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https://github.com/seletskiy/hastur
Zero-configuration containers under systemd using systemd-nspawn
https://github.com/seletskiy/hastur
Last synced: 2 months ago
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Zero-configuration containers under systemd using systemd-nspawn
- Host: GitHub
- URL: https://github.com/seletskiy/hastur
- Owner: seletskiy
- Created: 2015-09-28T15:55:18.000Z (over 9 years ago)
- Default Branch: master
- Last Pushed: 2022-01-22T21:10:59.000Z (almost 3 years ago)
- Last Synced: 2024-06-12T09:42:02.588Z (7 months ago)
- Language: Go
- Homepage:
- Size: 57.6 KB
- Stars: 227
- Watchers: 9
- Forks: 9
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
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README
hastur is a tool for launching systemd-nspawn containers without the need for
manual configuration.
It will setup networking, a base root FS and even an overlay FS for containers
automatically.
The primary usecase for hastur is supporting testcases for distributed systems
and running a local set of trusted containers.
# Motivation
systemd-nspawn is useful tool, which can create and run lightweight containers
without any additional software, because it's available out-of-the-box systemd.
However, it requires some configuration to run a working container, such as
managing the network configuration, and downloading and extracting packages.
hastur offers all this configuration automatically, which makes it possible to
run fully-configured systemd-nspawn containers in seconds.
# Installation
## Arch Linux
hastur is available for Arch Linux (for now, only) through the AUR:
https://aur4.archlinux.org/packages/hastur/
## go get
hastur is also go-gettable:
```
go get github.com/seletskiy/hastur
```
# Usage
## Testing water
The most simple usage is testing hastur out-of-the-box: you can tell it to
create an ephemeral container with a basic set of packages:
```
sudo hastur -S
```
After invoking that command, you will end up ~~in Cthulhu's void~~ in the bash
shell.
This test container will be deleted after you exit its shell.
## Creating non-ephemeral containers
Passing the `-k` flag will tell hastur to keep the container after exit:
```
sudo hastur -kS
```
If you don't like the fantastical autogenerated names, you can pass the flag
`-n`:
```
sudo hastur -Sn my-cool-name
```
Note that ephemeral containers are only the ones that both have autogenerated
names and were not started with the `-k` flag.
## Networking
hastur will take care of setting up the networking by creating a bridge and
setting up a shared network. By default, hastur will automatically generate IP
addresses, and you can see a container's address either in its starting message
or by running the query command:
```
sudo hastur -Q
```
You can specify your own IP address by passing the `-a` flag, like this:
```
sudo hastur -S -a 10.0.0.2/8
```
## But what about software?
hastur uses package-based container configurations and will happily populate
your container with the packages that you want. You can use the `-p` flag for
this:
```
sudo hastur -S -p nginx
```
That will create a container with the `nginx` package pre-installed. In
actuality, hastur uses overlays to keep base dirs separate from container data.
The base dirs, or, if you like, images, are just prepared root filesystems,
which have pre-installed packages. You can query the cached base dirs by
running hastur with the `-Qi` flag:
```
sudo hastur -Qi
```
In fact, from hastur's standpoint, a container is just a data dir, which gets
overlayed on top of a root filesystem and then given network capability, so
it will not remember what IP address a container has or what set of packages it
has installed if you forget to specify the correct options.
For example:
```
sudo hastur -Sn test -p git -- /bin/git --version
```
Will output:
```
git version 2.5.3
```
But running this container the next time without `-p git` will tell you that
git is not installed:
```
sudo hastur -Sn test -- /bin/git --version
```
This outputs:
```
No such file or directory
```
However, this `test` container will have a separate FS and all data files will
persist across the two runs.
# Additional information
hastur can operate over several root directories and keep container instances
separately from each other. The `-r` flag is used for this:
```
sudo hastur -r solar-system -Sn earth
sudo hastur -r solar-system -Sn moon
sudo hastur -r alpha-centauri -Sn a
sudo hastur -r alpha-centauri -Sn b
sudo hastur -r alpha-centauri -Sn c
```
The output will be different for these two commands:
```
sudo hastur -r solar-system -Q
sudo hastur -r alpha-centauri -Q
```
The first one will list only the `earth` and `moon` containers, and the second
will only list the `a`, `b` and `c` containers.
# License
MIT.