
# Azure Go Management SDK Guideline

Azure Go management SDK follows the [new Azure SDK guidelines](https://azure.github.io/azure-sdk/general_introduction.html), try to create easy-to-use APIs that are idiomatic, compatible, and dependable.

You can find the full list of management modules [here](https://pkg.go.dev/github.com/Azure/azure-sdk-for-go/sdk).

In this guideline, we will give some instructions about the API usage pattern as well as trouble shooting method. For those are new to management Go SDK, please refer to [quickstart](https://github.com/Azure/azure-sdk-for-go/blob/main/documentation/development/ARM/new-version-quickstart.md). For those migrate from older versions of management Go SDK, please refer to [migration guide](https://aka.ms/azsdk/go/mgmt/migration).

## Table of contents

* [Pageable Operations](#pageable-operations)
* [Long-Running Operations](#long-running-operations)
* [Troubleshooting](#troubleshooting)
* [Major Version Upgrade](#major-version-upgrade)

## Pageable Operations

### General usage

Pageable operations return final data over multiple GET requests. Each GET will receive a page of data consisting of a slice of items. You need to use New*Pager to create a pager helper for all pageable operations. With the returned `*runtime.Pager[T]`, you can fetch pages and determine if there are more pages to fetch. For examples:

```go
import "github.com/Azure/azure-sdk-for-go/sdk/resourcemanager/resources/armresources"
```

```go
ctx := context.TODO() // your context
pager := rgClient.NewListPager(nil)
var resourceGroups []*armresources.ResourceGroup
for pager.More() {
    nextResult, err := pager.NextPage(ctx)
    if err != nil {
        // handle error...
    }
    if nextResult.ResourceGroupListResult.Value != nil {
        resourceGroups = append(resourceGroups, nextResult.ResourceGroupListResult.Value...)
    }
}
// dealing with `resourceGroups`
```

> NOTE: No IO calls are made until the NextPage() method is invoked. The read consistency across pages is determined by the service implement.

### Reference

For more information, you can refer to [design guidelines of Paging](https://azure.github.io/azure-sdk/golang_introduction.html#methods-returning-collections-paging) and [API reference of pager](https://pkg.go.dev/github.com/Azure/azure-sdk-for-go/sdk/azcore/runtime#Pager).

## Long-Running Operations

### General usage

Some operations can take a long time to complete. Azure introduces the long-running operations (LROs) to do such operations asynchronously. You need to use Begin* to start an LRO. It will return a poller that can used to keep polling for the result until LRO is done. For examples:

```go
ctx := context.TODO() // your context
poller, err := client.BeginCreate(ctx, "resource_identifier", "additonal_parameter", nil)
if err != nil {
    // handle error...
}
resp, err = poller.PollUntilDone(ctx, nil)
if err != nil {
    // handle error...
}
// dealing with `resp`
```

### Resume Tokens

Pollers provide the ability to serialize their state into a "resume token" which can be used by another process to recreate the poller. For example:

```go
import "github.com/Azure/azure-sdk-for-go/sdk/resourcemanager/resources/armresources"
```

```go
ctx := context.TODO() // your context
poller, err := client.BeginCreate(ctx, "resource_identifier", "additonal_parameter", nil)
if err != nil {
    // handle error...
}
token, err := poller.ResumeToken()
if err != nil {
    // handle error...
}

// ... 

// recreate the poller from the token
poller, err = client.BeginCreate(ctx, "", "", &armresources.ResourceGroupsClientBeginCreateOptions{
    ResumeToken: token,
})
resp, err = poller.PollUntilDone(ctx, nil)
if err != nil {
    // handle error...
}
// dealing with `resp`
```

> NOTE: A token can only be obtained for a poller that's not in `Succeeded`, `Failed` or `Canceled` state. Each time you call `poller.Poll()`, the token might change because of the LRO state's change. So if you need to cache the token for crash consistency, you need to update the cache when calling `poller.Poll()`.

### Synchronized wrapper

If you do not care about the underlaying detail about the LRO, you can use the following generic utility to create an synchronized wrapper for all LRO.

> NOTE: The error return of `Wait` includes the error of starting LRO and error of interval polling. Also, the wrapper will hide the `poller` which means you cannot recovery from an LRO accidentally interrupt. 

***Synchronized wrapper utility***

```go
import "github.com/Azure/azure-sdk-for-go/sdk/azcore/runtime"
```

```go
type OperationWaiter[TResult any] struct {
    poller *runtime.Poller[TResult]
    err    error
}

func (ow OperationWaiter[TResult]) Wait(ctx context.Context, freq time.Duration) (TResult, error) {
    if ow.err != nil {
        return *new(TResult), ow.err
    }
    return ow.poller.PollUntilDone(ctx, freq)
}

func NewOperationWaiter[TResult any](poller *runtime.Poller[TResult], err error) OperationWaiter[TResult] {
    return OperationWaiter[TResult]{poller: poller, err: err}
}
```

***Usage***

```go
ctx := context.TODO() // your context
resp, err := NewOperationWaiter(client.BeginCreate(ctx, "resource_identifier", "additonal_parameter", nil)).Wait(ctx, time.Second)
// dealing with `resp`
```
### Reference

For more information, you can refer to [design guidelines of LRO](https://azure.github.io/azure-sdk/golang_introduction.html#methods-invoking-long-running-operations) and [API reference of poller](https://pkg.go.dev/github.com/Azure/azure-sdk-for-go/sdk/azcore/runtime#Poller).

## Client Options

### Request Retry Policy
The SDK provides a baked in retry policy for failed requests with default values that can be configured by `arm.ClientOptions.Retry`. For example:

```go
import "github.com/Azure/azure-sdk-for-go/sdk/azcore/arm"
import "github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
import "github.com/Azure/azure-sdk-for-go/sdk/resourcemanager/resources/armresources"
```

```go
clientFactory, err := armresources.NewClientFactory(subscriptionId, credential,
    &arm.ClientOptions{
        ClientOptions: policy.ClientOptions{
            Retry: policy.RetryOptions{
                // retry for 5 times
                MaxRetries: 5,
            },
        },
    },
)
if err != nil {
    log.Fatal(err)
}
rgClient := clientFactory.NewResourceGroupsClient()
```

### Customized Policy

You can use `arm.ClientOptions.PerCallPolicies` and `arm.ClientOptions.PerRetryPolicies` option to inject customized policies to the pipeline. You can refer to `azcore` [document](https://pkg.go.dev/github.com/Azure/azure-sdk-for-go/sdk/azcore) for further information.

### Custom HTTP Client

You can use `arm.ClientOptions.Transport` to set your own implementation of HTTP client. The HTTP client must implement the `policy.Transporter` interface. For example:

```go
import "github.com/Azure/azure-sdk-for-go/sdk/azcore/arm"
import "github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
import "github.com/Azure/azure-sdk-for-go/sdk/resourcemanager/resources/armresources"
```

```go
// your own implementation of HTTP client
httpClient := NewYourOwnHTTPClient{}
clientFactory, err := armresources.NewClientFactory(subscriptionId, credential,
    &arm.ClientOptions{
        ClientOptions: policy.ClientOptions{
            Transport: &httpClient,
        },
    },
)
if err != nil {
    log.Fatal(err)
}
rgClient := clientFactory.NewResourceGroupsClient()
```

### Reference

More client options can be found [here](https://github.com/Azure/azure-sdk-for-go/blob/main/sdk/azcore/policy/policy.go).


## Troubleshooting

### Logging

The SDK uses the classification-based logging implementation in `azcore`. To enable console logging for all SDK modules, please set environment variable `AZURE_SDK_GO_LOGGING` to `all`. 

You can use `policy.LogOption` to configure the logging behavior. For example:

```go
import "github.com/Azure/azure-sdk-for-go/sdk/azcore/arm"
import "github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
import "github.com/Azure/azure-sdk-for-go/sdk/resourcemanager/resources/armresources"
```

```go
clientFactory, err := armresources.NewClientFactory(subscriptionId, credential,
    &arm.ClientOptions{
        ClientOptions: policy.ClientOptions{
            Logging: policy.LogOptions{
                // include HTTP body for log
                IncludeBody: true,
            },
        },
    },
)
if err != nil {
    log.Fatal(err)
}
rgClient := clientFactory.NewResourceGroupsClient()
```

You could use the `azcore/log` package to control log event and redirect log to the desired location. For example:

```go
import azlog "github.com/Azure/azure-sdk-for-go/sdk/azcore/log"
import "github.com/Azure/azure-sdk-for-go/sdk/azidentity"
```

```go
// print log output to stdout
azlog.SetListener(func(event azlog.Event, s string) {
    fmt.Println(s)
})

// include only azidentity credential logs
azlog.SetEvents(azidentity.EventAuthentication)
```

### Raw HTTP response

- You can always get the raw HTTP response from request context regardless of request result.

```go
import "github.com/Azure/azure-sdk-for-go/sdk/azcore"
import "github.com/Azure/azure-sdk-for-go/sdk/azcore/runtime"
```

```go
var rawResponse *http.Response
ctx := context.TODO() // your context
ctxWithResp := runtime.WithCaptureResponse(ctx, &rawResponse)
resp, err := resourceGroupsClient.CreateOrUpdate(ctxWithResp, resourceGroupName, resourceGroupParameters, nil)
if err != nil {
    log.Printf("Status code: %d", rawResponse.StatusCode)
    log.Fatalf("Error occurred: %+v", err)
}
log.Printf("Status code: %d", rawResponse.StatusCode)
```

- When there is an error in the SDK request, you can also convert the error to the `azcore.ResponseError` interface to get the raw HTTP response.

```go
import "github.com/Azure/azure-sdk-for-go/sdk/azcore"
import "github.com/Azure/azure-sdk-for-go/sdk/azcore/runtime"
```

```go
ctx := context.TODO() // your context
resp, err := resourceGroupsClient.CreateOrUpdate(ctx, resourceGroupName, resourceGroupParameters, nil)
if err != nil {
    var respErr *azcore.ResponseError
    if errors.As(err, &respErr) {
        log.Fatalf("Status code: %d", respErr.RawResponse.StatusCode)
    } else {
        log.Fatalf("Other error: %+v", err)
    }
}
// dealing with `resp`
```

## Major Version Upgrade

Go uses [semantic import versioning](https://github.com/golang/go/wiki/Modules#semantic-import-versioning) to ensure a good backward compatibility for modules. For Azure Go management SDK, we usually upgrade module version according to cooresponding service's API version. Regarding it could be a complicated experience for major version upgrade, we will try our best to keep the SDK API stable and release new version in backward compatible way. However, if any unavoidable breaking changes and a new major version releases for SDK modules, you could use these commands under your module folder to upgrade:

```sh
go install github.com/icholy/gomajor@latest
gomajor get github.com/Azure/azure-sdk-for-go/sdk/resourcemanager/compute/armcompute@latest
```

## Need help?

- File an issue via [Github Issues](https://github.com/Azure/azure-sdk-for-go/issues)
- Check [previous questions](https://stackoverflow.com/questions/tagged/azure+go) or ask new ones on StackOverflow using azure and Go tags.

## Contributing

For details on contributing to this repository, see the [contributing guide](https://github.com/Azure/azure-sdk-for-go/blob/main/CONTRIBUTING.md).

This project welcomes contributions and suggestions. Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution. For details, please visit https://cla.microsoft.com.

When you submit a pull request, a CLA-bot will automatically determine whether you need to provide a CLA and decorate the PR appropriately (e.g., label, comment). Simply follow the instructions provided by the
bot. You will only need to do this once across all repositories using our CLA.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact [opencode@microsoft.com](mailto:opencode@microsoft.com) with any questions or comments.
