HON95-wiki/config/linux-general/applications.md

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title: Linux Applications breadcrumbs:

• title: Configuration
• title: Linux General --- {% include header.md %}

Docker

Setup

1. Install: Docker Documentation: Get Docker Engine - Community for Debian.
2. (Optional) Setup swap limit:
   • If docker info contains WARNING: No swap limit support, it's not working and should maybe be fixed.
   • It incurs a small performance degredation and is optional but recommended.
   • In /etc/default/grub, add cgroup_enable=memory swapaccount=1 to GRUB_CMDLINE_LINUX.
   • Run update-grub and reboot.
3. Configure /etc/docker/daemon.json:
   • Enable IPv6: "ipv6": true and "fixed-cidr-v6": "<ipv6-subnet>/64"
     • Note that IPv6 it not NATed like IPv4 is in Docker.
   • Set DNS servers: "dns": ["1.1.1.1", "1.0.0.1", "2606:4700:4700::1111", "2606:4700:4700::1001"]
     • If not set, containers will use 8.8.8.8 and 8.8.4.4 by default.
   • (Optional) Disable automatic IPTables rules: "iptables": false
4. (Optional, not recommended on servers) Allow certain users to use Docker: Add them to the docker group.

Usage

• Miscellanea:
  • Show disk usage: docker system df -v
• Cleanup:
  • Prune unused images: docker image prune -a
  • Prune unused volumes: docker volume prune
• Docker run options:
  • Set name: --name=<name>
  • Run in detatched mode: -d
  • Run using interactive terminal: -it
  • Automatically remove when stopped: --rm
  • Automatically restart: --restart=unless-stopped
  • Use "tini" as entrypoint and use PID 1: --init
  • Set env var: -e <var>=<val>
  • Publish network port: -p <host-port>:<cont-port>[/udp]
  • Mount volume: -v <vol>:<cont-path> (<vol> must have a path prefix like ./ or / if it is a directory and not a named volume)
• Networks:
  • Create simple bridged network: docker network create --driver=bridge --subnet=<ipv4-net> --ipv6 --subnet=<ipv6-net> <name>
  • Create network connected to host bridge: docker network create --driver=bridge --subnet=<ipv4-net> --gateway=<ipv4-gateway> --ipv6 --subnet=<ipv6-net> --gateway=<ipv6-gateway> -o "com.docker.network.bridge.name=<host-if> <name>
  • Create network connected to host interface: docker network create --driver=macvlan --subnet=<ipv4-net> --gateway=<ipv4-gateway> --ipv6 --subnet=<ipv6-net> --gateway=<ipv6-gateway> -o parent=<netif> <name>
  • Run container with network: docker run --network=<net-name> --ip=<ipv4-addr> --ip6=<ipv6-addr> --dns=<dns-server> <image>

Docker Compose

Setup

1. Install Docker: See above.
2. Install: Docker Documentation: Install Docker Compose.
3. Install command completion: Docker Documentation: Command-line completion.

Troubleshooting

Fix Docker Compose No-Exec Tmp-Dir

Docker Compose will fail to work if /tmp has noexec.

1. Move /usr/local/bin/docker-compose to /usr/local/bin/docker-compose-normal.
2. Create /usr/local/bin/docker-compose with the contents below and make it executable.
3. Create the new TMPDIR dir.

New docker-compose:

#!/bin/bash
# Some dir without noexec
export TMPDIR=/var/lib/docker-compose-tmp
/usr/local/bin/docker-compose-normal "$@"

smartmontools

• For monitoring disk health.
• Install: apt install smartmontools
• Show all info: smartctl -a <dev>
• Tests are available in foreground and background mode, where foreground mode is given higher priority.
• Tests:
  • Short test: Can be useful to quickly identify a faulty drive.
  • Long test: May be used to validate the results found in the short test.
  • Convoyance test: Intended to quickly discover damage incurred during transportation/shipping.
  • Select test: Test only the specified LBAs.
• Run test: smartctl -t <short|long|conveyance|select> [-C] <dev>
  • -C: Foreground mode.

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