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<h1>About</h1>
<p>
Converge is a utility for troubleshooting builds on continuous integration servers.
It solves a common problem where the cause of job failure is difficult to determine.
This is complicated further by the fact that build jobs are usually run on a build
farm where there is no access to the build agents or in more modern envrionments when
jobs are run in ephemeral containers.
</p>
<p>
With Converge it is possible to get remote shell access to such jobs. This works
by configuring the build job to connect to a Converge server using an agent program.
The agent program can be downloaded from within the CI job using curl or wget.
Next, an end-user can connect to the Converge server, a rendez-vous server, that connects
the client and server together.
</p>
<p>
The setup is such that the connection from client (end-user) to server (agent on CI job)
is end-to-end encrypted. The Converge server itself is no more than a bitpipe which pumps
data between client and agent.
</p>
<p>
Both ssh and sftp are supported. Multiple shells are also allowed.
</p>
<p>
There is a timeout mechanism in the agent such that jobs do not hang indefinitely waiting
for a connection. This mechanism is useful to make sure build agents do not keep
build agents occupied for a long time. By default, the agent exits with status 0 when
the first client exits after logging in. This behavior as well as general expiry can be
controlled from within a shell session by touching a .hold file. After logging in, the
user can control expiry of the session as instructed by messages in the ssh session.
When the timeout of a session is near the user is informed about this with messages
in the shell.
</p>
<h1>Usage</h1>
<h2>Continous integration jobs</h2>
<p>
In a continous integration job, download the agent, chmod it and run it.
</p>
<pre>
curl http@secure@://@host@/docs/agent > agent
chmod 755 agent
./agent ws@secure@://@host@/agent/ID
</pre>
<p>
Above, ID is a unique id
for the job. This should not conflict with other ids.
This connects the agent to the converge server. Clients can now connect to the Converge
server to establish a connection to the CI job through converge.
</p>
<h2>Local clients: using ssh proxy command </h2>
<pre>
curl http@secure@://@host@/docs/wsproxy > wsproxy
chmod 755 wsproxy
</pre>
<p>This is a command that can be used as a proxy command for SSH which performs the connection to the remote
server.</p>
<p>
Next step is to run a local SSH or SFTP client:
</p>
<pre>
ssh -oServerAliveInterval=10 -oProxyCommand="wsproxy ws@secure@://@host@/client/ID" abc@localhost
sftp -oServerAliveInterval=10 -oProxyCommand="wsproxy ws@secure@://@host@/client/ID" abc@localhost
</pre>
<p>
<code>abc</code> is a fixed user defined by converge. It has a very exciting password.
</p>
<h2>Local clients: with a local TCP forwarding proxy</h2>
This option is less convenient than the proxy command because it requires two separate
commands to execute.
<p>
Local clients can connect using regular ssh and sftp commands through a tunnel that
translates a local TCP port to a websocket connection in converge.
First step is to download the tcptows program (see below):
</p>
<pre>
curl http@secure@://@host@/docs/tcptows > tcptows
chmod 755 tcptows
./tcptows 10000 ws@secure@://@host@/client/ID
</pre>
<p>
This runs a local client that allows SSH to port 10000 and connects to converge using
a websocket connection.</p>
<p>
Next step is to run a local SSH of SFTP client:
</p>
<pre>
ssh -oServerAliveInterval=10 -p 10000 abc@localhost
sftp -oServerAliveInterval=10 -oPort=10000 abc@localhost
</pre>
<p>
<code>abc</code> is a fixed user defined by converge. It has a very exciting password.
</p>
<h1>Downloads</h1>
<ul>
<li><a href="/docs/agent">agent</a>: The agent to run inside aa CI job
</li>
<li><a href="/docs/tcptows">tcptows</a>: TCP to WS tunnel for allowing regular
SSH and SFTP clients to connect to converge.
</li>
<li><a href="/docs/wsproxy">wsproxy</a>: SSH proxy command that can be directly used by ssh
</li>
</ul>
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