reshard

Distribute Redis keys across multiple instances.

Use case

Configuration

See lib/spec.js https://github.com/evanx/reshard/blob/master/lib/spec.js

module.exports = pkg => ({
    description: pkg.description,
    env: {
        redisHost: {
            description: 'the Redis host',
            default: 'localhost'
        },
        redisPort: {
            description: 'the Redis port',
            default: 6379
        },
        redisNamespace: {
            description: 'the Redis namespace',
            default: 'reshard'
        },
        popDelay: {
            description: 'pop delay',
            unit: 'ms',
            default: 2000
        },
        popTimeout: {
            description: 'pop timeout',
            unit: 'ms',
            default: 2000
        }
    },
    redisK: config => ({
        reqS: {
            key: `${config.redisNamespace}:req:s`
        },
        reqQ: {
            key: `${config.redisNamespace}:req:q`
        },
        reqH: {
            key: sha => `${config.redisNamespace}:${sha}:req:h`
        },
        busyQ: {
            key: `${config.redisNamespace}:busy:q`
        },
        reqC: {
            key: `${config.redisNamespace}:req:count:h`
        },
        errorC: {
            key: `${config.redisNamespace}:error:count:h`
        }
    })
});

Docker

See Dockerfile https://github.com/evanx/reshard/blob/master/Dockerfile

FROM mhart/alpine
ADD package.json .
RUN npm install --silent
ADD lib lib
ENV NODE_ENV production
CMD ["node", "lib/index.js"]

We can build as follows:

docker build -t reshard https://github.com/evanx/reshard.git

where tagged as image reshard

Then for example, we can run on the host's Redis as follows:

docker run --network=host -e NODE_ENV=test reshard

where --network-host connects the container to your localhost bridge. The default Redis host localhost works in that case.

Since the containerized app has access to the host's Redis instance, you should inspect the source.

Implementation

See lib/main.js https://github.com/evanx/reshard/blob/master/lib/main.js

    const sha = await client.brpoplpushAsync(redisK.reqQ, redisK.busyQ, config.popTimeout);

Uses application archetype: https://github.com/evanx/redis-koa-app

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