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Add clarification on install for VM cloning and Engine ID duplication issue #1472
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ping @moxiegirl |
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I agree about needing the warning. I know and understand what the issue is, so it reads okay to me. I would like someone who doesn't know about the issue to understand what the text is talking about. |
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LGTM. Thanks @abronan. |
| @@ -27,7 +27,7 @@ You can run Docker Swarm on Linux 64-bit architectures. You can also install and | |||
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| Take a moment and identify the systems on your network that you intend to use. Ensure each node meets the requirements listed above. | |||
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| > **Warning**: Before going any further with the setup process, make sure that Docker is not pre-installed on your VM image and/or that the machine is not created using VM cloning. Docker generates a unique ID for the Engine that is located in the `/etc/docker/key.json` file. If a VM is the result of cloning with a docker daemon pre-installed, Swarm will not be able to recognize remote docker Engines as different. This is because the same unique ID is duplicated on those Engines from the VM cloning. As a result, you will see a single docker Engine registered on Swarm. As a workaround you can stop the daemon on those machines, delete the `/etc/docker/key.json` and finally restart the Engines. This will regenerate a new ID for each of those docker daemons. | |||
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@MHBauer I don't actually know this particular issue. Tho, I am close to the issue:
- VM cloning --- how would a user go about that --- it would be helpful to explain it. Clone an image with AWS or something different?
- Does a user see a warning / error message during the setup about this? Presenting that message will help them to debug the problem.
Also, this Warning really is too long to be a warning. So, I'd likely to restructure once I know the answer to the questions...or I may find the time to setup and test it myself.
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@moxiegirl Yeah I admit I went a little too overboard with that warning 😅
Will try to re-structure and make it more clear and concise.
| @@ -27,7 +27,7 @@ You can run Docker Swarm on Linux 64-bit architectures. You can also install and | |||
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| Take a moment and identify the systems on your network that you intend to use. Ensure each node meets the requirements listed above. | |||
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@abronan try this
## Prerequisites
You install Docker Swarm on a single system which is known as your Docker Swarm
manager. You create the cluster, or swarm, on one or more additional nodes on
your network. Each node in your swarm must:
* be accessible by the swarm manager across your network
* have Docker Engine 1.6.0+ installed
* open a TCP port to listen for the manager
* *do not* install on VM or other image created through cloning
Docker generates a unique ID for the Engine that is located in the
`/etc/docker/key.json` file. If a VM is cloned from an instance where the a
Docker daemon was previously pre-installed, Swarm is unable to differentiate
among the remote Docker engines. This is because the cloning process copied the
the identical ID to each image and the ID is no longer unique.
If you forget this restriction and create a node anyway, Swarm displays a single
Docker engine as registered. To workaround this problem, by regenerating a new
ID for each node with the problem. To do this stop the daemon on a node, delete
its `/etc/docker/key.json` file, and restart the daemon.
You can run Docker Swarm on Linux 64-bit architectures. You can also install and
run it on 64-bit Windows and Max OSX but these architectures are *not* regularly
tested for compatibility.
Take a moment and identify the systems on your network that you intend to use.
Ensure each node meets the requirements listed above.
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@moxiegirl PTAL. Thanks for the suggestions, much much better now 😄 |
| You can run Docker Swarm on Linux 64-bit architectures. You can also install and run it on 64-bit Windows and Max OSX but these architectures are *not* regularly tested for compatibility. | ||
| Docker generates a unique ID for the Engine that is located in the | ||
| `/etc/docker/key.json` file. If a VM is cloned from an instance where a | ||
| Docker daemon was previously pre-installed, Swarm will unable to differentiate |
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@abronan Glad I could help. I spotted one minor problem but otherwise LGTM. After that fix, merge away. |
… problem Signed-off-by: Alexandre Beslic <abronan@docker.com>
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Add clarification on install for VM cloning and Engine ID duplication issue
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…icate_engine_ids Add clarification on install for VM cloning and Engine ID duplication issue
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Fix #1467
Signed-off-by: Alexandre Beslic abronan@docker.com