https://github.com/yankeguo/minit
The missing init daemon for container
https://github.com/yankeguo/minit
containers docker golang init kubernetes
Last synced: 19 days ago
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The missing init daemon for container
- Host: GitHub
- URL: https://github.com/yankeguo/minit
- Owner: yankeguo
- License: mit
- Created: 2022-09-29T06:33:17.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2025-11-13T10:05:54.000Z (5 months ago)
- Last Synced: 2025-11-13T12:07:06.520Z (5 months ago)
- Topics: containers, docker, golang, init, kubernetes
- Language: Go
- Homepage:
- Size: 1.62 MB
- Stars: 4
- Watchers: 1
- Forks: 1
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
- Security: SECURITY.md
Awesome Lists containing this project
README
# minit
[](https://github.com/yankeguo/minit/actions/workflows/release.yml)
[](https://hub.docker.com/r/yankeguo/minit)
The missing `init` daemon for container
[中文文档](README.zh.md)
## 1. Installation
You can install `minit` to your own container image by a multi-stage `Dockerfile`
```dockerfile
FROM yankeguo/minit:VERSION AS minit
# Or using Github Packages
# FROM ghcr.io/yankeguo/minit:VERSION AS minit
# Your own build stage
FROM ubuntu:22.04
# ...
# Copy minit binary
COPY --from=minit /minit /minit
# Set ENTRYPOINT to minit
ENTRYPOINT ["/minit"]
# Add a unit file to /etc/minit.d
ADD my-service.yml /etc/minit.d/my-service.yml
```
## 2. Unit Loading
### 2.1 From Files
Add Unit `YAML` files to `/etc/minit.d`
Override default directory by environment variable `MINIT_UNIT_DIR`, multiple directories are supported by separating with `:`
Use `---` to separate multiple units in single `YAML` file
### 2.2 From Environment Variable
#### Prefix with `MINIT_UNIT_XXXX_`
**Example:**
```dockerfile
ENV MINIT_UNIT_MAIN_COMMAND="redis-server /etc/redis.conf"
ENV MINIT_UNIT_MAIN_DIR="/work"
ENV MINIT_UNIT_MAIN_NAME="main-program"
ENV MINIT_UNIT_MAIN_GROUP="super-main"
ENV MINIT_UNIT_MAIN_KIND="cron"
ENV MINIT_UNIT_MAIN_IMMEDIATE=true
ENV MINIT_UNIT_MAIN_CRON="* * * * *"
ENV MINIT_UNIT_MAIN_CHARSET=gbk18030
```
#### DEPRECATED: `MINIT_MAIN`
```dockerfile
ENV MINIT_MAIN="redis-server /etc/redis.conf"
ENV MINIT_MAIN_DIR="/work"
ENV MINIT_MAIN_NAME="main-program"
ENV MINIT_MAIN_GROUP="super-main"
ENV MINIT_MAIN_KIND="cron"
ENV MINIT_MAIN_IMMEDIATE=true
ENV MINIT_MAIN_CRON="* * * * *"
ENV MINIT_MAIN_CHARSET=gbk18030
```
### 2.3 From Command Arguments
**Example:**
```dockerfile
ENTRYPOINT ["/minit"]
CMD ["redis-server", "/etc/redis.conf"]
```
### 2.4 Unit Order
For `render` and `once` units, `minit` will load them in a specific order
**Source Order**
- Units loaded from files
- Units loaded from environment variables
- Units loaded from command arguments
**Type Order**
- `render`
- `once`
**Order in Same Type**
- Order in files
- Order in environment variables
**Override**
Set field `order` to override default order.
`order` is an integer, lower value will be loaded first.
`order` with minus value will be loaded before default order.
`order` with positive value will be loaded after default order.
## 3. Unit Types
### 3.1 Type: `render`
`render` units execute at the very first stage. It renders template files.
See [pkg/mtmpl/funcs.go](pkg/mtmpl/funcs.go) for available functions.
**Example:**
- `/etc/minit.d/render-demo.yaml`
```yaml
kind: render
name: render-demo
files:
- /opt/*.txt # inline rendering
- /opt/source.txt:/opt/target.txt # file-to-file or dir-to-dir
- /opt/source/dir:*.txt:/opt/target/dir # source dir to target dir (three parts)
```
- `/opt/demo.txt`
```text
Hello, {{stringsToUpper .Env.HOME}}
```
Upon startup, `minit` will render file `/opt/demo.txt`
Since default user for container is `root`, the content of file `/opt/demo.txt` will become:
```text
Hello, ROOT
```
### 3.2 Type: `once`
`once` units execute after `render` units. It runs command once.
**Example:**
```yaml
kind: once
name: once-demo
command:
- echo
- once
```
**Non-blocking**
By default, `once` units will block other `minit` units until finished.
Set `blocking: false` to run `once` units in background.
**Critical**
If `critical` field is set to `true`, `minit` will stop if this unit failed.
### 3.3 Type: `daemon`
`daemon` units execute after `render` and `once`. It runs long-running command.
**Example:**
```yaml
kind: daemon
name: daemon-demo
command:
- sleep
- 9999
```
### 3.4 Type: `cron`
`cron` units execute after `render` and `once`. It runs command at cron basis.
**Example:**
```yaml
kind: cron
name: cron-demo
cron: "* * * * *" # cron expression, support extended syntax by https://github.com/robfig/cron
immediate: true # execute once on started
command:
- echo
- cron
```
environment variable substitution is supported in `cron` field, for example:
```yaml
cron: $MY_SCHEDULE
```
## 4. Unit Features
### 4.1 Replicas
If `count` field is set, `minit` will replicate this unit with sequence number suffixed
**Example:**
```yaml
kind: once
name: once-demo-replicas
count: 2
command:
- echo
- $MINIT_UNIT_SUB_ID
```
Is equal to:
```yaml
kind: once
name: once-demo-replicas-1
command:
- echo
- 1
---
kind: once
name: once-demo-replicas-2
command:
- echo
- 2
```
### 4.2 Logging
**Log Files**
By default `minit` only streams console logs of every command unit into it's own stdout/stderr.
Set `MINIT_LOG_DIR` to enable file logging, for example: `MINIT_LOG_DIR=/var/log/minit`
**Console Encoding**
If `charset` field is set, `minit` will transcode command console output from other encodings to `utf8`
**Example:**
```yaml
kind: once
name: once-demo-transcode
charset: gbk # supports gbk, gb18030 only
command:
- command-that-produces-gbk-logs
```
### 4.3 Extra Environment Variables
If `env` field is set, `minit` will append extra environment variables while launching command.
**Example:**
```yaml
kind: daemon
name: daemon-demo-env
env:
AAA: BBB
command:
- echo
- $AAA
```
### 4.4 Render Environment Variables
Any environment with prefix `MINIT_ENV_` will be rendered before passing to command.
**Example:**
```yaml
kind: daemon
name: daemon-demo-render-env
env:
MINIT_ENV_MY_IP: '{{netResolveIP "google.com"}}'
command:
- echo
- $MY_IP
```
### 4.5 Using `shell` in command units
By default, `command` field will be passed to `exec` syscall, `minit` won't modify ti, except simple environment variable substitution.
If `shell` field is set, `command` field will act as a simple script file.
**Example:**
```yaml
kind: once
name: once-demo-shell
shell: "/bin/bash -eu"
command: # this is merely a script file
- if [ -n "${HELLO}" ]; then
- echo "world"
- fi
```
### 4.6 Unit Enabling / Disabling
**Grouping**
Use `group` field to set a group name to units.
Default unit group name is `default`
**Allowlist Mode**
If environment `MINIT_ENABLE` is set, `minit` will run in **Allowlist Mode**, only units with name existed
in `MINIT_ENABLE` will be loaded.
Use format `@group-name` to enable a group of units
Use format `&daemon` to enable a kind of units
Example:
```text
MINIT_ENABLE=once-demo,@demo
```
**Denylist Mode**
If environment `MINIT_DISABLE` is set, `minit` will run in **Denylist Mode**, units with name existed in `MINIT_DISABLE`
will NOT be loaded.
Use format `@group-name` to disable a group of units
Example:
```text
MINIT_DISABLE=once-demo,@demo
```
## 4.7 Critical Units
If `critical` field is set to `true`, `minit` will stop if this unit failed.
By specifying the `success_codes` field for `once`, `daemon` and `cron` units, `minit` will interpret exit codes within the provided list as indicative of success.
Example:
```yaml
kind: once
name: once-demo-critical
critical: true
command:
- false
---
kind: once
name: once-demo-critical
critical: true
success_codes:
- 0
- 1
command:
- false
```
## 5. Extra Features
### 5.1 Zombie Processes Cleaning
When running as `PID 1`, `minit` will do zombie process cleaning
This is the responsibility of `PID 1`
### 5.2 Quick Exit
By default, `minit` will keep running even without `daemon` or `cron` units defined.
If you want to use `minit` in `initContainers` or outside of container, you can set envrionment
variable `MINIT_QUIT_EXIT=true` to let `minit` exit as soon as possible
### 5.3 Resource limits (ulimit)
**Warning: this feature need container running at Privileged mode**
Use environment variable `MINIT_RLIMIT_XXX` to set resource limits
- `unlimited` means no limitation
- `-` means unchanged
**Supported:**
```text
MINIT_RLIMIT_AS
MINIT_RLIMIT_CORE
MINIT_RLIMIT_CPU
MINIT_RLIMIT_DATA
MINIT_RLIMIT_FSIZE
MINIT_RLIMIT_LOCKS
MINIT_RLIMIT_MEMLOCK
MINIT_RLIMIT_MSGQUEUE
MINIT_RLIMIT_NICE
MINIT_RLIMIT_NOFILE
MINIT_RLIMIT_NPROC
MINIT_RLIMIT_RTPRIO
MINIT_RLIMIT_SIGPENDING
MINIT_RLIMIT_STACK
```
**Example:**
```text
MINIT_RLIMIT_NOFILE=unlimited # set soft limit and hard limit to 'unlimited'
MINIT_RLIMIT_NOFILE=128:unlimited # set soft limit to 128，set hard limit to 'unlimited'
MINIT_RLIMIT_NOFILE=128:- # set soft limit to 128，dont change hard limit
MINIT_RLIMIT_NOFILE=-:unlimited # don't change soft limit，set hard limit to 'unlimited'
```
### 5.4 Kernel Parameters (sysctl)
**Warning: this feature need container running at Privileged mode**
Use environment variable `MINIT_SYSCTL` to set kernel parameters
Separate multiple entries with `,`
**Example:**
```
MINIT_SYSCTL=vm.max_map_count=262144,vm.swappiness=60
```
### 5.5 Transparent Huge Page (THP)
**Warning: this feature need container running at Privileged mode and host `/sys` mounted**
Use environment variable `MINIT_THP` to set THP configuration.
**Example:**
```
# available values: never, madvise, always
MINIT_THP=madvise
```
### 5.6 Built-in WebDAV server
By setting environment variable `MINIT_WEBDAV_ROOT`, `minit` will start a built-in WebDAV server at port `7486`
Environment Variables:
- `MINIT_WEBDAV_ROOT`, path to serve, `/srv` for example
- `MINIT_WEBDAV_PORT`, port of WebDAV server, default to `7486`
- `MINIT_WEBDAV_USERNAME` and `MINIT_WEBDAV_PASSWORD`, optional basic auth for WebDAV server
### 5.7 Banner file
By putting a file at `/etc/banner.minit.txt`, `minit` will print it's content at startup
## 6. Credits
GUO YANKE, MIT License