Matthias Radestock
56c720b078
It doesn't do anything useful since the weave script needs to be able to talk to docker on the standard unix socket. Also remove dangling reference to 'localhost', and move note about firwalls to where it is most pertinent. Part fix to #972.
232 lines
7.8 KiB
Markdown
232 lines
7.8 KiB
Markdown
---
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title: Weave Proxy
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layout: default
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---
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# Weave Proxy
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The proxy automatically attaches containers to the weave network when
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they are started using the ordinary Docker
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[command-line interface](https://docs.docker.com/reference/commandline/cli/)
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or
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[remote API](https://docs.docker.com/reference/api/docker_remote_api/),
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instead of `weave run`.
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* [Setup](#setup)
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* [Usage](#usage)
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* [Automatic IP address assignment](#ipam)
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* [Automatic discovery](#dns)
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* [Multi-host example](#multi-host)
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* [Securing the docker communication with TLS](#tls)
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* [Troubleshooting](#troubleshooting)
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## <a name="setup"></a>Setup
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The proxy sits between the Docker client (command line or API) and the
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Docker daemon, intercepting the communication between the two.
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To start the proxy, run
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host1$ weave launch-proxy
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By default, the proxy listens on port 12375, on all network
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interfaces. This can be adjusted with the `-H` argument, e.g.
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host1$ weave launch-proxy -H tcp://127.0.0.1:9999
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If you are working with a remote docker daemon, then any firewalls
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inbetween need to be configured to permit access to the proxy port.
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All docker commands can be run via the proxy, so it is safe to adjust
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your `DOCKER_HOST` to point at the proxy. Weave provides a convenient
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command for this:
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host1$ eval "$(weave proxy-env)"
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host1$ docker ps
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...
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Alternatively, the proxy host can be set on a per-command basis with
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host1$ docker $(weave proxy-config) ps
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The proxy can be stopped with
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host1$ weave stop-proxy
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If you set your `DOCKER_HOST` to point at the proxy, remember to
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revert to the original setting.
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## <a name="usage"></a>Usage
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When containers are created via the weave proxy, their entrypoint will
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be modified to wait for the weave network interface to become
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available. When they are started via the weave proxy, containers will
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be [automatically assigned IP addresses](#ipam) and connected to the
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weave network. We can create and start a container via the weave proxy
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with
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host1$ docker run -ti ubuntu
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or, equivalently with
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host1$ docker create -ti ubuntu
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5ef831df61d50a1a49272357155a976595e7268e590f0a2c75693337b14e1382
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host1$ docker start 5ef831df61d50a1a49272357155a976595e7268e590f0a2c75693337b14e1382
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Specific IP addresses and networks can be supplied in the `WEAVE_CIDR`
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environment variable, e.g.
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host1$ docker run -e WEAVE_CIDR=10.2.1.1/24 -ti ubuntu
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Multiple IP addresses and networks can be supplied in the `WEAVE_CIDR`
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variable by space-separating them, as in
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`WEAVE_CIDR="10.2.1.1/24 10.2.2.1/24"`.
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Using the proxy brings some additional benefits over `weave run`. The
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proxy ensures that the weave network interface is available before
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starting a container's application process. Furthermore, containers
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can be started in foreground mode, and can be automatically removed
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(with the ususal `--rm`).
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## <a name="ipam"></a>Automatic IP address assignment
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If [automatic IP address assignment](ipam.html) is enabled in weave,
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which it is by default, then containers started via the proxy will be
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automatically assigned an IP address, *without having to specify any
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special environment variables or other options*.
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host1$ docker run -ti ubuntu
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To use a specific IP, we pass a `WEAVE_CIDR` to the container, e.g.
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host1$ docker run -ti -e WEAVE_CIDR=10.2.1.1/24 ubuntu
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To start a container without connecting it to the weave network, pass
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`WEAVE_CIDR=none`, e.g.
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host1$ docker run -ti -e WEAVE_CIDR=none ubuntu
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If you do not want IPAM to be used by default, the proxy needs to be
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passed the `--no-default-ipam` flag, e.g.
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host1$ docker launch-proxy --no-default-ipam
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In this configuration, containers with no `WEAVE_CIDR` environment
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variable will not be connected to the weave network. Containers
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started with a `WEAVE_CIDR` environment variable are handled as
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before. To automatically assign an address in this mode, we start the
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container with a blank `WEAVE_CIDR`, e.g.
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host1$ docker run -ti -e WEAVE_CIDR= ubuntu
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## <a name="dns"></a>Automatic discovery
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Containers started via the proxy are automatically registered in
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[weaveDNS](weavedns.html) if they have a hostname in the weaveDNS
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domain (usually `.weave.local`). In order for containers to be able to
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look up such names, their DNS resolver needs to be configured to point
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at weaveDNS. This will be done automatically by the proxy while
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weaveDNS is running. To override this behaviour launch the proxy with
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either `--with-dns` or `--without-dns`, which will force the proxy to
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always/never set the resolver to weaveDNS. If there is no hostname
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provided, the container will be registered in weaveDNS using its
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container name. Otherwise, if there is no container name, and no
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hostname (or a hostname outside the weaveDNS domain), the container
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will not be registered in weaveDNS.
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## <a name="multi-host"></a>Multi-host example
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Here's a complete example of using weave proxies configured with
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[automatic IP address assignment](#ipam) and
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[automatic discovery](#dns) to start containers on two hosts such that
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one can reach the other by name.
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First, let us start weave, weaveDNS and the proxy, and set DOCKER_HOST
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to point at the latter:
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host1$ weave launch
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host1$ weave launch-dns
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host1$ weave launch-proxy
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host1$ eval "$(weave proxy-env)"
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host2$ weave launch host1
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host2$ weave launch-dns
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host2$ weave launch-proxy
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host2$ eval "$(weave proxy-env)"
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Now let us start a named container on one host, and ping it, by name,
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from a container on the other host.
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host1$ docker run --name=pingme -dti ubuntu
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host2$ docker run -ti ubuntu ping pingme
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PING pingme.weave.local (10.128.0.2) 56(84) bytes of data.
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64 bytes from pingme.weave.local (10.128.0.2): icmp_seq=1 ttl=64 time=0.047 ms
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...
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## <a name="tls"></a>Securing the docker communication with TLS
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If you are
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[connecting to the docker daemon with TLS](https://docs.docker.com/articles/https/),
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you will probably want to do the same when connecting to the
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proxy. That is accomplished by launching the proxy with the same
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TLS-related command-line flags as supplied to the docker daemon. For
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example, if you have generated your certificates and keys into the
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docker host's `/tls` directory, we can launch the proxy with:
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host1$ weave launch-proxy --tlsverify --tlscacert=/tls/ca.pem \
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--tlscert=/tls/server-cert.pem --tlskey=/tls/server-key.pem
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The paths to your certificates and key must be provided as absolute
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paths which exist on the docker host.
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Because the proxy connects to the docker daemon at
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`unix:///var/run/docker.sock`, you must ensure that the daemon is
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listening there. To do this, you need to pass the `-H
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unix:///var/run/docker.sock` option when starting the docker daemon,
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in addition to the `-H` options for configuring the TCP listener. See
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[the Docker documentation](https://docs.docker.com/articles/basics/#bind-docker-to-another-hostport-or-a-unix-socket)
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for an example.
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With the proxy running over TLS, we can configure our regular docker
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client to use TLS on a per-invocation basis with
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$ docker --tlsverify --tlscacert=ca.pem --tlscert=cert.pem \
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--tlskey=key.pem -H=tcp://host1:12375 version
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...
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or,
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[by default](https://docs.docker.com/articles/https/#secure-by-default),
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with
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$ mkdir -pv ~/.docker
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$ cp -v {ca,cert,key}.pem ~/.docker
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$ eval "$(weave proxy-env)"
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$ export DOCKER_TLS_VERIFY=1
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$ docker version
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...
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which is exactly the same configuration as when connecting to the
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docker daemon directly, except that the specified port is the weave
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proxy port.
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## <a name="troubleshooting"></a>Troubleshooting
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The command
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weave status
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reports on the current status of various weave components, including
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the proxy, if it is running:
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````
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...
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weave proxy is running
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````
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Information on the operation of the proxy can be obtained from the
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weaveproxy container logs with
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docker logs weaveproxy
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