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runtime: add debug console service

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Add `kata-runtime exec` to enter guest OS
through shell started by agent

Fixes: #245

Signed-off-by: bin liu <bin@hyper.sh>
This commit is contained in:
bin liu
2020-07-16 16:13:05 +08:00
parent 594519d883
commit febdf8f68c
17 changed files with 578 additions and 65 deletions
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51
docs/Developer-Guide.md
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@@ -34,7 +34,11 @@
* [Troubleshoot Kata Containers](#troubleshoot-kata-containers)
* [Appendices](#appendices)
* [Checking Docker default runtime](#checking-docker-default-runtime)
* [Set up a debug console](#set-up-a-debug-console)
* [Set up a debug console(the easy way)](#set-up-a-debug-consolethe-easy-way)
* [Enable agent debug console](#enable-agent-debug-console)
* [Start `kata-monitor`](#start-kata-monitor)
* [Connect to debug console](#connect-to-debug-console)
* [Set up a debug console(the traditional way)](#set-up-a-debug-consolethe-traditional-way)
* [Create a custom image containing a shell](#create-a-custom-image-containing-a-shell)
* [Create a debug systemd service](#create-a-debug-systemd-service)
* [Build the debug image](#build-the-debug-image)
@@ -60,7 +64,7 @@ The recommended way to create a development environment is to first
to create a working system.
The installation guide instructions will install all required Kata Containers
components, plus Docker*, the hypervisor, and the Kata Containers image and
components, plus *Docker*, the hypervisor, and the Kata Containers image and
guest kernel.
# Requirements to build individual components
@@ -434,7 +438,48 @@ See [Set up a debug console](#set-up-a-debug-console).
$ sudo docker info 2>/dev/null | grep -i "default runtime" | cut -d: -f2- | grep -q runc && echo "SUCCESS" || echo "ERROR: Incorrect default Docker runtime"
```
## Set up a debug console
## Set up a debug console(The easy way)
Kata containers 2.0 support a shell simulated *console* for quickly debug purpose. This approach use `vsock` to connect shell running inside guest started by agent. The good aspect is that we need not modify guest image or despite using what device that hypervisors support. Only `/bin/sh` or `/bin/bash` are necessary.
### Enable agent debug console
Change your `configuration.toml`, add agent debug parameters.
```
kernel_params = "agent.debug_console agent.debug_console_vport=1026"
```
Sandboxes created using this parameters will start a shell in guest if new connection is accept from `vsock`.
### Start `kata-monitor`
`kata-runitime exec` need `kata-monitor` to get the sandbox's `vsock` address to connect to, firt start `kata-monitor`.
```
$ sudo kata-monitor
```
`kata-monitor` will serve at `localhost:8090` by default.
### Connect to debug console
Command `kata-runitime exec` is used to connect to the debug console.
```
$ kata-runtime exec 1a9ab65be63b8b03dfd0c75036d27f0ed09eab38abb45337fea83acd3cd7bacd
bash-4.2# id
uid=0(root) gid=0(root) groups=0(root)
bash-4.2# pwd
/
bash-4.2# exit
exit
```
If you want to access guest OS through a traditional way, see [Set up a debug console(the traditional way)](#set-up-a-debug-console-the-traditional-way).
## Set up a debug console(the traditional way)
By default you cannot login to a virtual machine, since this can be sensitive
from a security perspective. Also, allowing logins would require additional