update

mywiki/tiddlers/SSH agent forwarding and screen.tid

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+created: 20150626150315424
+creator: user
+modified: 20150626150415353
+modifier: user
+tags: ssh
+title: SSH agent forwarding and screen
+type: text/x-markdown
+
+SSH agent forwarding and screen
+===============================
+
+When connecting to a remote server via SSH it is often convenient to use SSH agent forwarding so that you don't need a separate keypair on that server for connecting to further servers.
+
+This is enabled by adding the
+
+    ForwardAgent yes
+
+option to any of your `Host` entries in `~/.ssh/config` (or alternatively with the `-A` option). Don't set this option in a wildcard `Host *` section since any user on the remote server that can bypass file permissions can now als use keys loaded in your SSH agent. So only use this with hosts you trust.
+
+
+The problem with screen
+-----------------------
+
+Unfortunately, this doesn't work as-is with GNU screen. On every new SSH connection, agent forwarding is setup via a socket specified in the `SSH_AUTH_SOCK` environment variable (usually somewhere in `/tmp`). So the socket location will be different on each connection. However, your typical screen session will live over several SSH connections and the shells in your screen session won't know where to find the current socket (their environments are not updated).
+
+
+Fixing agent forwarding with screen
+-----------------------------------
+
+A simple fix is to symlink to the current socket from a fixed location on each new connection and have SSH look for the socket in that fixed location (specified by the `SSH_AUTH_SOCK` environment variable). We'll use `~/.ssh/ssh_auth_sock` for the symlink location.
+
+To have SSH within a screen session use the symlink, add the following line to `~/.screenrc`:
+
+    setenv SSH_AUTH_SOCK $HOME/.ssh/ssh_auth_sock
+
+To update the symlink we'll use the `~/.ssh/rc` file which is executed by SSH on each connection. This can be any executable file, so something like the following script will do:
+
+    if test "$SSH_AUTH_SOCK" ; then
+        ln -sf $SSH_AUTH_SOCK ~/.ssh/ssh_auth_sock
+    fi
+
+Unfortunately, this will break X11 forwarding because SSH runs `xauth` on each connection, except when there is a `~/.ssh/rc` file. We can fix this by running `xauth` from our `~/.ssh/rc` as suggested in the `sshd(8)` manual page.
+
+This is our complete `~/.ssh/rc` file:
+
+    #!/bin/bash
+
+    # Fix SSH auth socket location so agent forwarding works with screen.
+    if test "$SSH_AUTH_SOCK" ; then
+        ln -sf $SSH_AUTH_SOCK ~/.ssh/ssh_auth_sock
+    fi
+
+    # Taken from the sshd(8) manpage.
+    if read proto cookie && [ -n "$DISPLAY" ]; then
+            if [ `echo $DISPLAY | cut -c1-10` = 'localhost:' ]; then
+                    # X11UseLocalhost=yes
+                    echo add unix:`echo $DISPLAY |
+                        cut -c11-` $proto $cookie
+            else
+                    # X11UseLocalhost=no
+                    echo add $DISPLAY $proto $cookie
+            fi | xauth -q -
+    fi
+
+Credits go to this blog post: [Managing SSH Sockets in GNU Screen](http://techblog.appnexus.com/2011/managing-ssh-sockets-in-gnu-screen/)

mywiki/tiddlers/docker-compose.tid

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+created: 20150706134157211
+creator: user
+modified: 20150706134701187
+modifier: user
+tags: docker
+title: docker-compose
+type: text/vnd.tiddlywiki
+
+http://stackoverflow.com/questions/29289785/how-to-install-docker-compose-on-windows
+
+To install docker-compose from PyPI, run this from inside boot2docker:
+
+```bash
+docker@boot2docker:~$ 
+tce-load -wi python && curl https://bootstrap.pypa.io/get-pip.py | \
+  sudo python - && sudo pip install -U docker-compose
+```
+
+To save having to run the above every time the boot2docker VM is restarted (since changes don't persist), you can use `bootlocal.sh` like so:
+
+```bash
+docker@boot2docker:~$ 
+echo 'su docker -c "tce-load -wi python" && \
+  curl https://bootstrap.pypa.io/get-pip.py | \
+  python - && pip install -U docker-compose' | \ 
+  sudo tee /var/lib/boot2docker/bootlocal.sh > /dev/null && \
+  sudo chmod +x /var/lib/boot2docker/bootlocal.sh
+```
+
+(The `su docker -c` gymnastics are required since `tce-load` cannot be run as root, and `bootlocal.sh` is run as root. The `chmod` of `bootlocal.sh` should be unnecessary once #915 is fixed.
+Add -a to the `tee` command if you need to append, rather than overwrite `bootlocal.sh`.)
+
+If you wish to use a pre-release version of docker-compose, then replace `pip install -U docker-compose` with `pip install -U docker-compose>=1.3.0rc1` or equivalent.