An in-depth study of HTTP request headers in Golang

Golang (Go language) is an efficient programming language with many features that adjust the entire development experience. In Golang, through the HTTP package provided by the standard library, we can easily make HTTP requests, of which the HTTP request header is also a very important part. In this article, we will take a deep dive into HTTP request headers in Golang.

Basic knowledge of HTTP request headers

First of all, we need to understand the basic knowledge of HTTP request headers. Although each HTTP request header has its own unique purpose and format, we can classify them into the following categories:

Universal headers

Universal headers are applicable to all types Headers for HTTP requests and responses, meaning we can use them in every request and response message. These headers include Cache-Control, Connection, Date, etc. Common headers help us specify cache control, date and time information, and other basic information for HTTP messages.

Request header

HTTP request header is the header information included when sending a request to the server. These headers include Accept, Accept-Encoding, Authorization, etc. They are used to send information associated with the request, such as the type of content that needs to be received, the compression scheme, and certificate information used to authenticate the user.

Response Headers

HTTP response headers are the headers returned by the server in response to a client request. These headers include Server, Content-Type, Content-Length, etc. Response headers provide information used by the server, such as the response's content length, content type, and the operating system and software used by the server.

HTTP request headers in the standard library

In Golang, the net/http package provided in the standard library can easily make HTTP requests. In order to use the HTTP header, we need to specify an http.Transport when instantiating http.Client:

transport := &http.Transport{}
client := &http.Client{
    Transport: transport,
}

Here, an empty Transport is created, which is the minimum requirement for instantiating the Client. Then we can append the header to the request. By calling the http.Header.Set method, we can set the value of an attribute, such as the User-Agent attribute:

req, err := http.NewRequest("GET", url, nil)
req.Header.Set("User-Agent", "Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.2; Trident/6.0)")

Taking the above request as an example, we created an http.NewRequest and specified the HTTP method and URL. Then, we set the User-Agent attribute, which is a common request header that tells the server the name and version of the browser and operating system that sent the request.

In addition, in addition to http.Request, we can also set request headers in the HTTP client through the following methods:

req.Header.Add("Accept-Language", "en-US")
req.Header.Add("Authorization", "Bearer "+authToken)

In the above code snippet, we combine Accept-Language and Authorization header added to our request.

Custom HTTP request header

In addition to using standard request headers, we can also create custom HTTP request headers in Golang. This can be started by using the Add or Set method in the http.Header instance:

header := http.Header{}
header.Set("X-Custom-Header", "my custom header value")

The above code defines a new Header instance and adds a custom HTTP request header named X-Custom-Header . This kind of custom HTTP request header is great for passing client-specific metadata for use in subsequent requests and responses.

Summary

In this article, we learned the basics of HTTP request headers and how to use them in Golang. We learned about the differences between universal headers, request headers, and response headers, and learned how to set and use these headers from the http package in the standard library, as well as how to create our own custom HTTP request headers. If you are developing HTTP-based applications, this article provides some very useful tips and knowledge to better control and manage HTTP requests and responses.

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