How to fix Error response from daemon: secret not found: mysecret in Docker

First, check what secrets currently exist in your Swarm cluster:

docker secret ls

This command must be run on a Swarm manager node. If you see your secret listed, the issue is likely a name mismatch. If it's not listed, you need to create it.

You can also inspect a specific secret to see its metadata (not the value):

docker secret inspect mysecret

Secret management commands only work on manager nodes. Check your node's role:

docker info | grep "Is Manager"

If you see "Is Manager: false" or get an error about Swarm not being active, you need to either:

1. SSH into a manager node, or
2. Initialize Swarm if it's not running:

docker swarm init

Create the secret using one of these methods:

From a file:

docker secret create mysecret /path/to/secret/file

From stdin (recommended for sensitive data):

echo "my_secret_value" | docker secret create mysecret -

Or using printf to avoid newline issues:

printf "my_secret_value" | docker secret create mysecret -

After creation, verify it exists:

docker secret ls

Check your docker-compose.yml or service definition to ensure the secret name matches exactly (case-sensitive).

In docker-compose.yml:

services:
  myapp:
    image: myapp:latest
    secrets:
      - mysecret  # Must match the secret name exactly

secrets:
  mysecret:
    external: true  # References an existing Swarm secret

For external secrets, the name must match what's in docker secret ls. If you're defining the secret in the compose file itself:

secrets:
  mysecret:
    file: ./my_secret.txt  # Creates secret from file during deploy

After creating or fixing the secret, redeploy your service:

Using docker stack:

docker stack deploy -c docker-compose.yml mystack

Using docker service:

docker service update --secret-add mysecret myservice

Or if recreating the service:

docker service create --name myservice --secret mysecret myimage

Once the service is running, verify the secret is mounted correctly:

docker exec -it <container_id> ls -la /run/secrets/
docker exec -it <container_id> cat /run/secrets/mysecret

The secret should be available as a file at /run/secrets/mysecret. Your application should read from this file path, not from an environment variable.