Demo Using Envconsul to monitor Changes to Consul KV

In this tutorial, you’ll learn how to install and run HashiCorp envconsul on an application server. Envconsul fetches key-value pairs from Consul and exposes them as environment variables, automatically watching for changes without manual intervention.

Prerequisites

A running Consul cluster with KV entries under apps/ecommerce
SSH access to your application server
(Optional) Consul ACL token if your cluster enforces ACLs

Example KV Entries

Consul KV Path	Value
`apps/ecommerce/database_host`	`"customer-db"`
`apps/ecommerce/database`	`"billing"`
`apps/ecommerce/connection_string`	`"Server=customer-db;Database=billing;User Id=..."`

1. Install envconsul

Download the latest Linux AMD64 binary from HashiCorp’s release archive:

curl --silent -Lo /tmp/envconsul.zip \
  https://releases.hashicorp.com/envconsul/0.11.0/envconsul_0.11.0_linux_amd64.zip

Unzip and move the binary into your PATH:

unzip /tmp/envconsul.zip -d /tmp
sudo mv /tmp/envconsul /usr/local/bin/

Verify the installation:

envconsul --version
# => envconsul v0.11.0

Note

Make sure to update the version number in the URL if a newer release is available.

2. Fetch and Export KV Data

Use envconsul to pull all keys under the apps/ecommerce prefix and convert them to uppercase environment variables:

envconsul \
  -prefix="apps/ecommerce" \
  -uppercase \
  -- printenv

Sample output:

DATABASE_HOST=customer-db
DATABASE=billing
CONNECTION_STRING=Server=customer-db;Database=billing;User Id=...

Common Flags

Flag	Description
`-prefix`	Consul KV path to fetch
`-uppercase`	Convert all keys to uppercase environment variable
`--`	Separator before the command to execute

3. Launch Your Application with envconsul

To ensure your application picks up the variables at startup and on any KV change:

envconsul \
  -prefix="apps/ecommerce" \
  -uppercase \
  -- ./start-your-app.sh

Warning

If your app requires a Consul ACL token, set CONSUL_HTTP_TOKEN in the environment or pass -token to envconsul.

Summary

In this demo, you:

Installed envconsul on a Linux server.
Retrieved KV pairs from Consul and exposed them as environment variables.
Launched your application to inherit and watch for configuration updates automatically.

By integrating envconsul, your service maintains up-to-date settings without manual polling or restarts.

Links and References

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