A place to share my gained knowledge and experience

Quan Tong

"Life is all about sharing. If we are good at something, pass it on." - Mary Berry

Bị theo dõi (Permanent Record) - Edward Snowden

2020-07-15

6 tuổi: vặn đồng hồ chậm lại để chơi cho đã
7 tuổi: tháo tung con máy Nintendo ra vì đang chơi Super Mario thì bị hỏng
7 tuổi rưỡi: chép những dòng code “Hello world” đầu tiên trong một lần được đến công ty ba chơi
12 tuổi: làm quen với máy tính trên chiếc Compaq Presario 425 (Intel 486, ổ cứng 200MB)
13 tuổi: hack website của Phòng thí nghiệm Quốc gia Los Alamos (sau đó thì được cảm ơn và hẹn liên lạc lại khi nào 18 tuổi)

Save draft mail in Zimbra web client using ChromeDP

2020-07-03

As an engineer, I want to automate everything as much as possible. This CLI tool is created to save a draft mail in Zimbra web client.

Read config file:

 1func initConfig() {
 2	if cfgFile != "" {
 3		// Use config file from the flag.
 4		viper.SetConfigFile(cfgFile)
 5	} else {
 6		// Find home directory.
 7		home, err := homedir.Dir()
 8		if err != nil {
 9			fmt.Println(err)
10			os.Exit(1)
11		}
12
13		// Search config in home directory with name ".zwc" (without extension).
14		viper.AddConfigPath(home)
15		viper.SetConfigName(".zwc")
16	}
17
18	viper.AutomaticEnv() // read in environment variables that match
19
20	// If a config file is found, read it in.
21	if err := viper.ReadInConfig(); err != nil {
22		log.Fatal(err)
23	}
24
25	fmt.Println("Using config file:", viper.ConfigFileUsed())
26}

How to trigger build steps based on modified directory?

2020-06-26

Using monorepo with multiple micro services, every single commit will trigger a full lint/test/build/publish for every service. What can I do to limit the scope?

To do that, we can use git diff to show changes between commits:

 1  if [[ -n "${DRONE_PULL_REQUEST}" ]]; then
 2    most_recent_before="origin/${DRONE_TARGET_BRANCH}"
 3  elif [[ "${DRONE_BUILD_EVENT}" = "push" && ("${DRONE_COMMIT_BRANCH}" = "master" || "${DRONE_COMMIT_BRANCH}" = "release-"*) ]]; then
 4    if [[ "${DRONE_COMMIT_BEFORE}" = "$zero" ]]; then
 5      exit 0
 6    else
 7      most_recent_before="${DRONE_COMMIT_BEFORE}"
 8    fi
 9  fi
10  modified_files=$(git --no-pager diff --name-only "${DRONE_COMMIT_SHA}".."${most_recent_before}");

Hanoi tour

2020-05-16

The big church, Hanoi.

Hà Nội Tour (nửa ngày, 0 đêm):

6h30: các bạn được đánh thức bởi tiếng nhạc du dương: https://www.youtube.com/watch?v=QMEt8_7uBhY
6h35: di chuyển bằng xe “căng hải” từ phòng ngủ ra William C.
6h45: trang phục tự chọn
7h: lúc này “xe ôm” đã đứng ở dưới để sẵn sàng phục vụ.
7h30: các bạn đang có mặt ở Phan Đình Phùng, một trong những con đường đẹp nhất HN. Tại đây, các bạn thoải mái chụp hình, ngắm lá vàng trong ánh nắng đầu hè dễ chịu.

Drone build is not triggered after pushing code to Gitea?

2020-05-06

I pushed code to Gitea and nothing happens in Drone. Why?

But if I go to Settings -> Webhooks, then click “Test Delivery” -> build pipeline will be executed. Why?

First, look at the “Recent Deliveries” to see if a webhook is triggerd here when you pushing code. In my case, it’s not. So, looks like the problem is on Gitea side.

By pay close attention to the git output when pushing:

 1Counting objects: 4, done.
 2Delta compression using up to 4 threads.
 3Compressing objects: 100% (4/4), done.
 4Writing objects: 100% (4/4), 2.02 KiB | 2.02 MiB/s, done.
 5Total 4 (delta 2), reused 0 (delta 0)
 6hint: The 'hooks/pre-receive' hook was ignored because it's not set as executable.
 7hint: You can disable this warning with `git config advice.ignoredHook false`.
 8hint: The 'hooks/update' hook was ignored because it's not set as executable.
 9hint: You can disable this warning with `git config advice.ignoredHook false`.
10hint: The 'hooks/post-receive' hook was ignored because it's not set as executable.
11hint: You can disable this warning with `git config advice.ignoredHook false`.
12To gitea.pi:quanta/blog.git
13 + d29f63d...47e9ed3 master -> master (forced update)

How a gRPC message uses length-prefixed framing?

2020-05-06

Once we have the encoded data to send to the other end, we need to package the data in a way that other end can easily extract the information. gRPC uses a message framing technique called length-prefixed framing.

Filter gRPC messages:

1$ tshark -r grpc.pcapng -Y 'grpc'

Find out a stream: DATA:

1216 923.033355    127.0.0.1 → 127.0.0.1    GRPC 108 DATA[1] (GRPC) (PROTOBUF)

and show the packet details:

1tshark -r grpc.pcapng -Y "frame.number == 216" -V

How to show all HTTP2 headers using tshark?

2020-05-05

After sniffing with tcpdump, how can I show all HTTP2 header using tshark?

First, find the frame number based on method:

1$ tshark -r grpc.pcapng -Y 'http2.headers.path contains "getBook"'
2214 923.033174    127.0.0.1 → 127.0.0.1    HTTP2 150 HEADERS[1]: POST /book.BookInfo/getBook

and then show the packet details:

 1tshark -r grpc.pcapng -Y "frame.number == 214" -V
 2
 3HyperText Transfer Protocol 2
 4    Stream: HEADERS, Stream ID: 1, Length 85, POST /book.BookInfo/getBook
 5        Length: 85
 6        Type: HEADERS (1)
 7        Flags: 0x04
 8            .... ...0 = End Stream: False
 9            .... .1.. = End Headers: True
10            .... 0... = Padded: False
11            ..0. .... = Priority: False
12            00.0 ..0. = Unused: 0x00
13        0... .... .... .... .... .... .... .... = Reserved: 0x0
14        .000 0000 0000 0000 0000 0000 0000 0001 = Stream Identifier: 1
15        [Pad Length: 0]
16        Header Block Fragment: 8386459162339faaf74e7eb92a94ec4c54dd39faff418b08…
17        [Header Length: 216]
18        [Header Count: 8]
19        Header: :method: POST
20            Name Length: 7
21            Name: :method
22            Value Length: 4
23            Value: POST
24            :method: POST
25            [Unescaped: POST]
26            Representation: Indexed Header Field
27            Index: 3
28        Header: :scheme: http
29            Name Length: 7
30            Name: :scheme
31            Value Length: 4
32            Value: http
33            :scheme: http
34            [Unescaped: http]
35            Representation: Indexed Header Field
36            Index: 6
37        Header: :path: /book.BookInfo/getBook
38            Name Length: 5
39            Name: :path
40            Value Length: 22
41            Value: /book.BookInfo/getBook
42            :path: /book.BookInfo/getBook
43            [Unescaped: /book.BookInfo/getBook]
44            Representation: Literal Header Field with Incremental Indexing - Indexed Name
45            Index: 5
46        Header: :authority: 127.0.0.1:50051
47            Name Length: 10
48            Name: :authority
49            Value Length: 15
50            Value: 127.0.0.1:50051
51            :authority: 127.0.0.1:50051
52            [Unescaped: 127.0.0.1:50051]
53            Representation: Literal Header Field with Incremental Indexing - Indexed Name
54            Index: 1
55        Header: content-type: application/grpc
56            Name Length: 12
57            Name: content-type
58            Value Length: 16
59            Value: application/grpc
60            content-type: application/grpc
61            [Unescaped: application/grpc]
62            Representation: Literal Header Field with Incremental Indexing - Indexed Name
63            Index: 31
64        Header: user-agent: grpc-go/1.24.0
65            Name Length: 10
66            Name: user-agent
67            Value Length: 14
68            Value: grpc-go/1.24.0
69            user-agent: grpc-go/1.24.0
70            [Unescaped: grpc-go/1.24.0]
71            Representation: Literal Header Field with Incremental Indexing - Indexed Name
72            Index: 58
73        Header: te: trailers
74            Name Length: 2
75            Name: te
76            Value Length: 8
77            Value: trailers
78            [Unescaped: trailers]
79            Representation: Literal Header Field with Incremental Indexing - New Name
80        Header: grpc-client: evans
81            Name Length: 11
82            Name: grpc-client
83            Value Length: 5
84            Value: evans
85            [Unescaped: evans]
86            Representation: Literal Header Field with Incremental Indexing - New Name

brew info gets stuck

2020-04-25

I managed my Mac with SaltStack.

For some reasons, it gets stuck when running brew state:

1[INFO    ] Executing command '/usr/local/bin/brew info --json=v1 --installed' as user 'quanta' in directory '/Users/quanta'

As usual, whenever you get a problem, let’s enable debug mode to see what happens:

1brew info --json=v1 --installed -d

Now I can see that it stucked at drone/drone repo. By just untap this repo, and it’s solved.

Google Calendar CLI

2020-04-13

Our company allows us to work from home some days a week. To do that, we have to create an event in Google Calendar.

I created this tool to run it from CLI.

First, take a look at this quickstart.

Create initical code by running:

1$ cobra init
2
3$ tree -L 2
4.
5├── LICENSE
6├── cmd
7│   └── root.go
8├── main.go

Create event command:

 1$ cobra add event
 2$ cobra add insert -p 'eventCmd'
 3
 4$ tree -L 2
 5.
 6├── LICENSE
 7├── cmd
 8│   ├── event.go
 9│   ├── event_insert.go
10│   └── root.go
11├── main.go

Kể tên 10 ứng dụng mà bạn muốn có

2020-04-12

Tổng hợp các co-working spaces ở Hà Nội, gửi mail khi có khuyến mại
Ước lượng thời gian đi từ A đến B, kết hợp với tình hình thời tiết xem có nên đi không
Chia sẻ tài liệu, cách thực hành, … để cải thiện khả năng nghĩ ra các ý tưởng
Tự động đặt lịch rửa xe nếu cả tuần tới không mưa
Ứng dụng cho phép mọi người ghi lại những khó khăn trong công việc hàng ngày để người khác hoặc chính họ tìm cách giải quyết

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