Exec

exec a command in container

ExecCreate

creates a new exec configuration to run an exec process

HTTP Request

POST /api/v1/namespaces/default/pods/{podName}/exec?container={containerName}

Path Parameters

Parameter	Description
podName	name of pod

Query Parameters

Parameter	Description
containerName	name of container

Body Parameters

Parameter

PodExecConfig

$ pi exec nginx -c nginx -- echo hello
//Post Data
{"tty":false,"attachStdin":false,"attachStderr":true,"attachStdout":true, "cmd":["echo","hello"]}

$ pi exec nginx -it -c nginx -- sh
//Post Data
{"tty":true,"attachStdin":true,"attachStderr":true,"attachStdout":true,"cmd":["sh"]}

Response

Code	Description
201 PodExecCreateResponse	OK
400	Bad Request
404	Not Found
500	Server Error

{
  "Id": "exec-mtaUcLDzRk"
}

ExecStart

starts an exec process already created

HTTP Request

POST /api/v1/exec/{execID}/start

Path Parameters

Parameter	Description
execID	id of exec process

Body Parameters

Parameter

PodExecConfig

Response

Code	Description
101	No error, hints proxy about hijacking
200	No error, no upgrade header found
400	Bad Request
404	Not Found
500	Server Error

Stream details:

When using the TTY setting is enabled in POST /api/v1/exec/{execID}/start , the stream is the raw data from the process PTY and client's stdin. When the TTY is disabled, then the stream is multiplexed to separate stdout and stderr.

The format is a Header and a Payload (frame).

HEADER

The header contains the information which the stream writes (stdout or stderr). It also contains the size of the associated frame encoded in the last four bytes (uint32).

It is encoded on the first eight bytes like this:

header := [8]byte{STREAM_TYPE, 0, 0, 0, SIZE1, SIZE2, SIZE3, SIZE4}

STREAM_TYPE can be:

0: stdin (is written on stdout)
1: stdout
2: stderr

SIZE1, SIZE2, SIZE3, SIZE4 are the four bytes of the uint32 size encoded as big endian.

PAYLOAD

The payload is the raw stream.

IMPLEMENTATION

The simplest way to implement the Attach protocol is the following:

1. Read eight bytes.

2. Choose stdout or stderr depending on the first byte.

3. Extract the frame size from the last four bytes.

4. Read the extracted size and output it on the correct output.

5. Goto 1.

ExecResize

changes the size of the tty

HTTP Request

POST /api/v1/exec/{execID}/resize?h={height}&w={width}

Path Parameters

Parameter	Description
execID	id of exec process

Query Parameters

Parameter	Description
height	tty height
width	tty width