pct.adoc

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   2 PVE({manvolnum})
   3 ================
   4 include::attributes.txt[]
   5
   6 NAME
   7 ----
   8
   9 pct - Tool to manage Linux Containers (LXC) on Proxmox VE
  10
  11
  12 SYNOPSYS
  13 --------
  14
  15 include::pct.1-synopsis.adoc[]
  16
  17 DESCRIPTION
  18 -----------
  19 endif::manvolnum[]
  20
  21 ifndef::manvolnum[]
  22 Proxmox Container Toolkit
  23 =========================
  24 include::attributes.txt[]
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  26
  27
  28 Containers are a lightweight alternative to fully virtualized
  29 VMs. Instead of emulating a complete Operating System (OS), containers
  30 simply use the OS of the host they run on. This implies that all
  31 containers use the same kernel, and that they can access resources
  32 from the host directly.
  33
  34 This is great because containers do not waste CPU power nor memory due
  35 to kernel emulation. Container run-time costs are close to zero and
  36 usually negligible. But there are also some drawbacks you need to
  37 consider:
  38
  39 * You can only run Linux based OS inside containers, i.e. it is not
  40   possible to run Free BSD or MS Windows inside.
  41
  42 * For security reasons, access to host resources need to be
  43   restricted. This is done with AppArmor, SecComp filters and other
  44   kernel feature. Be prepared that some syscalls are not allowed
  45   inside containers.
  46
  47 {pve} uses https://linuxcontainers.org/[LXC] as underlying container
  48 technology. We consider LXC as low-level library, which provides
  49 countless options. It would be to difficult to use those tools
  50 directly. Instead, we provide a small wrapper called `pct`, the
  51 "Proxmox Container Toolkit".
  52
  53 The toolkit it tightly coupled with {pve}. That means that it is aware
  54 of the cluster setup, and it can use the same network and storage
  55 resources as fully virtualized VMs. You can even use the {pve}
  56 firewall, or manage containers using the HA framework.
  57
  58 Our primary goal is to offer an environment as one would get from a
  59 VM, but without the additional overhead. We call this "System
  60 Containers".
  61
  62 NOTE: If you want to run micro-containers with docker, it is best to
  63 run them inside a VM.
  64
  65
  66 Security Considerations
  67 -----------------------
  68
  69 Containers use the same kernel as the host, so there is a big attack
  70 surface for malicious users. You should consider this fact if you
  71 provide containers to totally untrusted people. In general, fully
  72 virtualized VM provides better isolation.
  73
  74 The good news is that LXC uses many kernel security features like
  75 AppArmor, CGroups and PID and user namespaces, which makes containers
  76 usage quite secure. We distinguish two types of containers:
  77
  78 Privileged containers
  79 ~~~~~~~~~~~~~~~~~~~~~
  80
  81 Security is done by dropping capabilities, using mandatory access
  82 control (AppArmor), SecComp filters and namespaces. The LXC team
  83 considers this kind of container as unsafe, and they will not consider
  84 new container escape exploits to be security issues worthy of a CVE
  85 and quick fix. So you should use this kind of containers only inside a
  86 trusted environment, or when no untrusted task is running as root in
  87 the container.
  88
  89 Unprivileged containers
  90 ~~~~~~~~~~~~~~~~~~~~~~~
  91
  92 This kind of containers use a new kernel feature, called user
  93 namespaces. The root uid 0 inside the container is mapped to an
  94 unprivileged user outside the container. This means that most security
  95 issues (container escape, resource abuse, ...) in those containers
  96 will affect a random unprivileged user, and so would be a generic
  97 kernel security bug rather than a LXC issue. LXC people think
  98 unprivileged containers are safe by design.
  99
 100
 101 Managing Containers with 'pct'
 102 ------------------------------
 103
 104 'pct' is a tool to manages Linux Containers (LXC). You can create and
 105 destroy containers, and control execution
 106 (start/stop/suspend/resume). Besides that, you can use pct to set
 107 parameters in the associated config file, like network configuration
 108 or memory.
 109
 110 CLI Usage Examples
 111 ------------------
 112
 113 Create a container based on a Debian template (provided you downloaded
 114 the template via the webgui before)
 115
 116  pct create 100 /var/lib/vz/template/cache/debian-8.0-standard_8.0-1_amd64.tar.gz
 117
 118 Start container 100
 119
 120  pct start 100
 121
 122 Start a login session via getty
 123
 124  pct console 100
 125
 126 Enter the LXC namespace and run a shell as root user
 127
 128  pct enter 100
 129
 130 Display the configuration
 131
 132  pct config 100
 133
 134 Add a network interface called eth0, bridged to the host bridge vmbr0,
 135 set the address and gateway, while it's running
 136
 137  pct set 100 -net0 name=eth0,bridge=vmbr0,ip=192.168.15.147/24,gw=192.168.15.1
 138
 139 Reduce the memory of the container to 512MB
 140
 141  pct set -memory 512 100
 142
 143 Files
 144 ------
 145
 146 '/etc/pve/lxc/<vmid>.conf'::
 147
 148 Configuration file for the container <vmid>
 149
 150
 151 Container Advantages
 152 --------------------
 153
 154 - Simple, and fully integrated into {pve}. Setup looks similar to a normal
 155   VM setup.
 156
 157   * Storage (ZFS, LVM, NFS, Ceph, ...)
 158
 159   * Network
 160
 161   * Authentification
 162
 163   * Cluster
 164
 165 - Fast: minimal overhead, as fast as bare metal
 166
 167 - High density (perfect for idle workloads)
 168
 169 - REST API
 170
 171 - Direct hardware access
 172
 173
 174 Technology Overview
 175 -------------------
 176
 177 - Integrated into {pve} graphical user interface (GUI)
 178
 179 - LXC (https://linuxcontainers.org/)
 180
 181 - cgmanager for cgroup management
 182
 183 - lxcfs to provive containerized /proc file system
 184
 185 - apparmor
 186
 187 - CRIU: for live migration (planned)
 188
 189 - We use latest available kernels (4.2.X)
 190
 191 - image based deployment (templates)
 192
 193 - Container setup from host (Network, DNS, Storage, ...)
 194
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