Error connecting Etherpad-lite to Redis database

[sbutler-gh]

When attempting to configure a Redis database with the following format (from this documentation):

  "dbType": "${DB_TYPE:redis}",
  "dbSettings": {
    "host":     "${DB_HOST:url}",
    "port":     "${DB_PORT:port}",
    "database": "${DB_NAME:0}",
    "password": "${DB_PASS:password}"
  },
  

I repeatedly got this error:

/opt/etherpad-lite/src/node_modules/async/dist/async.js:318

if (fn === null) throw new Error("Callback was already called.");

^

Error: Callback was already called.

at /opt/etherpad-lite/src/node_modules/async/dist/async.js:318:36

at Object.callbackOrEmit [as callback_or_emit] (/opt/etherpad-lite/src/node_modules/redis/lib/utils.js:89:9)

at Command.callback (/opt/etherpad-lite/src/node_modules/redis/lib/individualCommands.js:199:15)

at normal_reply (/opt/etherpad-lite/src/node_modules/redis/index.js:654:21)

at RedisClient.return_reply (/opt/etherpad-lite/src/node_modules/redis/index.js:752:9)

at JavascriptRedisParser.returnReply (/opt/etherpad-lite/src/node_modules/redis/index.js:137:18)

at JavascriptRedisParser.execute (/opt/etherpad-lite/src/node_modules/redis-parser/lib/parser.js:544:14)

at Socket.<anonymous> (/opt/etherpad-lite/src/node_modules/redis/index.js:218:27)

at Socket.emit (events.js:198:13)

at Socket.EventEmitter.emit (domain.js:448:20)

I encountered this error after with both Docker and non-Docker installations (settings.json.template and settings.json.docker)

While troubleshooting, I came across the discussion of setting values of HOST / PORT in this thread, which set me on the right path.

In the end, I updated the DBsettings in the settings.json.docker file according to the format in line 29 of this file: https://github.com/NodeRedis/node-redis/blob/master/lib/createClient.js

So the DB section of my settings.json.docker now looks like this:

  "dbType": "${DB_TYPE:redis}",
  "dbSettings": {
    "port":     "${DB_PORT:redis://:PASSWORD@HOST:PORT}"
  }

^ And that format has ended up working for me, when I run Etherpad in a docker container.

I'm not quite sure what the issue was with the original formatting, although this might be helpful to include in the documentation for Redis configurations

[JohnMcLear]

Looks like the docs just need an update for correct redis config? Can you do that please @sbutler-gh ?

[sbutler-gh]

@JohnMcLear when I posted this issue, I added an update to this documentation page.

Is that what you had in mind? Anything else?

[JohnMcLear]

Reading the code, it looks like the fix is required here:

https://github.com/ether/ueberDB/blob/master/databases/redis_db.js#L43

Testing in ether/ueberDB#182

[JohnMcLear]

Give that a test @sbutler-gh - you will need to clone the ueberdb directly into etherpad/node_modules and do an npm install etc. -- I wouldn't test it on your production site tho, defo test on a throwaway instance 📦

[sbutler-gh]

@JohnMcLear I went through the links, looks like a fix got identified and committed? I could test locally with ueberdb if it's important (for you/the project), but I'd need more of a step-by-step instruction for how to do that. To be clear, I'm not really concerned with my own instance in this case because I got these working already, so just let me know what would be preferable

[JohnMcLear]

I think we're good to close this w/ the @rhansen fixes and the change to settings handle things should be better for Redis users now :)