mirror of https://github.com/docker/docs.git
Merge pull request #8043 from docker/deprecated-page
remove outdated ambassador pattern #7845
This commit is contained in:
L-Hudson
GitHub
commit
6b63320457
|
|
@ -1,179 +0,0 @@
|
||||||
---
|
|
||||||
description: Using the Ambassador pattern to abstract (network) services
|
|
||||||
keywords: Examples, Usage, links, docker, documentation, examples, names, name, container naming
|
|
||||||
redirect_from:
|
|
||||||
- /engine/articles/ambassador_pattern_linking/
|
|
||||||
- /engine/admin/ambassador_pattern_linking/
|
|
||||||
title: (Obsolete) Link via an ambassador container
|
|
||||||
noratings: true
|
|
||||||
---
|
|
||||||
|
|
||||||
This content is out of date. Docker now includes better ways to
|
|
||||||
manage multiple services together, as well as a mix of containerized and
|
|
||||||
uncontainerized services. Consider using one or more of the following:
|
|
||||||
|
|
||||||
- [User-defined networks](/engine/userguide/networking.md#user-defined-networks)
|
|
||||||
allow you to connect services together, including managing DNS resolution
|
|
||||||
among them.
|
|
||||||
|
|
||||||
- [Overlay networks](/engine/userguide/networking/overlay-security-model.md)
|
|
||||||
allow containers running on different Docker hosts to communicate in a
|
|
||||||
seamless, encapsulated way.
|
|
||||||
|
|
||||||
- [Configs](/engine/swarm/configs.md) allow you to plug configuration details
|
|
||||||
into swarm service containers at runtime instead of baking configuration
|
|
||||||
details into your Docker images. This allows you to change configuration
|
|
||||||
details, such as IP addresses to reach services external to Docker, on the fly.
|
|
||||||
|
|
||||||
- [Stacks](https://docs.docker.com/get-started/part5/) allow you to group
|
|
||||||
multiple swarm services together, including defining networks, storage, and
|
|
||||||
dependency relationships among the services.
|
|
||||||
|
|
||||||
Consider using one or more of the above solutions rather than the content below.
|
|
||||||
|
|
||||||
## Obsolete: Ambassador linking model
|
|
||||||
|
|
||||||
Rather than hardcoding network links between a service consumer and
|
|
||||||
provider, Docker encourages service portability, for example instead of:
|
|
||||||
|
|
||||||
(consumer) --> (redis)
|
|
||||||
|
|
||||||
Requiring you to restart the `consumer` to attach it to a different
|
|
||||||
`redis` service, you can add ambassadors:
|
|
||||||
|
|
||||||
(consumer) --> (redis-ambassador) --> (redis)
|
|
||||||
|
|
||||||
Or
|
|
||||||
|
|
||||||
(consumer) --> (redis-ambassador) ---network---> (redis-ambassador) --> (redis)
|
|
||||||
|
|
||||||
When you need to rewire your consumer to talk to a different Redis
|
|
||||||
server, you can just restart the `redis-ambassador` container that the
|
|
||||||
consumer is connected to.
|
|
||||||
|
|
||||||
This pattern also allows you to transparently move the Redis server to a
|
|
||||||
different docker host from the consumer.
|
|
||||||
|
|
||||||
Using the `svendowideit/ambassador` container, the link wiring is
|
|
||||||
controlled entirely from the `docker run` parameters.
|
|
||||||
|
|
||||||
### Two host example
|
|
||||||
|
|
||||||
Start actual Redis server on one Docker host
|
|
||||||
|
|
||||||
big-server $ docker run -d --name redis crosbymichael/redis
|
|
||||||
|
|
||||||
Then add an ambassador linked to the Redis server, mapping a port to the
|
|
||||||
outside world
|
|
||||||
|
|
||||||
big-server $ docker run -d --link redis:redis --name redis_ambassador -p 6379:6379 svendowideit/ambassador
|
|
||||||
|
|
||||||
On the other host, you can set up another ambassador setting environment
|
|
||||||
variables for each remote port we want to proxy to the `big-server`
|
|
||||||
|
|
||||||
client-server $ docker run -d --name redis_ambassador --expose 6379 -e REDIS_PORT_6379_TCP=tcp://192.168.1.52:6379 svendowideit/ambassador
|
|
||||||
|
|
||||||
Then on the `client-server` host, you can use a Redis client container
|
|
||||||
to talk to the remote Redis server, just by linking to the local Redis
|
|
||||||
ambassador.
|
|
||||||
|
|
||||||
client-server $ docker run -i -t --rm --link redis_ambassador:redis relateiq/redis-cli
|
|
||||||
redis 172.17.0.160:6379> ping
|
|
||||||
PONG
|
|
||||||
|
|
||||||
### How it works
|
|
||||||
|
|
||||||
The following example shows what the `svendowideit/ambassador` container
|
|
||||||
does automatically (with a tiny amount of `sed`)
|
|
||||||
|
|
||||||
On the Docker host (192.168.1.52) that Redis runs on:
|
|
||||||
|
|
||||||
# start actual redis server
|
|
||||||
$ docker run -d --name redis crosbymichael/redis
|
|
||||||
|
|
||||||
# get a redis-cli image for connection testing
|
|
||||||
$ docker pull relateiq/redis-cli
|
|
||||||
|
|
||||||
# test the redis server by talking to it directly
|
|
||||||
$ docker run -t -i --rm --link redis:redis relateiq/redis-cli
|
|
||||||
redis 172.17.0.136:6379> ping
|
|
||||||
PONG
|
|
||||||
^D
|
|
||||||
|
|
||||||
# add redis ambassador
|
|
||||||
$ docker run -t -i --link redis:redis --name redis_ambassador -p 6379:6379 alpine:3.2 sh
|
|
||||||
|
|
||||||
In the `redis_ambassador` container, you can see the linked Redis
|
|
||||||
containers `env`:
|
|
||||||
|
|
||||||
/ # env
|
|
||||||
REDIS_PORT=tcp://172.17.0.136:6379
|
|
||||||
REDIS_PORT_6379_TCP_ADDR=172.17.0.136
|
|
||||||
REDIS_NAME=/redis_ambassador/redis
|
|
||||||
HOSTNAME=19d7adf4705e
|
|
||||||
SHLVL=1
|
|
||||||
HOME=/root
|
|
||||||
REDIS_PORT_6379_TCP_PORT=6379
|
|
||||||
REDIS_PORT_6379_TCP_PROTO=tcp
|
|
||||||
REDIS_PORT_6379_TCP=tcp://172.17.0.136:6379
|
|
||||||
TERM=xterm
|
|
||||||
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
|
|
||||||
PWD=/
|
|
||||||
/ # exit
|
|
||||||
|
|
||||||
This environment is used by the ambassador `socat` script to expose Redis
|
|
||||||
to the world (via the `-p 6379:6379` port mapping):
|
|
||||||
|
|
||||||
$ docker container rm redis_ambassador
|
|
||||||
$ CMD="apk update && apk add socat && sh"
|
|
||||||
$ docker run -t -i --link redis:redis --name redis_ambassador -p 6379:6379 alpine:3.2 sh -c "$CMD"
|
|
||||||
[...]
|
|
||||||
/ # socat -t 100000000 TCP4-LISTEN:6379,fork,reuseaddr TCP4:172.17.0.136:6379
|
|
||||||
|
|
||||||
Now ping the Redis server via the ambassador:
|
|
||||||
|
|
||||||
Now go to a different server:
|
|
||||||
|
|
||||||
$ CMD="apk update && apk add socat && sh"
|
|
||||||
$ docker run -t -i --expose 6379 --name redis_ambassador alpine:3.2 sh -c "$CMD"
|
|
||||||
[...]
|
|
||||||
/ # socat -t 100000000 TCP4-LISTEN:6379,fork,reuseaddr TCP4:192.168.1.52:6379
|
|
||||||
|
|
||||||
And get the `redis-cli` image so we can talk over the ambassador bridge.
|
|
||||||
|
|
||||||
$ docker pull relateiq/redis-cli
|
|
||||||
$ docker run -i -t --rm --link redis_ambassador:redis relateiq/redis-cli
|
|
||||||
redis 172.17.0.160:6379> ping
|
|
||||||
PONG
|
|
||||||
|
|
||||||
### The svendowideit/ambassador Dockerfile
|
|
||||||
|
|
||||||
The `svendowideit/ambassador` image is based on the `alpine:3.2` image with
|
|
||||||
`socat` installed. When you start the container, it uses a small `sed`
|
|
||||||
script to parse out the (possibly multiple) link environment variables
|
|
||||||
to set up the port forwarding. On the remote host, you need to set the
|
|
||||||
variable using the `-e` command line option.
|
|
||||||
|
|
||||||
--expose 1234 -e REDIS_PORT_1234_TCP=tcp://192.168.1.52:6379
|
|
||||||
|
|
||||||
Will forward the local `1234` port to the remote IP and port, in this
|
|
||||||
case `192.168.1.52:6379`.
|
|
||||||
|
|
||||||
#
|
|
||||||
# do
|
|
||||||
# docker build -t svendowideit/ambassador .
|
|
||||||
# then to run it (on the host that has the real backend on it)
|
|
||||||
# docker run -t -i -link redis:redis -name redis_ambassador -p 6379:6379 svendowideit/ambassador
|
|
||||||
# on the remote host, you can set up another ambassador
|
|
||||||
# docker run -t -i -name redis_ambassador -expose 6379 -e REDIS_PORT_6379_TCP=tcp://192.168.1.52:6379 svendowideit/ambassador sh
|
|
||||||
# you can read more about this process at https://docs.docker.com/articles/ambassador_pattern_linking/
|
|
||||||
|
|
||||||
# use alpine because its a minimal image with a package manager.
|
|
||||||
# prettymuch all that is needed is a container that has a functioning env and socat (or equivalent)
|
|
||||||
FROM alpine:3.2
|
|
||||||
|
|
||||||
RUN apk update && \
|
|
||||||
apk add socat && \
|
|
||||||
rm -r /var/cache/
|
|
||||||
|
|
||||||
CMD env | grep _TCP= | (sed 's/.*_PORT_\([0-9]*\)_TCP=tcp:\/\/\(.*\):\(.*\)/socat -t 100000000 TCP4-LISTEN:\1,fork,reuseaddr TCP4:\2:\3 \&/' && echo wait) | sh
|
|
||||||
Loading…
Reference in New Issue