First, a quick refresh of what Couchbase Sync Gateway actually is.

So here’s a birds-eye-view of the Couchbase Mobile architecture:

Sync Gateway allows Couchbase Lite mobile apps to sync data between each other and the Couchbase Server running on the backend.

This blog post will walk you through how to run Sync Gateway in a Docker container on Google Compute Engine.

Create GCE instance and ssh in

Follow the instructions on Running Docker on Google Compute Engine.

At this point you should be ssh’d into your GCE instance

Create a configuration JSON

Here’s a sample example JSON configuration for Sync Gateway which uses walrus as it’s backing store, rather than Couchbase Server. Later we will swap in Couchbase Server as a backing store.

Run Sync Gateway docker container

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gce:~$ sudo docker run -d -name sg -p 4984:4984 -p 4985:4985 tleyden5iwx/couchbase-sync-gateway sync_gateway "https://gist.githubusercontent.com/tleyden/d97d985eb1e0725e858e/raw"

This will return a container id, eg 8ffb83fd1f.

Check the logs to make sure there are no serious errors in the logs:

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gce:~$ sudo docker logs 8ffb83fd1f

You should see something along the lines of:

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02:23:58.905587 Enabling logging: [REST]
02:23:58.905818 ==== Couchbase Sync Gateway/1.00 (unofficial) ====
02:23:58.905863 Opening db /sync_gateway as bucket "sync_gateway", pool "default", server <walrus:/opt/sync_gateway/data>
02:23:58.905964 Opening Walrus database sync_gateway on <walrus:/opt/sync_gateway/data>
02:23:58.909659 Starting admin server on :4985
02:23:58.913260 Starting server on :4984 ...

Expose API port 4984 via Firewall rule

On your workstation with the gcloud tool installed, run:

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$ gcloud compute firewalls create sg-4984 --allow tcp:4984

Verify that it’s running

Find out external ip address of instance

On your workstation with the gcloud tool installed, run:

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$ gcloud compute instances list
name     status  zone          machineType internalIP   externalIP
couchbse RUNNING us-central1-a f1-micro    10.240.74.44 142.222.178.49

Your external ip is listed under the externalIP column, eg 142.222.178.49 in this example.

Run curl request

On your workstation, replace the ip below with your own ip, and run:

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$ curl http://142.222.178.49:4984

You should get a response like:

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{"couchdb":"Welcome","vendor":{"name":"Couchbase Sync Gateway","version":1},"version":"Couchbase Sync Gateway/1.00 (unofficial)"}

Re-run it with Couchbase Server backing store

OK, so we’ve gotten it working with walrus. But have you looked at the walrus website lately? One click and it’s pretty obvious that this thing is not exactly meant to be a scalable production ready backend, nor has it ever claimed to be.

Let’s dump walrus for now and use Couchbase Server from this point onwards.

Start Couchbase Server

Before moving on, you will need to go through the instructions in Running Couchbase Server on GCE in order to get a Couchbase Server instance running.

Stop Sync Gateway

Run this command to stop the Sync Gateway container and completely remove it, using the same container id you used earlier:

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gce:~$ sudo docker stop 8ffb83fd1f && sudo docker rm 8ffb83fd1f

Update config

Copy this example JSON configuration, which expects a Couchbase Server running on http://172.17.0.2:8091, and update it with the ip address of the docker instance where your Couchbase Server is running. To get this ip address, follow the these instructions in the “Find the Docker instance IP address” section.

Now upload your modified JSON configuration to a website that is publicly accessible, for example in a Github Gist.

Run Sync Gateway

Run Sync Gateway again, this time using Couchbase Server as a backing store this time.

Replace http://yourserver.co/yourconfig.json with the URL where you’ve uploaded your JSON configuration from the previous step.

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gce:~$ sudo docker run -d -name sg -p 4984:4984 -p 4985:4985 tleyden5iwx/couchbase-sync-gateway sync_gateway "http://yourserver.co/yourconfig.json"

This will return a container id, eg 9ffb83fd1f. Again, check the logs to make sure there are no serious errors in the logs:

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gce:~$ sudo docker logs 9ffb83fd1f

You should see something along the lines of:

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... 
02:23:58.913260 Starting server on :4984 ...

with no errors.

Verify it’s working

Save a document via curl

The easiest way to add a document is via the Admin port, since there is no authentication to worry about. Since we haven’t added a firewall rule to expose the admin port (4985), (and doing so without tight filtering would be a major security hole), the following command to create a new document must be run on the GCE instance.

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gce:~$ curl -H "Content-Type: application/json" -d '{"such":"json"}' http://localhost:4985/sync_gateway/

If it worked, you should see a response like:

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{"id":"3cbfbe43e76b7eb5c4c221a78b2cf0cc","ok":true,"rev":"1-cd809becc169215072fd567eebd8b8de"}

View document on Couchbase Server

To verify the document was successfully stored on Couchbase Server, you’ll need to login to the Couchbase Server Web Admin UI. There are instructions here on how to do that.

From there, navigate to Data Buckets / default / Documents, and you should see:

Click on the document that has a UUID (eg, “29f8d7..” in the screenshot above), and you should see the document’s contents:

The _sync metadata field is used internally by the Sync Gateway and can be ignored. The actual doc contents are towards the end of the file: .."such":"json"}