Add stuff from askiiart/pc-configs

docs/Docker/fix-apipa-veth.md

@@ -0,0 +1,26 @@
+# Fix APIPA (veth)
+
+## Problem
+
+On Debian 11, when:
+
+1. Using docker containers that use the `host` network mode.
+2. `PreferredTechnologies` is set to `ethernet,[...]` in `/etc/connman/main.conf`.
+   - This may not be a problem when ethernet is plugged in, not just wifi.
+
+The system **uses a veth interface** to connect to the internet, which uses an APIPA (169.254.*.*) IP address, so the system can only contact devices on the LAN.
+
+## Solution
+
+Edit `/etc/connman/main.conf` and uncomment the line `# NetworkInterfaceBlacklist = vmnet,vboxnet,virbr,ifb,ve-,vb-`
+
+Result:
+
+```conf
+NetworkInterfaceBlacklist = vmnet,vboxnet,virbr,ifb,ve-,vb-
+```
+
+## References
+
+- [A tale of Docker and Linux ConnMan](https://sitaram.substack.com/p/a-tale-of-docker-and-linux-connman)
+- [Arch Linux Docs](https://wiki.archlinux.org/title/ConnMan#Blacklist_interfaces)

docs/Docker/move-volume.md

@@ -0,0 +1,24 @@
+# Move Docker program data
+
+Docker stores all its data in `/var/lib/docker` by default. This is usually fine, but this directory grows quickly, so we'll move it to `/mnt/big-stuff/docker-program-data/`
+
+Edit `/lib/systemd/system/docker.service` and add the `--data-root` option to the ExecStart line:
+
+```sh
+ExecStart=/usr/bin/dockerd --data-root /mnt/big-stuff/docker-program-data/ -H fd:// $DOCKER_OPTS
+```
+
+If you've already done stuff with docker, you'll need to move the data:
+
+```sh
+sudo systemctl stop docker
+sudo mv /var/lib/docker/ /mnt/big-stuff/docker-program-data/
+sudo systemctl daemon-reload
+sudo systemctl start docker
+```
+
+You may also need to set up some symlinks:
+
+```bash
+ln -s source_file link_file
+```

docs/Docker/resource.limits.md

@@ -0,0 +1,44 @@
+# Resource limits
+
+You can limit the amount of CPU and/or memory resources that a container can use.
+
+## CPU
+
+| Option | Description |
+|--------|-------------|
+| `--cpus` | Set number of CPUs thee container can use |
+| `--cpu-period` | Limits the length of time it can schedule the CPU before being throttled (used alongside `--cpu-quota`) |
+| `--cpu-quota` | The throttling setting activated when the CPU is scheduled longer than `--cpu-period` |
+| `--cpuset-cpus` | Limit the container to specific CPUs or cores (e.g. 0-3, 0,1) |
+| `--cpu-shares` | The number of relative shares of the CPU the container can use (default 1024) |
+
+## Memory
+
+A markdown table:
+
+| Option | Description |
+|--------|-------------|
+| `-m` or `--memory` | Memory limit (minimum 6m (megabytes)) |
+| `--memory-swap` | How much swap is available - [details](https://docs.docker.com/config/containers/resource_constraints/#--memory-swap-details) |
+| `--memory-swappiness` | "By default, the host kernel can swap out a percentage of anonymous pages used by a container. You can set --memory-swappiness to a value between 0 and 100, to tune this percentage" - [details]() |
+| `--memory-reservation` | Soft limit less than `--memory` (for when there is low memory on host), *soft* limit, so usage may exceed this. |
+| `--oom-kill-disable` | Disable OOM Killer (stops from killing container processes when out-of-memory error occurs) - Make sure to use `-m`, or host processes could be killed |
+
+## Example
+
+Note: `--xxxx 4` in `docker run` would be replaced with `xxxx` in `docker-compose.yml`. See below:
+
+```yml
+service:
+  image: nginx
+  mem_limit: 512m
+  mem_reservation: 128M
+  cpus: 0.5
+  ports:
+    - "80:80"
+```
+
+## See also
+
+- [Docker documentation](https://docs.docker.com/config/containers/resource_constraints/)
+- [Baeldung docs](https://www.baeldung.com/ops/docker-memory-limit) (includes `docker compose` examples)

docs/Docker/restart-policies.md

@@ -0,0 +1,27 @@
+# Restart Policies
+
+Restart policies control whether and how Docker attempts to restart a container.
+
+| option | description |
+| ------ | --- |
+| no | does not restart automatically |
+| on-failure[:max-retry] | restarts only when the container exits with a non-zero exit code, and when it has been restarted fewer than max-retry times. |
+| always | always restarts the container if it stops. If it is manually stopped, it is restarted only when Docker daemon restarts or the container itself is manually restarted. |
+| unless-stopped - always restarts the container unless it is manually stopped. Does not restart when the docker daemon is restarted. |
+
+If no restart policy is provided, the default is no.
+
+## Example
+
+```yaml
+version: '3.3'
+services:
+    simple-torrent:
+        ports:
+            - '3000:3000'
+        volumes:
+            - '/path/to/my/downloads:/downloads'
+            - '/path/to/my/torrents:/torrents'
+        image: boypt/cloud-torrent
+        restart: unless-stopped
+```