17668: basic documentation for the new container shell feature.

Arvados-DCO-1.1-Signed-off-by: Ward Vandewege <ward@curii.com>

diff --git a/doc/_config.yml b/doc/_config.yml
index d6f91b36c1311830077eec30e476704d324f0d67..3974745aa716eb766a46ecca0f15dcc7bb1ba6bc 100644 (file)
--- a/doc/_config.yml
+++ b/doc/_config.yml
@@ -58,6 +58,7 @@ navbar:
       - user/cwl/federated-workflows.html.textile.liquid
       - user/cwl/cwl-versions.html.textile.liquid
       - user/cwl/crunchstat-summary.html.textile.liquid
+      - user/debugging/container-shell-access.html.textile.liquid
     - Working with git repositories:
       - user/tutorials/add-new-repository.html.textile.liquid
       - user/tutorials/git-arvados-guide.html.textile.liquid
@@ -251,6 +252,8 @@ navbar:
       - install/crunch2-slurm/configure-slurm.html.textile.liquid
       - install/crunch2-slurm/install-compute-node.html.textile.liquid
       - install/crunch2-slurm/install-test.html.textile.liquid
+    - Additional configuration:
+      - install/container-shell-access.html.textile.liquid
     - External dependencies:
       - install/install-postgresql.html.textile.liquid
       - install/ruby.html.textile.liquid

diff --git a/doc/install/container-shell-access.html.textile.liquid b/doc/install/container-shell-access.html.textile.liquid
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@@ -0,0 +1,44 @@
+---
+layout: default
+navsection: installguide
+title: Configure container shell access
+...
+{% comment %}
+Copyright (C) The Arvados Authors. All rights reserved.
+
+SPDX-License-Identifier: CC-BY-SA-3.0
+{% endcomment %}
+
+Arvados can be configured to permit shell access to running containers. This can be handy for debugging, but it could affect reproducability of workflows. This feature can be enabled for admin users, or for all users. By default, it is entirely disabled.
+
+The relevant configuration section is
+
+<notextile>
+<pre><code>    Containers:
+      ShellAccess:
+        # An admin user can use "arvados-client shell" to start an
+        # interactive shell (with any user ID) in any running
+        # container.
+        Admin: false
+
+        # Any user can use "arvados-client shell" to start an
+        # interactive shell (with any user ID) in any running
+        # container that they started, provided it isn't also
+        # associated with a different user's container request.
+        #
+        # Interactive sessions make it easy to alter the container's
+        # runtime environment in ways that aren't recorded or
+        # reproducible. Consider the implications for automatic
+        # container reuse before enabling and using this feature. In
+        # particular, note that starting an interactive session does
+        # not disqualify a container from being reused by a different
+        # user/workflow in the future.
+        User: false
+</code></pre>
+</notextile>
+
+To enable the feature a firewall change may also be required. Traffic from the machine that runs @arvados-controller@ to the compute nodes in the port range above 1024 must be allowed.
+
+After changing the configuration, @arvados-controller@ must be restarted for the change to take effect. When enabling, the change will only affect containers started from that point on. When disabling, access is removed immediately for any running containers, as well as any containers started subsequently.
+
+Usage instructions for this feature are available in the "User guide":{{site.baseurl}}/user/debugging/container-shell-access.html.

diff --git a/doc/user/debugging/container-shell-access.html.textile.liquid b/doc/user/debugging/container-shell-access.html.textile.liquid
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+++ b/doc/user/debugging/container-shell-access.html.textile.liquid
@@ -0,0 +1,78 @@
+---
+layout: default
+navsection: userguide
+title: Debugging workflows - shell access
+...
+{% comment %}
+Copyright (C) The Arvados Authors. All rights reserved.
+
+SPDX-License-Identifier: CC-BY-SA-3.0
+{% endcomment %}
+
+{% include 'notebox_begin' %}
+
+To use this feature, your Arvados installation must be configured to allow container shell access. See "the install guide":{{site.baseurl}}/install/container-shell-access.html for more information.
+
+{% include 'notebox_end' %}
+
+The @arvados-client@ program can be used to connect to a container in a running workflow. It can be installed from packages (@apt install arvados-client@ or @yum install arvados-client@). The @arvados-client shell@ command provides an ssh connection into a running container.
+
+h2(#syntax). Syntax
+
+The @arvados-client shell@ tool has a number of command line arguments:
+
+<notextile>
+<pre><code>~$ <span class="userinput">arvados-client shell -h</span>
+arvados-client shell: open an interactive shell on a running container.
+
+Usage: arvados-client shell [options] [username@]container-uuid [ssh-options] [remote-command [args...]]
+
+Options:
+  -detach-keys string
+      set detach key sequence, as in docker-attach(1) (default "ctrl-],ctrl-]")
+
+</code></pre>
+</notextile>
+
+h2(#Examples). Examples
+
+Connect to a running container, using the container request UUID:
+
+<notextile>
+<pre><code>~$ <span class="userinput">./arvados-client shell ce8i5-xvhdp-e6wnujfslyyqn4b</span>
+root@0f13dcd755fa:~#
+</code></pre>
+</notextile>
+
+The container UUID also works:
+
+<notextile>
+<pre><code>~$ <span class="userinput">./arvados-client shell ce8i5-dz642-h1cl0sa62d4i430</span>
+root@0f13dcd755fa:~#
+</code></pre>
+</notextile>
+
+SSH port forwarding is supported:
+
+<notextile>
+<pre><code>~$ <span class="userinput">./arvados-client shell ce8i5-dz642-h1cl0sa62d4i430 -L8888:localhost:80</span>
+root@0f13dcd755fa:~# nc -l -p 80
+</code></pre>
+</notextile>
+
+And then, connecting to port 8888 locally:
+
+<notextile>
+<pre><code>~$ <span class="userinput">nc localhost 8888</span>
+hello
+</code></pre>
+</notextile>
+
+Which appears on the other end:
+
+<notextile>
+<pre><code>~$ <span class="userinput">./arvados-client shell ce8i5-dz642-h1cl0sa62d4i430 -L8888:localhost:80</span>
+root@0f13dcd755fa:~# nc -l -p 80
+hello
+</code></pre>
+</notextile>