This is the third part of a series about deploying a non-Rails application with Kamal 2. Read the previous article here. Follow this journey at https://github.com/jjeffers/sherldoc.
Deploying a Queue Worker
I need to provision a “version” of sherldoc that will handle workers to process asynchronous jobs for the web application. The original sherldoc docker compose layout used a shared docker volume and the same sherldoc web container to run the queue workers.
In our configuration the containers don’t share a mounted volume at runtime. Instead, each image uses the same container image with similar post-run commands. The final docker entrypoint commands will diverge, with the queue worker starting the artisan worker process instead of the web application server steps.
Our deploy.yml includes the following additional server entry:
...
image: sherldoc-web
...
servers:
web:
hosts:
- 159.203.76.193
cmd: bash -c "/app/prepare_app.sh && cd /app/public; frankenphp php-server"
workers:
hosts:
- 159.203.76.193
...
Kamal uses every server entry to deploy a container of the image entry, “sherldoc-web”. I can override the “workers” container with a new CMD.
After a another deploy I check kamal app details :
kamal app details -c ./deploy.yml
INFO [006857a0] Running docker ps --filter label=service=sherldoc --filter label=role=web on 159.203.76.193
INFO [006857a0] Finished in 2.108 seconds with exit status 0 (successful).
App Host: 159.203.76.193
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
bc7b3029bda6 registry.digitalocean.com/team-james-demo/sherldoc-web:[...] "docker-php-entrypoi…" About a minute ago Up About a minute 80/tcp, 9000/tcp sherldoc-web-[...]
INFO [4c339292] Running docker ps --filter label=service=sherldoc --filter label=role=workers on 159.203.76.193
INFO [4c339292] Finished in 0.229 seconds with exit status 0 (successful).
App Host: 159.203.76.193
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
a913b7fcd417 registry.digitalocean.com/team-james-demo/sherldoc-web:[...] "docker-php-entrypoi…" About a minute ago Up About a minute 80/tcp, 9000/tcp sherldoc-workers-[...]
Both containers are up, but the container with the name “sherldoc-workers” started with the artisan queue:work command.
Why No Supervisor?
I debated adding the supervisor (the process control utility) indicated in the source project’s docker compose configuration.
I suspect if sherldoc-workers container halted kamal-proxy would then restart it. I am not aware of any restart policy set for the docker containers on the server. Any restart would have to be external to the docker engine.
I tested this theory, attaching to the sherldoc-worker container and killing the main process, artisan queue:work. Within a few moments a new sherldoc-workers container was up and running.
Given this, I decide not to install or run supervisor.
Booting Additional Accessories
Next, I stand up Redis and Apache Tika.
...
accessories:
...
redis:
host: 159.203.76.193
image: redis:6
directories:
- data.redis:/data
tika:
image: apache/tika:2.9.2.1-full
ports:
- 9998:9998
With that configuration change I start the redis instance:
kamal accessory boot redis -c ./deploy.yml
INFO [2f687e13] Running /usr/bin/env mkdir -p .kamal on 159.203.76.193
INFO [2f687e13] Finished in 1.466 seconds with exit status 0 (successful).
Acquiring the deploy lock...
INFO [bdb656a9] Running docker login registry.digitalocean.com/team-james-demo -u [REDACTED] -p [REDACTED] on 159.203.76.193
INFO [bdb656a9] Finished in 0.936 seconds with exit status 0 (successful).
INFO [34829155] Running docker network create kamal on 159.203.76.193
INFO [16f49764] Running /usr/bin/env mkdir -p $PWD/sherldoc-redis/data.redis on 159.203.76.193
INFO [16f49764] Finished in 0.210 seconds with exit status 0 (successful).
INFO [bf65cb9c] Running /usr/bin/env mkdir -p .kamal/apps/sherldoc/env/accessories on 159.203.76.193
INFO [bf65cb9c] Finished in 0.171 seconds with exit status 0 (successful).
INFO Uploading .kamal/apps/sherldoc/env/accessories/redis.env 100.0%
INFO [f431adff] Running docker run --name sherldoc-redis --detach --restart unless-stopped --network kamal --log-opt max-size="10m" --env-file .kamal/apps/sherldoc/env/accessories/redis.env --volume $PWD/sherldoc-redis/data.redis:/data --label service="sherldoc-redis" redis:6 on 159.203.76.193
INFO [f431adff] Finished in 1.865 seconds with exit status 0 (successful).
Releasing the deploy lock...
And finally, I spin up the Tika instance:
kamal accessory boot tika -c ./deploy.yml
INFO [32435277] Running /usr/bin/env mkdir -p .kamal on 159.203.76.193
INFO [32435277] Finished in 1.398 seconds with exit status 0 (successful).
Acquiring the deploy lock...
INFO [42be2d9b] Running docker login registry.digitalocean.com/team-james-demo -u [REDACTED] -p [REDACTED] on 159.203.76.193
INFO [42be2d9b] Finished in 0.537 seconds with exit status 0 (successful).
INFO [e9abb23f] Running docker network create kamal on 159.203.76.193
INFO [b36fa775] Running /usr/bin/env mkdir -p .kamal/apps/sherldoc/env/accessories on 159.203.76.193
INFO [b36fa775] Finished in 0.207 seconds with exit status 0 (successful).
INFO Uploading .kamal/apps/sherldoc/env/accessories/tika.env 100.0%
INFO [94a1e92e] Running docker run --name sherldoc-tika --detach --restart unless-stopped --network kamal --log-opt max-size="10m" --publish 9998:9998 --env-file .kamal/apps/sherldoc/env/accessories/tika.env --label service="sherldoc-tika" apache/tika:2.9.2.1-full on 159.203.76.193
INFO [94a1e92e] Finished in 16.586 seconds with exit status 0 (successful).
Releasing the deploy lock...
So far everything looks like it’s working, or at least the parts are operational. I’ll dive into the application itself next and see is working under the hood.
Plan Zero 
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