relist v0.1.1
relist
Import from set to queue.
Use case
We wish to send alerts for application errors to a Slack channel.
Our application services use a logger which writes errors into Redis.
Consider the following common error logging method.
logger.error(err);
The implementation logs the latest error into Redis, according to the client ID.
multi.hmset(`reconsole:error:${clientId}:h`, {
time: new Date(timestamp).toISOString(),
message: err.message
});
multi.sadd('reconsole:error:s', clientId);
e.g. see Uses application archetype: https://github.com/evanx/reconsole
This service will POST
alerts to a Slack channel, e.g. in collaboration with reconsole.
Configuration
See lib/spec.js
https://github.com/evanx/relist/blob/master/lib/spec.js
module.exports = pkg => ({
description: pkg.description,
env: {
redisHost: {
description: 'the Redis host',
default: 'localhost'
},
redisPort: {
description: 'the Redis port',
default: 6379
},
redisNamespace: {
description: 'the Redis namespace',
default: 'relist'
},
slackUrl: {
description: 'Slack URL',
},
slackChannel: {
description: 'Slack channel',
default: '#ops'
},
slackUsername: {
description: 'Slack username',
default: 'relistBot'
},
slackIcon: {
description: 'Slack icon emoji',
default: 'monkey'
},
popDelay: {
description: 'pop delay',
unit: 'ms',
default: 2000
},
popTimeout: {
description: 'pop timeout',
unit: 'ms',
default: 2000
}
},
redisK: config => ({
reqS: {
key: `${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/relist/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 relist https://github.com/evanx/relist.git
where tagged as image relist
Then for example, we can run on the host's Redis as follows:
docker run --network=host -e slackUrl=$SLACK_URL relist
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/relist/blob/master/lib/main.js
const sha = await client.brpoplpushAsync(redisK.reqQ, redisK.busyQ, config.popTimeout);
const [hashes] = await multiExecAsync(client, multi => {
multi.hgetall(redisK.reqH(sha));
multi.hincrby(redisK.reqC, 'pop', 1);
});
asserto({hashes});
const {text} = hashes;
asserto({text});
const payload = {
channel: config.slackChannel,
username: config.slackUsername,
icon_emoji: [':', config.slackIcon, ':'].join(''),
text
};
const fetchRes = await fetch(req.url, {
url: config.slackUrl,
method: 'POST',
headers: {
'content-type': 'application/x-www-form-urlencoded'
},
body: 'payload=' + JSON.stringify(payload).replace(/"/g, '\'')
});
if (fetchRes.status !== 200) {
throw new DataError(`Status ${fetchRes.status}`, payload);
}
Uses application archetype: https://github.com/evanx/redis-koa-app
7 years ago