Site Reliability Engineer Blog

Hi guys,
this is day 18 out of 100 days of code.

To get md5 sum of a file you crypto/md5 library and io/ioutil for reading files.

package main

import (
	"crypto/md5"
	"fmt"
	"io/ioutil"
	"log"
	"os"
)

func main() {
	if len(os.Args) <= 1 {
		log.Fatal("expected filename as parameter")
	}
	filename := os.Args[1]

	data, err := ioutil.ReadFile(filename)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("MD5 (%s) = %x\n", filename, md5.Sum(data))
}

Thanks!

Hi guys,
this is day 16 out of 100 days of code.

With help of http and ioutil packages file download and storage is quite easy task.

package main

import (
	"io/ioutil"
	"log"
	"net/http"
)

func main() {
	url := "https://picsum.photos/200/300/?random"

	resp, err := http.Get(url)
	if err != nil {
		log.Fatal(err)
	}
	defer resp.Body.Close()

	image, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		log.Fatal(err)
	}
	err = ioutil.WriteFile("./myimage.gif", image, 0644)
	if err != nil {
		log.Fatal(err)
	}
}

In the example I am using Lorem Picsum service to get random image every run.

Happy coding!

Hi guys,
today is day 13 out of 100 days of code in go!

This time it is example of fetching issues from github and categorizing by created date.
To run example you need to install github issue searcher package from The Go Progamming Language book

go get gopl.io/ch4/github

Full code

package main

import (
	"fmt"
	"log"
	"os"
	"time"

	"gopl.io/ch4/github"
)

func main() {
	result, err := github.SearchIssues(os.Args[1:])
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("%d issues:\n", result.TotalCount)
	var dateformat string
	for _, item := range result.Items {
		days := int(time.Since(item.CreatedAt).Hours()) / 24
		if days < 30 {
			dateformat = "less than a month old"
		} else if days < 365 {
			dateformat = "less than a year old"
		} else {
			dateformat = "more than a year old"
		}
		fmt.Printf("%s, #%-5d %9.9s %.55s\n", dateformat, item.Number, item.User.Login, item.Title)
	}
}

Happy coding!

Hi guys,
this is day 12 out of 100 days of code. I didn’t post for a while, because I did a small break for hackaton, but now I am back on track.

When you print a map using range function it will access elements in randomized order. So, if you want to print map in sorted order you have to sort keys first. See how:

package main

import (
	"fmt"
	"sort"
)

func main() {
	m := map[string]int{"A": 1, "B": 2, "AA": 1, "C": 3, "BBB": 2}

	//reverse keys and values of m map
	var mapKeys []string
	fmt.Print("Unsorted:\n")
	for k, v := range m {
		fmt.Printf("%s -> %d\n", k, v)
		mapKeys = append(mapKeys, k)
	}

	sort.Strings(mapKeys)
	fmt.Print("Sorted:\n")
	for _, v := range mapKeys {
		fmt.Printf("%s -> %d\n", v, m[v])
	}
}

Solution is to use additional array for keys and sort it in wished order.

Happy coding!

Hi guys,
this is day 11 out of 100 days of go coding.

This time it is very short demo of go maps and simple sort by map values. Note that the example below will not work correctly if values has duplicates.

package main

import (
	"fmt"
	"sort"
)

func main() {
        //init a map with strings keys and int values
	var m = make(map[string]int)
	m["Sun"] = 7
	m["Sat"] = 6
	m["Fri"] = 5
	m["Thu"] = 4
	m["Mon"] = 1
	m["Tue"] = 2
	m["Wed"] = 3

	//reverse keys and values of m map
	var days = make(map[int]string)
	//array of indexes for sorting
	var daykeys = make([]int, len(m))

	fmt.Print("Unsorted days of week\n")
	counter := 0
	for k, v := range m {
		fmt.Printf("%s -> %d\n", k, v)
		days[v] = k
		daykeys[counter] = v
		counter++
	}
	//sort indexes array here
	sort.Ints(daykeys)

	fmt.Print("Sorted days of week\n")
	for _, v := range daykeys {
		fmt.Printf("%s\n", days[v])
	}
}

I believe this code has a lot of room for optimization, so if you know how please write me in comments or ping me in twitter with your version.

Happy coding everyone!