err
+	}
+	return &Response{Response: resp}, nil
+}
+
+// Pipeline represents a primitive for sending HTTP requests and receiving responses.
+// Its behavior can be extended by specifying policies during construction.
+type Pipeline struct {
+	policies []Policy
+}
+
+// NewPipeline creates a new goroutine-safe Pipeline object from the specified Policies.
+// If no transport is provided then the default HTTP transport will be used.
+func NewPipeline(transport Transport, policies ...Policy) Pipeline {
+	if transport == nil {
+		transport = DefaultHTTPClientTransport()
+	}
+	// transport policy must always be the last in the slice
+	policies = append(policies, newBodyDownloadPolicy(), transportPolicy{trans: transport})
+	return Pipeline{
+		policies: policies,
+	}
+}
+
+// Do is called for each and every HTTP request. It passes the Context and request through
+// all the Policy objects (which can transform the Request's URL/query parameters/headers)
+// and ultimately sends the transformed HTTP request over the network.
+func (p Pipeline) Do(ctx context.Context, req *Request) (*Response, error) {
+	req.policies = p.policies
+	return req.Next(ctx)
+}
+
+// ReadSeekCloser is the interface that groups the io.ReadCloser and io.Seeker interfaces.
+type ReadSeekCloser interface {
+	io.ReadCloser
+	io.Seeker
+}
+
+type nopCloser struct {
+	io.ReadSeeker
+}
+
+func (n nopCloser) Close() error {
+	return nil
+}
+
+// NopCloser returns a ReadSeekCloser with a no-op close method wrapping the provided io.ReadSeeker.
+func NopCloser(rs io.ReadSeeker) ReadSeekCloser {
+	return nopCloser{rs}
+}
+
+// IterationDone is returned by an iterator's Next method when iteration is complete.
+var IterationDone = errors.New("no more items in iterator")
+
+// Retrier provides methods describing if an error should be considered as transient.
+type Retrier interface {
+	// IsNotRetriable returns true for error types that are not retriable.
+	IsNotRetriable() bool
+}

sdk/azcore/credential.go

@@ -0,0 +1,50 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+package azcore
+
+import (
+	"context"
+	"time"
+)
+
+// AuthenticationPolicyOptions contains various options used to create a credential policy.
+type AuthenticationPolicyOptions struct {
+	// Options contains the TokenRequestOptions that includes a scopes field which contains
+	// the list of OAuth2 authentication scopes used when requesting a token.
+	// This field is ignored for other forms of authentication (e.g. shared key).
+	Options TokenRequestOptions
+}
+
+// Credential represents any credential type.
+type Credential interface {
+	// AuthenticationPolicy returns a policy that requests the credential and applies it to the HTTP request.
+	AuthenticationPolicy(options AuthenticationPolicyOptions) Policy
+}
+
+// credentialFunc is a type that implements the Credential interface.
+// Use this type when implementing a stateless credential as a first-class function.
+type credentialFunc func(options AuthenticationPolicyOptions) Policy
+
+// AuthenticationPolicy implements the Credential interface on credentialFunc.
+func (cf credentialFunc) AuthenticationPolicy(options AuthenticationPolicyOptions) Policy {
+	return cf(options)
+}
+
+// TokenCredential represents a credential capable of providing an OAuth token.
+type TokenCredential interface {
+	Credential
+	// GetToken requests an access token for the specified set of scopes.
+	GetToken(ctx context.Context, options TokenRequestOptions) (*AccessToken, error)
+}
+
+// AccessToken represents an Azure service bearer access token with expiry information.
+type AccessToken struct {
+	Token     string
+	ExpiresOn time.Time
+}
+
+// TokenRequestOptions contain specific parameter that may be used by credentials types when attempting to get a token
+type TokenRequestOptions struct {
+	Scopes []string
+}

sdk/azcore/doc.go

@@ -0,0 +1,162 @@
+// Copyright 2017 Microsoft Corporation. All rights reserved.
+// Use of this source code is governed by an MIT
+// license that can be found in the LICENSE file.
+
+/*
+Package azcore implements an HTTP request/response middleware pipeline whose
+policy objects mutate an HTTP request's URL, query parameters, and/or headers before
+the request is sent over the wire.
+
+Not all policy objects mutate an HTTP request; some policy objects simply impact the
+flow of requests/responses by performing operations such as logging, retry policies,
+timeouts, failure injection, and deserialization of response payloads.
+
+Implementing the Policy Interface
+
+To implement a policy, define a struct that implements the pipeline.Policy interface's Do method. Your Do
+method is called when an HTTP request wants to be sent over the network. Your Do method can perform any
+operation(s) it desires. For example, it can log the outgoing request, mutate the URL, headers, and/or query
+parameters, inject a failure, etc. Your Do method must then forward the HTTP request to next Policy object
+in a linked-list ensuring that the remaining Policy objects perform their work. Ultimately, the last Policy
+object sends the HTTP request over the network (by calling the HTTPSender's Do method).
+
+When an HTTP response comes back, each Policy object in the linked-list gets a chance to process the response
+(in reverse order). The Policy object can log the response, retry the operation if due to a transient failure
+or timeout, deserialize the response body, etc. Ultimately, the last Policy object returns the HTTP response
+to the code that initiated the original HTTP request.
+
+Here is a template for how to define a pipeline.Policy object:
+
+   type myPolicy struct {
+      node   PolicyNode
+      // TODO: Add configuration/setting fields here (if desired)...
+   }
+
+   func (p *myPolicy) Do(ctx context.Context, request pipeline.Request) (pipeline.Response, error) {
+      // TODO: Mutate/process the HTTP request here...
+      response, err := p.node.Do(ctx, request)	// Forward HTTP request to next Policy & get HTTP response
+      // TODO: Mutate/process the HTTP response here...
+      return response, err	// Return response/error to previous Policy
+   }
+
+Implementing the Factory Interface
+
+Each Policy struct definition requires a factory struct definition that implements the pipeline.Factory interface's New
+method. The New method is called when application code wants to initiate a new HTTP request. Factory's New method is
+passed a pipeline.PolicyNode object which contains a reference to the owning pipeline.Pipeline object (discussed later) and
+a reference to the next Policy object in the linked list. The New method should create its corresponding Policy object
+passing it the PolicyNode and any other configuration/settings fields appropriate for the specific Policy object.
+
+Here is a template for how to define a pipeline.Policy object:
+
+   // NOTE: Once created & initialized, Factory objects should be goroutine-safe (ex: immutable);
+   // this allows reuse (efficient use of memory) and makes these objects usable by multiple goroutines concurrently.
+   type myPolicyFactory struct {
+      // TODO: Add any configuration/setting fields if desired...
+   }
+
+   func (f *myPolicyFactory) New(node pipeline.PolicyNode) Policy {
+      return &myPolicy{node: node} // TODO: Also initialize any configuration/setting fields here (if desired)...
+   }
+
+Using your Factory and Policy objects via a Pipeline
+
+To use the Factory and Policy objects, an application constructs a slice of Factory objects and passes
+this slice to the pipeline.NewPipeline function.
+
+   func NewPipeline(factories []pipeline.Factory, sender pipeline.HTTPSender) Pipeline
+
+This function also requires an object implementing the HTTPSender interface. For simple scenarios,
+passing nil for HTTPSender causes a standard Go http.Client object to be created and used to actually
+send the HTTP response over the network. For more advanced scenarios, you can pass your own HTTPSender
+object in. This allows sharing of http.Client objects or the use of custom-configured http.Client objects
+or other objects that can simulate the network requests for testing purposes.
+
+Now that you have a pipeline.Pipeline object, you can create a pipeline.Request object (which is a simple
+wrapper around Go's standard http.Request object) and pass it to Pipeline's Do method along with passing a
+context.Context for cancelling the HTTP request (if desired).
+
+   type Pipeline interface {
+      Do(ctx context.Context, methodFactory pipeline.Factory, request pipeline.Request) (pipeline.Response, error)
+   }
+
+Do iterates over the slice of Factory objects and tells each one to create its corresponding
+Policy object. After the linked-list of Policy objects have been created, Do calls the first
+Policy object passing it the Context & HTTP request parameters. These parameters now flow through
+all the Policy objects giving each object a chance to look at and/or mutate the HTTP request.
+The last Policy object sends the message over the network.
+
+When the network operation completes, the HTTP response and error return values pass
+back through the same Policy objects in reverse order. Most Policy objects ignore the
+response/error but some log the result, retry the operation (depending on the exact
+reason the operation failed), or deserialize the response's body. Your own Policy
+objects can do whatever they like when processing outgoing requests or incoming responses.
+
+Note that after an I/O request runs to completion, the Policy objects for that request
+are garbage collected. However, Pipeline object (like Factory objects) are goroutine-safe allowing
+them to be created once and reused over many I/O operations. This allows for efficient use of
+memory and also makes them safely usable by multiple goroutines concurrently.
+
+Inserting a Method-Specific Factory into the Linked-List of Policy Objects
+
+While Pipeline and Factory objects can be reused over many different operations, it is
+common to have special behavior for a specific operation/method. For example, a method
+may need to deserialize the response's body to an instance of a specific data type.
+To accommodate this, the Pipeline's Do method takes an additional method-specific
+Factory object. The Do method tells this Factory to create a Policy object and
+injects this method-specific Policy object into the linked-list of Policy objects.
+
+When creating a Pipeline object, the slice of Factory objects passed must have 1
+(and only 1) entry marking where the method-specific Factory should be injected.
+The Factory marker is obtained by calling the pipeline.MethodFactoryMarker() function:
+
+   func MethodFactoryMarker() pipeline.Factory
+
+Creating an HTTP Request Object
+
+The HTTP request object passed to Pipeline's Do method is not Go's http.Request struct.
+Instead, it is a pipeline.Request struct which is a simple wrapper around Go's standard
+http.Request. You create a pipeline.Request object by calling the pipeline.NewRequest function:
+
+   func NewRequest(method string, url url.URL, options pipeline.RequestOptions) (request pipeline.Request, err error)
+
+To this function, you must pass a pipeline.RequestOptions that looks like this:
+
+   type RequestOptions struct {
+      // The readable and seekable stream to be sent to the server as the request's body.
+      Body io.ReadSeeker
+
+      // The callback method (if not nil) to be invoked to report progress as the stream is uploaded in the HTTP request.
+      Progress ProgressReceiver
+   }
+
+The method and struct ensure that the request's body stream is a read/seekable stream.
+A seekable stream is required so that upon retry, the final Policy object can seek
+the stream back to the beginning before retrying the network request and re-uploading the
+body. In addition, you can associate a ProgressReceiver callback function which will be
+invoked periodically to report progress while bytes are being read from the body stream
+and sent over the network.
+
+Processing the HTTP Response
+
+When an HTTP response comes in from the network, a reference to Go's http.Response struct is
+embedded in a struct that implements the pipeline.Response interface:
+
+   type Response interface {
+      Response() *http.Response
+   }
+
+This interface is returned through all the Policy objects. Each Policy object can call the Response
+interface's Response method to examine (or mutate) the embedded http.Response object.
+
+A Policy object can internally define another struct (implementing the pipeline.Response interface)
+that embeds an http.Response and adds additional fields and return this structure to other Policy
+objects. This allows a Policy object to deserialize the body to some other struct and return the
+original http.Response and the additional struct back through the Policy chain. Other Policy objects
+can see the Response but cannot see the additional struct with the deserialized body. After all the
+Policy objects have returned, the pipeline.Response interface is returned by Pipeline's Do method.
+The caller of this method can perform a type assertion attempting to get back to the struct type
+really returned by the Policy object. If the type assertion is successful, the caller now has
+access to both the http.Response and the deserialized struct object.
+*/
+package azcore

sdk/azcore/error.go

@@ -0,0 +1,51 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+package azcore
+
+import (
+	"errors"
+	"fmt"
+)
+
+var (
+	// ErrNoMorePolicies is returned from Request.Next() if there are no more policies in the pipeline.
+	ErrNoMorePolicies = errors.New("no more policies")
+)
+
+// TODO: capture frame info for marshal, unmarshal, and parsing errors
+// built in frame in xerror?  %w
+type frameInfo struct {
+	file string
+	line int
+}
+
+func (f frameInfo) String() string {
+	if f.zero() {
+		return ""
+	}
+	return fmt.Sprintf("file: %s, line: %d", f.file, f.line)
+}
+
+func (f frameInfo) zero() bool {
+	return f.file == "" && f.line == 0
+}
+
+// RequestError is returned when the service returns an unsuccessful resopnse code (4xx, 5xx).
+type RequestError struct {
+	msg  string
+	resp *Response
+}
+
+func newRequestError(message string, response *Response) error {
+	return RequestError{msg: message, resp: response}
+}
+
+func (re RequestError) Error() string {
+	return re.msg
+}
+
+// Response returns the underlying response.
+func (re RequestError) Response() *Response {
+	return re.resp
+}

sdk/azcore/go.mod

@@ -0,0 +1,5 @@
+module github.com/Azure/azure-sdk-for-go/sdk/azcore
+
+require github.com/Azure/azure-sdk-for-go/sdk/internal v0.1.0
+
+go 1.13

sdk/azcore/go.sum

@@ -0,0 +1,2 @@
+github.com/Azure/azure-sdk-for-go/sdk/internal v0.1.0 h1:sgOdyT1ZAW3nErwCuvlGrkeP03pTtbRBW5MGCXWGZws=
+github.com/Azure/azure-sdk-for-go/sdk/internal v0.1.0/go.mod h1:Q+TCQnSr+clUU0JU+xrHZ3slYCxw17AOFdvWFpQXjAY=