How to fix Error response from daemon: config not found: myconfig in Docker

DockerBEGINNERMEDIUM

This error occurs when a Docker Swarm service references a config that doesn't exist in the swarm. Configs must be created before deploying services that use them. The fix involves creating the missing config or updating your service definition.

What this error means

The "config not found" error occurs when Docker Swarm tries to deploy or update a service that references a config object that hasn't been created in the swarm. Docker configs are a swarm-mode feature that allows you to store non-sensitive configuration data (like config files) outside of service images. Unlike secrets (which are encrypted at rest), configs are stored unencrypted and mounted directly into containers. They're useful for storing configuration files, environment-specific settings, or any data up to 500KB that your services need. This error commonly happens when: - You deploy a stack or service that references a config before creating it - The config was deleted but services still reference it - There's a typo in the config name in your docker-compose.yml or service definition - You're trying to use configs outside of swarm mode (configs only work with swarm services) - The stack file references an external config that was never created Docker configs are only available to swarm services, not standalone containers. If you're not running in swarm mode, you'll need to initialize a swarm first or use a different approach like bind mounts or environment variables.

How to fix "Error response from daemon: config not found: myconfig"

1Verify the config exists

First, check if the config actually exists in the swarm:

bash

docker config ls

Look for your config name in the output. You can also filter by name:

bash

docker config ls --filter name=myconfig

If the config isn't listed, you need to create it before deploying your service.

2Create the missing config

Create the config from a file:

bash

docker config create myconfig ./config-file.conf

Or create from stdin:

bash

echo "config content here" | docker config create myconfig -

You can also create configs from existing files with specific content:

bash

# From a JSON config file
docker config create app_config ./app-config.json

# From an nginx config
docker config create nginx_conf ./nginx.conf

After creating the config, verify it exists:

bash

docker config ls
docker config inspect myconfig

3Ensure swarm mode is active

Docker configs only work in swarm mode. Check if your node is part of a swarm:

bash

docker info | grep Swarm

If it shows "Swarm: inactive", initialize a swarm:

bash

docker swarm init

On a multi-node setup, join worker nodes:

bash

# Get the join token on a manager
docker swarm join-token worker

# Run the provided command on worker nodes
docker swarm join --token <token> <manager-ip>:2377

4Fix external config references in docker-compose

When using docker-compose.yml (v3.3+) with stack deploy, configs can be defined as external or created by the stack.

Option 1: Create config first, then reference as external:

yaml

# docker-compose.yml
version: "3.8"
services:
  app:
    image: myapp
    configs:
      - myconfig

configs:
  myconfig:
    external: true

Create the config before deploying:

bash

docker config create myconfig ./config.json
docker stack deploy -c docker-compose.yml mystack

Option 2: Let the stack create the config from a file:

yaml

version: "3.8"
services:
  app:
    image: myapp
    configs:
      - source: myconfig
        target: /app/config.json

configs:
  myconfig:
    file: ./config.json

5Update or recreate the config

Docker configs are immutable - you cannot update them in place. To change a config's content, you must remove and recreate it:

bash

# First, update services to remove the config reference
docker service update --config-rm myconfig myservice

# Remove the old config
docker config rm myconfig

# Create the new config
docker config create myconfig ./new-config.conf

# Re-add the config to the service
docker service update --config-add myconfig myservice

For stack deployments, use a versioned naming convention:

yaml

configs:
  myconfig_v2:
    file: ./config.json

services:
  app:
    configs:
      - source: myconfig_v2
        target: /app/config.json

6Debug config access in services

If the config exists but services still fail, inspect the service to verify config attachment:

bash

docker service inspect myservice --pretty

Check the "Configs" section in the output. Verify:
- The config name matches exactly (case-sensitive)
- The target path is correct
- The config UID/GID and mode are appropriate

View service task errors:

bash

docker service ps myservice --no-trunc

Check container logs for config-related issues:

bash

docker service logs myservice

How to fix Error response from daemon: config not found: myconfig in Docker

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How to fix "Error response from daemon: config not found: myconfig"

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