[proxy] use logs for getting proxy-env and proxy-config

It's ugly, but beats arg-parsing, inspecting the container and piecing
the address together from exposed ports.

We could just use the host from DOCKER_HOST, but that will fail in the
case of a host with multiple IPs, where the proxy only listens on one.

proxy/proxy.go

@@ -108,7 +108,7 @@ func (proxy *Proxy) ListenAndServe() error {
 		listener = tls.NewListener(listener, proxy.TLSConfig.Config)
 	}
 
-	Info.Println("proxy listening")
+	Info.Println("proxy listening on", proxy.ListenAddr)
 
 	return (&http.Server{Handler: proxy}).Serve(listener)
 }

site/proxy.md

@@ -40,13 +40,18 @@ interfaces. This can be adjusted with the `-H` argument, e.g.
 
     host1$ weave launch-proxy -H tcp://127.0.0.1:9999
 
-All docker commands can be run via the proxy, so it is safe to
-globally adjust your `DOCKER_HOST` to point at the proxy, e.g.
+All docker commands can be run via the proxy, so it is safe to adjust
+your `DOCKER_HOST` to point at the proxy. Weave provides a convenient
+command for this:
 
-    host1$ export DOCKER_HOST=tcp://localhost:12375
+    host1$ eval "$(weave proxy-env)"
     host1$ docker ps
     ...
 
+Alternatively, the proxy host can be set on a per-command basis with
+
+    host1$ docker $(weave proxy-config) ps
+
 If you are working with a remote docker daemon, then `localhost` in
 the above needs to be replaced with the docker daemon host, and any
 firewalls inbetween need to be configured to permit access to
@@ -137,12 +142,12 @@ to point at the latter:
     host1$ weave launch -iprange 10.2.3.0/24
     host1$ weave launch-dns 10.2.4.1/24
     host1$ weave launch-proxy --with-ipam --with-dns
-    host1$ export DOCKER_HOST=tcp://localhost:12375
+    host1$ eval "$(weave proxy-env)"
 
     host2$ weave launch -iprange 10.2.3.0/24 host1
     host2$ weave launch-dns 10.2.4.2/24
     host2$ weave launch-proxy --with-ipam --with-dns
-    host2$ export DOCKER_HOST=tcp://localhost:12375
+    host1$ eval "$(weave proxy-env)"
 
 NB: Note that the two weaveDNS instances must be given unique IPs, on
 a subnet different from that used for IP allocation.
@@ -195,7 +200,8 @@ with
 
     $ mkdir -pv ~/.docker
     $ cp -v {ca,cert,key}.pem ~/.docker
-    $ export DOCKER_HOST=tcp://host1:12375 DOCKER_TLS_VERIFY=1
+    $ eval "$(weave proxy-env)"
+    $ export DOCKER_TLS_VERIFY=1
     $ docker version
     ...
 

test/650_proxy_env_test.sh

@@ -0,0 +1,13 @@
+#! /bin/bash
+
+. ./config.sh
+
+start_suite "Configure the docker daemon for the proxy"
+
+weave_on $HOST1 launch-proxy
+
+CMD="run -e WEAVE_CIDR=10.2.1.4/24 $BASE_IMAGE $CHECK_ETHWE_UP"
+assert_raises "eval '$(weave_on $HOST1 proxy-env)' ; docker $CMD"
+assert_raises "docker $(weave_on $HOST1 proxy-config) $CMD"
+
+end_suite

weave

@@ -16,6 +16,8 @@ IMAGE_VERSION=${VERSION:-$IMAGE_VERSION}
 DOCKERHUB_USER=weaveworks
 BASE_EXEC_IMAGE=$DOCKERHUB_USER/weaveexec
 EXEC_IMAGE=$BASE_EXEC_IMAGE:$IMAGE_VERSION
+PROXY_HOST=${PROXY_HOST:-$(echo "${DOCKER_HOST#tcp://}" | cut -s -d: -f1)}
+PROXY_HOST=${PROXY_HOST:-127.0.0.1}
 
 # Define some regular expressions for matching addresses.
 # The regexp here is far from precise, but good enough.
@@ -41,6 +43,8 @@ usage() {
     echo "weave hide         [<cidr> ...]"
     echo "weave ps           [<container_id> ...]"
     echo "weave status"
+    echo "weave proxy-env"
+    echo "weave proxy-config"
     echo "weave version"
     echo "weave stop"
     echo "weave stop-dns"
@@ -69,6 +73,7 @@ exec_remote() {
         -e WEAVE_PORT \
         -e WEAVE_CONTAINER_NAME \
         -e DOCKER_BRIDGE \
+        -e PROXY_HOST="$PROXY_HOST" \
         $WEAVEEXEC_DOCKER_ARGS $EXEC_IMAGE --local "$@"
 }
 
@@ -171,6 +176,7 @@ MTU=65535
 PORT=${WEAVE_PORT:-6783}
 HTTP_PORT=6784
 DNS_HTTP_PORT=6785
+PROXY_PORT=12375
 PROXY_CONTAINER_NAME=weaveproxy
 
 
@@ -805,6 +811,19 @@ proxy_args() {
     done
 }
 
+proxy_addr() {
+    if addr=$(docker logs weaveproxy | head -n3 | grep -oE "proxy listening on .*"); then
+      addr=${addr##* }
+      host=${addr%:*}
+      [ "$host" = "0.0.0.0" ] && host=$PROXY_HOST
+      port=${addr#*:}
+      echo "${1}tcp://${host:-$PROXY_HOST}:${port:-$PROXY_PORT}"
+      return 0
+    fi
+    echo  "$PROXY_CONTAINER_NAME container is not present. Have you launched it?" >&2
+    return 1
+}
+
 ##########################################################################################
 
 [ $(id -u) = 0 ] || {
@@ -953,6 +972,12 @@ case "$COMMAND" in
         wait_for_log $PROXY_CONTAINER_NAME "proxy listening"
         echo $PROXY_CONTAINER
         ;;
+    proxy-env)
+        proxy_addr "export DOCKER_HOST="
+        ;;
+    proxy-config)
+        proxy_addr "-H="
+        ;;
     connect)
         [ $# -gt 0 ] || usage
         if [ "$1" == "--replace" ]; then